JP2013235683A - Negative electrode for nonaqueous electrolytic secondary battery, and nonaqueous electrolytic secondary battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a negative electrode for a nonaqueous electrolytic secondary battery with high capacity and good cycle characteristic.SOLUTION: The negative electrode for a nonaqueous electrolytic secondary battery has a current collector 3, and an active material layer 5 on the current collector 3. The active material layer 5 includes nanometer-size particles 7 containing an element A, and a binding agent 9. The element A includes at least one element selected from a group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In and Zn. The nanometer-size particles 7 are covered with the binding agent 9. The binding agent 9 includes at least one material selected from a group consisting of polyimide, polyamide imide, polybenzimidazole and polyamide.

Description

  The present invention relates to a negative electrode for a non-aqueous electrolyte secondary battery, and more particularly to a negative electrode for a non-aqueous electrolyte secondary battery having a high capacity and a long life.

  Conventionally, nonaqueous electrolyte secondary batteries (lithium ion secondary batteries) using graphite as a negative electrode active material have been put into practical use. In these nonaqueous electrolyte secondary batteries, a slurry obtained by kneading active material particles 207, a binder 209, and a conductive additive 211 such as carbon black as shown in FIG. The negative electrode 201 for a non-aqueous electrolyte secondary battery in which an active material layer 205 was formed by coating and drying was used.

  On the other hand, negative electrodes for non-aqueous electrolyte secondary batteries using metals and alloys having a large theoretical capacity as lithium compounds, particularly silicon and alloys thereof as negative electrode active materials, have been developed with the aim of increasing the capacity. However, since the volume of silicon that occludes lithium ions expands to about 4 times that of silicon before occlusion, a negative electrode using a silicon-based alloy as a negative electrode active material repeatedly expands and contracts during a charge / discharge cycle. For example, FIG. 23 shows the active material particles 207a after charging in which the silicon-based active material particles 207 are expanded about 4 times in volume and about 60% in linear expansion coefficient after charging. For this reason, the negative electrode active material is pulverized, the negative electrode active material is peeled off from the current collector, and the life is extremely short compared to the conventional graphite electrode.

  Moreover, when apply | coating the slurry containing these negative electrode active materials, using rubber-type binders, such as a styrene butadiene rubber, was performed (refer patent document 1).

JP 2010-103065 A

  However, a conventional negative electrode that forms a negative electrode by applying and drying a slurry of a negative electrode active material, a conductive additive, and a binder has a low conductivity for the negative electrode active material, the conductive additive, and the current collector. When the resin is bound with a resin binder, the amount of resin used must be minimized so that the internal resistance does not increase, and the bonding strength is weak. Therefore, if the volume expansion of silicon due to charge / discharge cannot be suppressed, pulverization of the negative electrode active material, peeling of the negative electrode active material layer from the current collector, generation of cracks in the negative electrode, decrease in conductivity between the negative electrode active materials Etc. occur and the capacity decreases. Therefore, there are problems that the cycle characteristics are poor and the life of the secondary battery is short.

  In particular, as in Patent Document 1, when a rubber-based binder is used, the rubber-based binder is added to the slurry as an emulsion in which particulate rubber is dispersed in water. Further, in the obtained active material layer 205, the granular binder 209 fixes the active material particles 207 to each other or the active material particles 207 and the current collector 203 by point contact. For this reason, when the active material particles expand and contract, it is difficult to prevent the active material particles from peeling from the current collector.

  In particular, silicon, which is expected to be put to practical use as a negative electrode material, has a problem that cracking easily occurs and charge / discharge cycle characteristics are poor because the volume change during charge / discharge is large.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to obtain a negative electrode for a non-aqueous electrolyte secondary battery having high capacity and good cycle characteristics.

  As a result of intensive studies to achieve the above object, the present inventor has joined the first phase, which is liable to occlude lithium, to another phase, which is difficult to occlude lithium, via the interface. Since the other phase is difficult to expand when lithium absorbs lithium and expands, the expansion of the first phase in contact with the other phase is suppressed, and the nano-sized particles are prevented from being finely charged / discharged. Furthermore, it has been found that the use of a specific type of binder having a high strength that covers the surface of the nano-sized particles improves the cycle characteristics. The present invention has been made based on this finding.

That is, the present invention provides the following negative electrode for a nonaqueous electrolyte secondary battery.
(1) A negative electrode for a non-aqueous electrolyte secondary battery having an active material layer on a current collector, wherein the active material layer includes nano-sized particles containing element A and element D, and a binder. The element A is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In and Zn, and the element D is Fe, Co, Ni, Ca, Sc Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), Hf, Ta, W, Re, Os, Ir At least one selected element, and the nano-sized particles include at least a first phase that is a simple substance or a solid solution of the element A and a second phase that is a compound of the element A and the element D. The first phase and the second phase are bonded via an interface. The first phase and the second phase are exposed on the outer surface of the nanosized particles, and the first phase has a substantially spherical surface except for the interface, and the nanosize At least a part of the surface of the particles is covered with the binder, and the binder is one or more selected from the group consisting of polyimide, polyamideimide, polybenzimidazole, and polyamide. A negative electrode for a non-aqueous electrolyte secondary battery.
(2) The element A is Si, and the element D is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Ba The negative electrode for a nonaqueous electrolyte secondary battery according to (1), which is at least one element selected from the group consisting of Hf, Ta, W, and Ir.
(3) The negative electrode for a nonaqueous electrolyte secondary battery according to (1) or (2), wherein the second phase of the nano-sized particles is a compound of DA _x (1 <x ≦ 3) .
(4) Furthermore, the nano-sized particles have a third phase that is a compound of the element A and the element D, and the third phase is dispersed in the first phase. The negative electrode for a nonaqueous electrolyte secondary battery according to any one of (1) to (3).
(5) Any of (1) to (4), wherein the first phase is mainly crystalline silicon, and the second phase and / or the third phase is crystalline silicide. A negative electrode for a non-aqueous electrolyte secondary battery according to 1.
(6) The nano-sized particles are Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (Pm The element D ′ which is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir, and the element D ′ constitutes the second phase. The element D is a different type of element, and the nano-sized particles further include a fourth phase that is a compound of the element A and the element D ′, and the first phase and the fourth phase. Are bonded via an interface, and the fourth phase is exposed on the outer surface of the nano-sized particles, according to any one of (1) to (5), Negative electrode for electrolyte secondary battery.
(7) A negative electrode for a nonaqueous electrolyte secondary battery having an active material layer on a current collector, wherein the active material layer includes nano-sized particles containing element A and element M, and a binder. The element A is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, and the element M is selected from the group consisting of Cu, Ag, and Au. The at least one selected element, and the nano-sized particles include a sixth phase which is a simple substance or a solid solution of the element A, a compound of the element A and the element M, or a simple substance or a solid solution of the element M. And the sixth phase and the seventh phase are bonded via an interface, and both the sixth phase and the seventh phase are the nanophases. The outer surface of the size particle is exposed, and the sixth phase and the seventh phase are interfaces. The outside has a substantially spherical surface, and at least a part of the surface of the nano-sized particles is covered with the binder, and the binder is made of polyimide, polyamideimide, polybenzimidazole, or polyamide. A negative electrode for a non-aqueous electrolyte secondary battery, wherein the negative electrode is one or more selected from the group.
(8) The negative electrode for a nonaqueous electrolyte secondary battery according to (7), wherein the seventh phase is a compound of MA _x (x ≦ 1, 3 <x).
(9) The nano-sized particles further include at least one element M ′ selected from the group consisting of Cu, Ag, and Au, and the element M ′ includes the element M constituting the seventh phase Are different kinds of elements, and the nano-sized particles further include an eighth phase that is a compound of the element A and the element M ′, or a simple substance or a solid solution of the element M ′, and the sixth phase. And the eighth phase are bonded via an interface, the eighth phase is exposed on the outer surface of the nanosize particle, and the eighth phase is spherical except for the interface. The negative electrode for a non-aqueous electrolyte secondary battery according to (7) or (8), wherein
(10) The nano-sized particles are Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (Pm Except), and further includes an element D that is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir, and the nano-sized particles include a compound of the element A and the element D. And the sixth phase and the ninth phase are bonded via an interface, and the ninth phase is exposed on the outer surface of the nano-sized particles. The negative electrode for a nonaqueous electrolyte secondary battery according to any one of (7) to (9), wherein
(11) The nano-sized particles further include a tenth phase that is a compound of the element A and the element D, and a part or all of the tenth phase is covered with the sixth phase. The negative electrode for a non-aqueous electrolyte secondary battery according to any one of (7) to (10).
(12) The nano-sized particles include Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (Pm The element D ′, which is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir, and the element D ′ constitutes the ninth phase. The element D is an element of a different type, and the nano-sized particles further have an eleventh phase that is a compound of the element A and the element D ′, and the sixth phase and the eleventh phase. Are bonded via an interface, and the eleventh phase is exposed on the outer surface of the nano-sized particles. The negative electrode for a non-aqueous electrolyte secondary battery according to (10),
(13) The nano-sized particles further include a twelfth phase that is a compound of the element A and the element D ′, and a part or all of the twelfth phase covers the sixth phase. The negative electrode for a nonaqueous electrolyte secondary battery according to (12), wherein
(14) A negative electrode for a non-aqueous electrolyte secondary battery having an active material layer on a current collector, wherein the active material layer includes nano-sized particles containing an element A-1, an element A-2, and an element D; And the element A-1 and the element A-2 are two kinds of elements selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, Element D is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, a lanthanoid element (except Pm), Hf, The nano-sized particles are at least one element selected from the group consisting of Ta, W, Re, Os, and Ir, and the nano-sized particles include a thirteenth phase that is a single element or a solid solution of the element A-1, and the element A. -14, which is a simple substance or a solid solution of -2, and a combination of the element A-1 and the element D And the thirteenth phase and the fourteenth phase are joined via an interface, and the thirteenth phase and the fifteenth phase The thirteenth phase and the fourteenth phase have substantially spherical surfaces except for the interface, and the thirteenth phase, the fourteenth phase, and the fifteenth phase. Are exposed on the outer surface of the nano-sized particles, and at least a part of the surface of the nano-sized particles is covered with the binder, and the binder is polyimide, polyamideimide, polybenzimidazole, A negative electrode for a non-aqueous electrolyte secondary battery, wherein the negative electrode is one or more selected from the group consisting of polyamides.
(15) The element A-1 and the element A-2 are two kinds of elements selected from the group consisting of Si, Sn, and Al, and the element D is Fe, Co, Ni, Ca, Sc, The non-element according to (14), which is one element selected from the group consisting of Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, and Ba. Negative electrode for water electrolyte secondary battery.
(16) The nano-sized particles further include a sixteenth phase that is a compound of the element A-1 and the element D, and a part or all of the sixteenth phase is converted into the thirteenth phase. The negative electrode for a nonaqueous electrolyte secondary battery according to (14) or (15), wherein the negative electrode is covered.
(17) The nanosized particle further includes a seventeenth phase that is a compound of the element A-1 and the element D, and the seventeenth phase is bonded to the fourteenth phase through an interface. The negative electrode for a nonaqueous electrolyte secondary battery according to any one of (14) to (16), wherein the negative electrode is exposed on the outer surface of the battery.
(18) One or more of the fifteenth phase, the sixteenth phase, and the seventeenth phase is a compound represented by D (A-1) _y (1 <y ≦ 3) The negative electrode for a nonaqueous electrolyte secondary battery according to any one of (14) to (17).
(19) The nano-sized particles further include an element A-3 that is one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, and the element A -3 is an element different from the element A-1 and the element A-2, and the nano-sized particles have an eighteenth phase that is a simple substance or a solid solution of the element A-3, The thirteenth phase and the eighteenth phase are joined via an interface, the eighteenth phase has a substantially spherical surface other than the interface, and the eighteenth phase is the nanophase. The negative electrode for a nonaqueous electrolyte secondary battery according to (14), which is exposed on the outer surface of the size particles.
(20) The nano-sized particles include Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (Pm The element D ′, which is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir, and the element D ′ constitutes the fifteenth phase. The element D is a different type of element, and the nano-sized particles further include a nineteenth phase that is a compound of the element A-1 and the element D ′, and the thirteenth phase and the nineteenth phase. The negative electrode for a non-aqueous electrolyte secondary battery according to (14), wherein the phase is bonded via an interface, and the nineteenth phase is exposed on the outer surface of the nano-sized particles .
(21) The nano-sized particles further include a twentieth phase that is a compound of the element A-1 and the element D ′, and a part or all of the twentieth phase is the thirteenth phase. The negative electrode for a nonaqueous electrolyte secondary battery according to (20), which is covered with
(22) The negative electrode for a nonaqueous electrolyte secondary battery according to any one of (1) to (21), wherein the nano-sized particles have an average particle diameter of 2 to 500 nm.
(23) The active material layer further includes any one or more of carbon black, carbon nanotubes, and carbon fibers as a conductive additive, according to any one of (1) to (22), Negative electrode for non-aqueous electrolyte secondary battery.
(24) a positive electrode capable of inserting and extracting lithium ions; a negative electrode according to any one of (1) to (23); and a separator disposed between the positive electrode and the negative electrode; A non-aqueous electrolyte secondary battery, wherein the positive electrode, the negative electrode, and the separator are provided in a conductive electrolyte.

  According to the present invention, a negative electrode for a non-aqueous electrolyte secondary battery having a high capacity and good cycle characteristics can be obtained.

(A), (b) The schematic sectional drawing of the negative electrode 1 for nonaqueous electrolyte secondary batteries which concerns on this invention, 1a. (A), (b), (c) Schematic sectional drawing which shows the nanosized particle which concerns on 1st Embodiment. (A), (b) The schematic sectional drawing which shows the other example of the nanosized particle which concerns on 1st Embodiment. (A), (b) The schematic sectional drawing which shows the other example of the nanosized particle which concerns on 1st Embodiment. The figure which shows the nanosize particle manufacturing apparatus which concerns on this invention. (A), (b) The schematic sectional drawing of the nanosized particle which concerns on 2nd Embodiment. (A), (b), (c) The schematic sectional drawing of the nanosized particle which concerns on 3rd Embodiment. (A), (b) Schematic sectional drawing of the nanosized particle which concerns on the other example of 3rd Embodiment. (A), (b) Schematic sectional drawing of the nanosized particle which concerns on the other example of 3rd Embodiment. The schematic sectional drawing of the nanosized particle which concerns on the other example of 3rd Embodiment. (A), (b), (c) The schematic sectional drawing of the nanosized particle which concerns on 4th Embodiment. (A), (b) The schematic sectional drawing of the other example of the nanosized particle which concerns on 4th Embodiment. (A), (b) The schematic sectional drawing of the other example of the nanosized particle which concerns on 4th Embodiment. (A), (b) The schematic sectional drawing of the other example of the nanosized particle which concerns on 4th Embodiment. Sectional drawing which shows the example of the nonaqueous electrolyte secondary battery which concerns on this invention. (A), (b) The schematic diagram before and after charge of the nanosized particle which concerns on this invention. The XRD analysis result of the nanosize particle which concerns on Example 1. FIG. 4 is a TEM photograph of nanosized particles according to Example 1. FIG. (A) HAADF-STEM photograph of nano-sized particles according to Example 1, (b) to (c) EDS map in the same field of view. Comparison of cycle characteristics of Example 1, Comparative Example 1, and Comparative Example 2. (A) SEM photograph of the negative electrode according to Example 1, and (b) SEM photograph of the negative electrode according to Comparative Example 1. The schematic sectional drawing which shows the conventional negative electrode for nonaqueous electrolyte secondary batteries. (A), (b) The schematic diagram before and after charge of the conventional active material particle.

(1. Negative electrode for non-aqueous electrolyte secondary battery)
(1-1. Configuration of negative electrode for nonaqueous electrolyte secondary battery)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Fig.1 (a) is a schematic sectional drawing which shows the negative electrode 1 for nonaqueous electrolyte secondary batteries which concerns on this invention.
The negative electrode 1 for a nonaqueous electrolyte secondary battery has an active material layer 5 on a current collector 3. The active material layer 5 includes nano-sized particles 7 and a binder 9. The surfaces of the nano-sized particles 7 and the conductive additive 10 are partially or entirely covered with the binder 9 and are dispersed in the resin matrix of the binder 9. The nano-sized particles 7 and the conductive additive 10 are bonded in a state where most of the nano-sized particles 7 and the conductive additive 10 are filled with the binder 9, thereby obtaining an effect of preventing the nano-sized particles 7 from being separated from the current collector 3.

  The binder 9 is at least one selected from the group consisting of polyimide, polyamideimide, polybenzimidazole, and polyamide.

  The binder 9 is added to the slurry in a state dissolved in a solvent. The binder 9 forms a coating film on the surface of the nano-sized particles 7 after slurry application, and the binder 9 covers the surface of the nano-sized particles 7. The binder 9 itself is a resin having a higher strength than conventional styrene butadiene rubber. Therefore, the nano-sized particles 7 are firmly bound by the binder 9 and further firmly adhered to the current collector 3.

  The negative electrode 1 for a non-aqueous electrolyte secondary battery according to the present invention uses a high-strength polyimide or the like as a binder 9 for fixing the nano-sized particles 7 as the active material layer 5 on the current collector 3. The nano-sized particles 7 are firmly bound to each other, and the current collector 3 and the nano-sized particles 7 are firmly adhered. Further, since the binder 9 such as polyimide covers the surface of the nano-sized particles 7, the nano-sized particles can be prevented from being pulverized. Therefore, the negative electrode 1 for a nonaqueous electrolyte secondary battery according to the present invention has a long life.

  As shown in FIG. 22, styrene butadiene rubber (SBR) used as a conventional binder and dispersed in water as an emulsion is slurried together with carboxymethyl cellulose (CMC) as a thickener. To be mixed. In FIG. 22, the SBR binder 209 has the particulate binder 209 bonding the active material particles 207 in a point contact manner within the active material layer 205. Therefore, the effect of suppressing the dropping of the active material particles 207 containing silicon is small.

  Carboxymethylcellulose (CMC) is used as a thickener for slurry, but has low adhesion to a current collector such as copper foil, and even if CMC is contained in the slurry, the active material particles containing silicon The active material particles are peeled off from the current collector during expansion and contraction, resulting in poor cycle characteristics.

  As another conventional binder, polyvinylidene fluoride (PVdF) dissolved in an organic solvent is used. Since the conventional graphite-based negative electrode active material did not expand and contract so much, when PVdF was used as a binder, the dispersibility of the active material particles was improved, which was favorable. However, when active material particles containing silicon or the like are used, these active material particles expand and contract, but PVdF is used because PVdF has poor followability when the active material particles contract after expansion. The negative electrode has poor cycle characteristics.

  Moreover, in this invention, the dispersibility of the nanosized particle 7 in a slurry is good, and the nanosized particle 7 does not form an aggregate in a slurry, The surface of the active material layer 5 obtained by apply | coating a slurry Becomes smooth.

  Moreover, like the negative electrode 1a for nonaqueous electrolyte secondary batteries shown in FIG.1 (b), in addition to the nanosized particle 7 and the binder 9, you may add the conductive support agent 10 in the active material layer 5a. .

  The conductive auxiliary agent 10 is a powder made of at least one conductive material selected from the group consisting of carbon, copper, tin, zinc, nickel, silver and the like. A single powder of carbon, copper, tin, zinc, nickel, or silver may be used, or a powder of each alloy may be used. For example, general carbon black such as furnace black and acetylene black can be used.

  By adding the conductive additive 10, the conductivity of the active material layer 5a of the negative electrode 1a is improved, and charging / discharging is facilitated.

(1-3. Method for producing negative electrode for nonaqueous electrolyte secondary battery)
First, a slurry raw material is put into a mixer and kneaded to form a slurry. The slurry raw material is nano-sized particles, a conductive aid, a binder, a thickener, a solvent, and the like.

  The solid content in the slurry contains 25 to 95% by weight of nano-sized particles, 0 to 70% by weight of conductive aid, 1 to 30% by weight of binder, and 0 to 25% by weight of thickener. Preferably, the solid content is 50 to 90% by mass of nano-sized particles. It is a ratio of 5 to 30% by mass of a conductive additive and 5 to 25% by mass of a binder. When there are too few binders, adhesiveness will fall and it will be difficult to maintain the shape of a granulated body and an electrode. Moreover, when there are too many binders, electroconductivity will fall and charging / discharging will become difficult.

  As the mixer, a general kneader used for preparing a slurry can be used, and a device called a kneader, a stirrer, a disperser, a mixer, or the like that can prepare a slurry may be used. N-methyl-2-pyrrolidone can be used as the solvent.

  The conductive assistant is a powder made of at least one conductive material selected from the group consisting of carbon, copper, tin, zinc, nickel, silver and the like. A single powder of carbon, copper, tin, zinc, nickel, or silver may be used, or a powder of each alloy may be used. For example, general carbon black such as furnace black and acetylene black can be used. In particular, when the element A of the nano-sized particles is silicon having low conductivity, silicon is exposed on the surface of the nano-sized particles, and the conductivity becomes low. Therefore, carbon nanohorn may be added as a conductive auxiliary agent. preferable. Here, the carbon nanohorn (CNH) has a structure in which a graphene sheet is rounded into a conical shape, and the actual form is an aggregate of a shape like a radial sea urchin with many CNHs facing the apex to the outside. Exists as. The outer diameter of the CNH sea urchin-like aggregate is about 50 nm to 250 nm. In particular, CNH having an average particle size of about 80 nm to 150 nm is preferable.

  The average particle size of the conductive assistant refers to the average particle size of the primary particles. Even when the structure shape is highly developed such as acetylene black (AB), the average particle diameter can be defined by the primary particle diameter here, and the average particle diameter can be obtained by image analysis of the SEM photograph.

  Moreover, you may use both a particulate-form conductive support agent and a wire-shaped conductive support agent. The wire-shaped conductive aid is a wire made of a conductive material, and the conductive materials listed in the particulate conductive aid can be used. As the wire-shaped conductive assistant, a linear body having an outer diameter of 300 nm or less, such as carbon fiber, carbon nanotube, copper nanowire, or nickel nanowire, can be used. By using a wire-shaped conductive aid, electrical connection with the negative electrode active material or current collector is easily maintained, and the current collection performance is improved. Cracks are less likely to occur. For example, it is conceivable to use AB or copper powder as the particulate conductive aid, and use vapor grown carbon fiber (VGCF) as the wire shaped conductive aid. In addition, you may use only a wire-shaped conductive support agent, without adding a particulate-form conductive support agent.

  The length of the wire-shaped conductive assistant is preferably 0.1 μm to 2 mm. The outer diameter of the conductive additive is preferably 2 nm to 500 nm, more preferably 10 nm to 200 nm. If the length of the conductive auxiliary agent is 0.1 μm or more, the length is sufficient to increase the productivity of the conductive auxiliary agent, and if the length is 2 mm or less, application of the slurry is easy. Further, when the outer diameter of the conductive auxiliary agent is larger than 2 nm, the synthesis is easy, and when the outer diameter is smaller than 500 nm, the slurry is easily kneaded. The measuring method of the outer diameter and length of the conductive material was performed by image analysis using SEM.

  The binder is a resin binder, and one or more organic materials selected from the group consisting of polyimide, polyamideimide, polybenzimidazole, and polyamide can be used.

  Next, the slurry is applied to one surface of the current collector using, for example, a coater. As the coater, a general coating apparatus capable of applying the slurry to the current collector can be used. Examples of the coater include a roll coater, a doctor blade coater, a comma coater, and a die coater.

  The current collector is a foil made of at least one metal selected from the group consisting of copper, nickel, and stainless steel. Each may be used alone or may be an alloy of each. The thickness is preferably 4 μm to 35 μm, and more preferably 8 μm to 18 μm.

  The prepared slurry is uniformly applied to the current collector, then dried at about 50 to 150 ° C., and passed through a roll press to adjust the thickness. Then, one or more binders selected from the group consisting of polyimide, polyamideimide, polybenzimidazole, and polyamide are fired at 150 ° C. to 350 ° C. to obtain a negative electrode for a nonaqueous electrolyte secondary battery.

(1-4. Nano-sized particles)
As the nano-sized particles 7, nano-sized particles 11, 17, 18, 21, 22, 23, 27, 61, 67, 71, 75, 76, 79, 81, 83, 87, 91, 101, 109, which will be described later. 110, 113, 117, 119, 123, 125, 129 can be used.

(2. Nano-sized particles according to the first embodiment)
(2-1. Configuration of nano-sized particles)
The nanosize particle 11 according to the first embodiment will be described.
FIG. 2 is a schematic cross-sectional view showing the nano-sized particles 11. The nano-sized particle 11 has a first phase 13 and a second phase 15, and the first phase 13 has a substantially spherical surface other than the interface, and the second phase 15 is the first phase. It is bonded to the phase 13 via the interface. The interface between the first phase 13 and the second phase 15 is a flat surface or a curved surface. Further, the interface may be stepped.

  The first phase 13 is a single element A, and the element A is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn. The element A is an element that easily stores lithium. Note that the first phase 13 may be a solid solution containing the element A as a main component. The first phase 13 may be crystalline or amorphous. The element that forms a solid solution with the element A may be an element selected from the group in which the element A can be selected, or an element not listed in the group. The first phase 13 can occlude and desorb lithium. The first phase 13 becomes amorphous when occluded by lithium and alloyed and then desorbed and dealloyed.

  When the surface other than the interface is substantially spherical, it is not limited to a spherical shape or an ellipsoidal shape, but means that the surface is composed of a generally smooth curved surface. Also good. However, the shape is different from the shape having a corner on the surface, such as a solid formed by a crushing method.

The second phase 15 is a compound of element A and element D and is crystalline. Element D is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), Hf, Ta And at least one element selected from the group consisting of W, Re, Os, and Ir. The element D is an element that does not easily store lithium, and can form a compound that is the element A and DA _x (1 <x ≦ 3). For most of the elements A, for example, x = 2 such as FeSi ₂ or CoSi ₂ , but x = 1.33 such as Rh ₃ Si ₄ (RhSi _1.33 ), or Ru _When x = 1.5, such as ₂ Si ₃ (RuSi _1.5 ), when x = _1.67 , such as Sr ₃ Si ₅ (SrSi _1.67 ), Mn ₄ Si ₇ (MnSi _{1 .75} ) and Tc ₄ Si ₇ (TcSi _1.75 ), x = 1.75, and further IrSi ₃ may be x = 3. The second phase 15 hardly absorbs lithium.

  When nano-sized particles are prepared by applying a water-based slurry, lanthanoid elements are not preferable because they easily form hydroxides in the water-based slurry and cause separation between phases. In addition, nano-sized particles containing a lanthanoid element have a problem that they are easily hydrogenated even in plasma during formation. Note that nano-sized particles containing a lanthanoid element can be used without any problem by preventing moisture from being mixed in the plasma during the formation of the nano-sized particles or by preparing an organic solvent slurry.

  Further, the third phase 19 that is a compound of the element A and the element D may be dispersed in the first phase 13 like the nano-sized particles 17 shown in FIG. The third phase 19 is covered with the first phase 13. Similar to the second phase 15, the third phase 19 hardly absorbs lithium. Further, as shown in FIG. 2C, a part of the third phase 19 may be exposed on the surface. That is, it is not always necessary to cover the entire periphery of the third phase 19 with the first phase 13, and only a part of the periphery of the third phase 19 may be covered with the first phase 13.

  In FIG. 2B, a plurality of third phases 19 are dispersed in the first phase 13, but a single third phase 19 may be included.

  Further, the shape of the surface other than the interface of the second phase 15 may be a spherical surface whose surface is generally smooth like the second phase 15 shown in FIG. 2A, or FIG. As in the second phase 15 ′ shown in FIG. The second phase 15 ′ has a polyhedral shape due to the influence of the stability of the crystal of the compound of the elements A and D.

  Moreover, you may have two or more 2nd phases 15 like the nanosized particle 22 shown in FIG.3 (b). For example, when the ratio of the element D is small and the collision frequency between the elements D in the gas state or the liquid state decreases, the relationship between the melting points of the first phase 13 and the second phase 15, the wettability, and the cooling rate There is a case where the second phase 15 is dispersed and joined to the surface of the first phase 13 due to influence or the like.

  When the plurality of second phases 15 are provided on the first phase 13, the area of the interface between the first phase 13 and the second phase 15 is widened to further suppress the expansion and contraction of the first phase 13. Can do. In addition, when the first phase 13 is Si or Ge, the second phase 15 has higher conductivity than the first phase 13, so that the movement of electrons is promoted, and the nano-sized particles 22 are On the phase 13, each nano-sized particle 22 has a plurality of current collecting spots. Therefore, the nano-sized particles 22 become a negative electrode material having a high powder conductivity, so that the conductive auxiliary agent can be reduced and a high capacity negative electrode can be formed. Furthermore, a negative electrode having excellent high rate characteristics can be obtained.

When the element D includes two or more elements selected from the group in which the element D can be selected, the second phase 15 and / or the third phase, which is a compound of one element D and the element A 19, another element D may be contained as a solid solution or a compound. That is, even when two or more elements selected from the group capable of selecting the element D are included in the nano-sized particles, the fourth phase 25 may not be formed like the element D ′ described later. is there. For example, when the element A is Si, one element D is Ni, and the other element D is Fe, Fe may exist in NiSi ₂ as a solid solution. In addition, when observed by EDS, the Ni distribution and the Fe distribution may be almost the same or different, and another element D may be present in the second phase 15 and / or the third phase 19. It may be contained uniformly or partially.

  In addition to the element D, the nano-sized particles may include the element D ′. The element D ′ is an element selected from a group in which the element D can be selected, and the element A, the element D, and the element D ′ are different types of elements. A nano-sized particle 23 shown in FIG. 4A includes an element D and an element D ′, and has a fourth phase 25 in addition to the second phase 15 that is a compound of the element A and the element D. The fourth phase 25 is a compound of element A and element D ′. The nanosize particles 23 may include a solid solution (not shown) composed of the element D and the element D ′. For example, the second phase 15 is a compound of Si and Fe, the fourth phase 25 is a compound of Si and Co, and the solid solution composed of the elements D and D ′ is a solid solution of Fe and Co. It is done.

  Further, as shown in FIG. 4B, a third phase 19 that is a compound of the element A and the element D and a fifth phase 29 that is a compound of the element A and the element D ′ are It may be dispersed in phase 13. 4A and 4B show an example in which two types of elements are selected from the element D, three or more types of elements may be selected.

  The average particle size of these nano-sized particles is preferably 2 to 500 nm, more preferably 50 to 300 nm. According to the Hall Petch's law, if the particle size is small, the yield stress increases. Therefore, if the average particle size of the nano-sized particles is 2 to 500 nm, the particle size is sufficiently small and the yield stress is sufficiently large. It is hard to become. When the average particle size is smaller than 2 nm, it becomes difficult to handle nano-sized particles after synthesis. When the average particle size is larger than 500 nm, the particle size becomes large and the yield stress is not sufficient.

  It is preferable that the atomic ratio of the element D to the total of the element A and the element D is 0.01 to 25%. When the atomic ratio is 0.01 to 25%, both the cycle characteristics and the high capacity can be achieved when the nano-sized particles 11 are used for the negative electrode material of the nonaqueous electrolyte secondary battery. On the other hand, if it is less than 0.01%, the volume expansion of the nano-sized particles 11 during lithium occlusion cannot be suppressed, and if it exceeds 25%, the amount of element A combined with element D increases, and lithium can be occluded. The site of element A is reduced, and the merit of high capacity is particularly lost. When the nano-sized particles include the element D ′, the atomic ratio of the total of the element D and the element D ′ with respect to the total of the element A, the element D, and the element D ′ is preferably 0.01 to 25%. .

  In particular, it is preferable that the first phase is mainly crystalline silicon and the second phase is crystalline silicide. In addition, the conductivity of silicon can be increased by adding phosphorus or boron. Note that indium or gallium can be used instead of phosphorus, and arsenic can be used instead of boron. By increasing the conductivity of the first phase silicon, the negative electrode using such nano-sized particles has a low internal resistance, allows a large current to flow, and has a good high-rate characteristic.

Furthermore, by adding oxygen to the first phase Si, it is possible to suppress Si sites that are bonded to Li, and to suppress volume expansion associated with Li occlusion, thereby obtaining good life characteristics. The oxygen addition amount y is preferably in the range of SiO _y [0 ≦ y <0.9]. Under conditions where y is 0.9 or more, the number of Si sites capable of occluding Li decreases, leading to a decrease in capacity.

  Since the fine particles are usually present in an aggregated state, the average particle size of the nano-sized particles here refers to the average particle size of the primary particles. For particle measurement, image information of an electron microscope (SEM) and a volume-based median diameter of a dynamic light scattering photometer (DLS) are used in combination. For the average particle size, the particle shape is confirmed in advance using an SEM image, the particle size is obtained using image analysis software (for example, “A Image-kun” (registered trademark) manufactured by Asahi Kasei Engineering), or DLS ( For example, it can be measured by Otsuka Electronics DLS-8000). If the fine particles are sufficiently dispersed and not agglomerated, almost the same measurement results can be obtained with SEM and DLS. Even when the shape of the nano-sized particles is a highly developed structure such as acetylene black, the average particle size is defined by the primary particle size here, and the average particle size is obtained by image analysis of the SEM photograph. be able to. Further, the average particle diameter can be determined by measuring the specific surface area by the BET method or the like and assuming spherical particles. This method needs to be applied after confirming that the nano-sized particles are not porous and solid particles by SEM observation or TEM observation.

  In the case where the first phase is mainly crystalline silicon, oxygen may be bonded to the outermost surface of the nano-sized particles 11. This is because when the nano-sized particles 11 are taken out into the air, oxygen in the air reacts with elements on the surface of the nano-sized particles 11. That is, the outermost surface of the nano-sized particles 11 may have an amorphous layer having a thickness of 0.5 to 15 nm, and in particular, when the first phase is mainly crystalline silicon, it has an oxide film layer. It may be. By being covered with the amorphous layer, it is stable in the air, and an aqueous system can be used as a solvent for the slurry, which has great industrial utility value.

(2-2. Effects of nano-sized particles)
As shown in FIG. 16A, when the first phase 13 occludes lithium, the volume expands, but the second phase 15 hardly occludes lithium, so as shown in FIG. The expansion of the first phase 13 in contact with the second phase 15 is suppressed as compared with the case where the second phase 15 is not present. That is, even if the first phase 13 occludes lithium and attempts to expand the volume, the second phase 15 is difficult to expand, so the interface between the first phase 13 and the second phase 15 is difficult to slip, The phase 15 of 2 exhibits an effect like a wedge or a pin, relieves volumetric distortion, and suppresses expansion of the entire nano-sized particle. Therefore, compared with particles not having the second phase 15, the nano-sized particles 11 having the second phase 15 are less likely to expand when occlusion of lithium, and the restoring force works when lithium is released, so that the original shape is obtained. Easy to return. Therefore, according to the present invention, even when the nano-sized particles 11 occlude lithium, strain associated with volume expansion is alleviated, and a decrease in discharge capacity during repeated charge / discharge is suppressed.

  In addition, according to the present invention, the second phase 15 includes the element D and thus has high conductivity. Particularly, when the first phase 13 is Si or Ge, the conductivity of the nano-sized particles 11 as a whole is dramatically increased. To rise. Therefore, the nano-sized particles 11 have nano-level current collecting spots on the respective nano-sized particles 11, become a negative electrode material having conductivity even if there is a small amount of conductive auxiliary agent, and form a high-capacity electrode. In addition, a negative electrode having excellent high rate characteristics can be obtained.

  In addition, the nano-sized particles 17 including the third phase 19 in the first phase 13 and the nano-sized particles 27 including the third phase 19 and the fifth phase 29 are many of the first phase 13. The portion comes into contact with a phase that does not occlude lithium, and the expansion of the first phase 13 is more effectively suppressed. As a result, the nano-sized particles 17, 18, and 27 can exhibit the effect of suppressing volume expansion with a small amount of element D, can increase the amount of element A that can occlude lithium, and have high capacity and cycle characteristics. Will improve.

  The nano-sized particles 23 and 27 having both the second phase 15 and the fourth phase 25 have the same effects as the nano-sized particles 11, increase the nano-level current collecting spots, and improve the current collecting performance. Improve. When two or more kinds of D elements are added, two or more kinds of compounds are generated, and these compounds are easily separated from each other.

(2-3. Method for producing nano-sized particles)
A method for producing these nano-sized particles will be described. These nano-sized particles are synthesized by a gas phase synthesis method. In particular, these nano-sized particles can be produced by converting the raw material powder into plasma and heating it to a temperature equivalent to 10,000 K, followed by cooling. Plasma generation methods include (1) a method of inductively heating a gas using a high-frequency electromagnetic field, (2) a method of using arc discharge between electrodes, and (3) a method of heating a gas by using a microwave. Any of these can be used.
That is, since the element D is an element that forms a compound with the element A, when the raw material powder is cooled after being plasmatized, a part of the element A forms a compound with the element D, and the remaining element A is a simple substance or Precipitate as a solid solution. Therefore, it is possible to obtain a so-called dharma-shaped nano-sized particle 11 in which the second phase, which is a compound of the element A and the element D, is bonded to the first phase of the element A alone or in a solid solution via the interface.

  As a specific example of a manufacturing apparatus used for manufacturing nano-sized particles, (1) a method of inductively heating a gas using a high-frequency electromagnetic field will be described with reference to FIG. In the nanosize particle manufacturing apparatus 31 shown in FIG. 5, a high frequency coil 47 for generating plasma is wound around the upper outer wall of the reaction chamber 45. An AC voltage of several MHz is applied to the high frequency coil 47 from a high frequency power source 49. A preferred frequency is 4 MHz. The upper outer wall around which the high-frequency coil 47 is wound is a cylindrical double tube made of quartz glass or the like, and cooling water is passed through the gap to prevent the quartz glass from melting by plasma.

  A sheath gas supply port 39 is provided in the upper part of the reaction chamber 45 together with the raw material powder supply port 35. The raw material powder 37 supplied from the raw material powder feeder is supplied into the plasma 51 through the raw material powder supply port 35 together with the carrier gas 43 (rare gas such as helium and argon). The sheath gas 41 is supplied to the reaction chamber 45 through the sheath gas supply port 39. The sheath gas 41 is a mixed gas of argon gas and oxygen gas or the like. Note that the raw material powder supply port 35 is not necessarily installed above the plasma 51 as shown in FIG. 5, and a nozzle can be installed in the lateral direction of the plasma 51. The raw material powder supply port 35 may be water-cooled with cooling water. In addition, the property of the raw material of the nanosize particles supplied to the plasma is not limited to the powder, and a slurry of the raw material powder or a gaseous raw material may be supplied.

  The reaction chamber 45 plays a role of holding the pressure of the plasma reaction part and suppressing the dispersion of the produced fine powder. The reaction chamber 45 is also water-cooled to prevent damage due to plasma. A suction tube is connected to the side of the reaction chamber 45, and a filter 53 for collecting the synthesized fine powder is installed in the middle of the suction tube. The suction pipe connecting the filter 53 from the reaction chamber 45 is also water-cooled with cooling water. The pressure in the reaction chamber 45 is adjusted by the suction capacity of a vacuum pump (VP) installed on the downstream side of the filter 53.

  The manufacturing method of the nano-sized particle 11 is a bottom-up method in which the nano-sized particle 11 is deposited from plasma to a solid via a gas and a liquid, so that the nano-sized particle 11 is formed into a spherical shape at the droplet stage. Become. On the other hand, in the top-down method of reducing large particles such as the crushing method and the mechanochemical method, the shape of the particles is rugged and very different from the spherical shape of the nano-sized particles 11.

When a mixed powder of the element A powder and the element D powder is used as the raw material powder, nano-sized particles 11, 17, 18, 21, and 22 are obtained. Further, when a mixed powder of powders of element A, element D and element D ′ is used as the raw material powder, nano-sized particles 23 and 27 are obtained. Furthermore, when oxygen is introduced into the first phase 13, for example, the composition ratio can be easily controlled by introducing the element A and its oxide AO ₂ or the like as powders such as Si and SiO _2. .

(3. Nano-sized particles according to the second embodiment)
(3-1. Configuration of Nano-sized Particle 61)
The nanosize particles 61 according to the second embodiment will be described.
FIG. 6 is a schematic cross-sectional view showing the nano-sized particles 61. The nano-sized particle 61 has a sixth phase 63 and a seventh phase 65, and both the sixth phase 63 and the seventh phase 65 are exposed on the outer surface of the nano-sized particle 61. The interface between the sixth phase 63 and the seventh phase 65 is a flat surface or a curved surface, and the sixth phase 63 and the seventh phase 65 are joined via the interface, and the other surfaces are substantially spherical. Having a surface.

  The sixth phase 63 is composed of a single element or a solid solution of the element A, and the element A is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn. is there. The element A is an element that easily stores lithium. The element that forms a solid solution with the element A may be an element selected from the group in which the element A can be selected, or an element not listed in the group. The sixth phase 63 can occlude and desorb lithium.

  The other than the interface between the sixth phase 63 and the seventh phase 65 is substantially spherical. The sixth phase 63 and the seventh phase other than the interface where the sixth phase 63 and the seventh phase 65 are in contact with each other. 65 means a sphere or an ellipsoid. In other words, it means that the surfaces of the sixth phase 63 and the seventh phase 65 other than the portion where the sixth phase 63 and the seventh phase 65 are in contact are generally formed of a smooth curved surface. The shapes of the sixth phase 63 and the seventh phase 65 mean shapes different from shapes having corners on the surface such as a solid formed by a crushing method. Further, the interface shape of the joint portion between the sixth phase 63 and the seventh phase 65 is circular or elliptical.

  The seventh phase 65 is a compound of the element A and the element M, or a simple substance or a solid solution of the element M, and is crystalline. The element M is at least one element selected from the group consisting of Cu, Ag and Au. The element M is an element that hardly stores lithium, and the seventh phase 65 hardly stores lithium.

If the element A and the element M are combinations capable of forming a compound, the seventh phase 65 is formed from MA _x (x ≦ 1, 3 <x) which is a compound of the element A and the element M. On the other hand, if the combination of the element A and the element M does not form a compound, the seventh phase 65 becomes a simple substance or a solid solution of the element M.

  For example, when the element A is Si and the element M is Cu, the seventh phase 65 is formed of copper silicide that is a compound of the element M and the element A.

  For example, when the element A is Si and the element M is Ag or Au, the seventh phase 65 is formed of a single element of the element M or a solid solution containing the element M as a main component.

In particular, the sixth phase 63 is preferably crystalline silicon. In addition, the conductivity of silicon can be increased by adding phosphorus or boron. Indium or gallium can be used instead of phosphorus, and arsenic can be used instead of boron. By increasing the conductivity of the silicon of the sixth phase 63, the negative electrode using such nano-sized particles has a low internal resistance, allows a large current to flow, and has a good high-rate characteristic. Moreover, the 6th phase 63 can suppress the site | part which reacts with lithium by containing oxygen. When oxygen is included, the capacity decreases, but volume expansion accompanying lithium occlusion can be suppressed. The amount z of oxygen added is preferably in the range of AO _z (0 <z <1). When z is 1 or more, the Li occlusion site of A is suppressed and the capacity is reduced.

  The average particle size of the nano-sized particles 61 is preferably 2 to 500 nm, more preferably 50 to 200 nm. According to Hall Petch's law, yield stress increases when the particle size is small. Therefore, if the average particle size of the nano-sized particles 61 is 2 to 500 nm, the particle size is sufficiently small, the yield stress is sufficiently large, and pulverized by charge / discharge. Hateful. When the average particle size is smaller than 2 nm, it is difficult to handle nano-sized particles after synthesis. When the average particle size is larger than 500 nm, the particle size becomes large and the yield stress is not sufficient.

  The atomic ratio of the element M in the total of the element A and the element M is preferably 0.01 to 60%. When the atomic ratio is 0.01 to 60%, both the cycle characteristics and the high capacity can be achieved when the nano-sized particles 61 are used for the negative electrode material of the nonaqueous electrolyte secondary battery. On the other hand, if it is less than 0.01%, the volume expansion of the nano-sized particles 61 during occlusion of lithium cannot be sufficiently suppressed, and if it exceeds 60%, the merit of high capacity is particularly lost.

  Note that the nano-sized particles 61 according to the second embodiment may have an eighth phase 69 like the nano-sized particles 67 illustrated in FIG. The nano-sized particle 67 further includes an element M ′ selected from the group consisting of Cu, Ag, and Au, and the element M ′ is different from the element M in kind. The eighth phase 69 is a compound of the element A and the element M ′ or a simple substance or a solid solution of the element M ′. For example, the element A is Si, the element M is Cu, and the element M ′ is Ag, the sixth phase 63 is a simple substance or a solid solution of silicon, the seventh phase 65 is copper silicide, and the eighth phase 69 is silver. And nano-sized particles 67 that are a simple substance or a solid solution.

  The sixth phase 63, the seventh phase 65, and the eighth phase 69 are all exposed on the outer surface, and the sixth phase 63, the seventh phase 65, and the eighth phase 69 are substantially spherical except for the interface. It is. For example, the nano-sized particle 67 has a shape like a water molecule in which the seventh phase 65 and the eighth phase 69 having a small spherical shape are joined to the surface of the sixth phase 63 having a large spherical shape. Have. Moreover, it is preferable that the total atomic ratio of the element M and the element M ′ in the total of the element A, the element M, and the element M ′ is 0.01 to 60%.

Note that, when the sixth phase is mainly crystalline silicon, oxygen may be bonded to the outermost surface of the nano-sized particles 61. This is because when the nanosize particles 61 are taken out into the air, oxygen in the air reacts with elements on the surface of the nanosize particles 61. That is, the outermost surface of the nano-sized particles 61 may have an amorphous oxide film having a thickness of 0.5 to 15 nm. Furthermore, oxygen is stabilized in the air by introducing it into the sixth phase 63 in the range of AO _z (0 <z <1), and an aqueous system can be used as a solvent for the slurry, which has industrial utility value. large.

(3-2. Effects of Second Embodiment)
According to the second embodiment, when the sixth phase 63 occludes lithium, the sixth phase 63 expands in volume, but the seventh phase 65 does not occlude lithium, and thus the sixth phase 63 at a position in contact with the seventh phase 65. The expansion of is suppressed. That is, even if the sixth phase 63 occludes lithium and attempts to expand volume, the seventh phase 65 hardly expands, so the interface between the sixth phase 63 and the seventh phase 65 is difficult to slip, 7 phase 65 exhibits an effect like a wedge or a pin, relieves volumetric distortion, and suppresses the expansion of the entire nano-sized particle. Therefore, compared with particles not having the seventh phase 65, the nano-sized particles 61 having the seventh phase 65 are less likely to expand when occludes lithium, and the restoring force works when lithium is released, resulting in an original shape. Easy to return. Therefore, according to 2nd Embodiment, even if the nanosized particle 61 occludes lithium, volume expansion is suppressed and the fall of the discharge capacity at the time of repeated charging / discharging is suppressed.

  Further, according to the second embodiment, since the seventh phase 65 includes the element M, the seventh phase 65 has higher conductivity than the sixth phase 63. Therefore, the nano-sized particles 61 have nano-level current collecting spots on each nano-sized particle 61, and the nano-sized particles 61 become a negative electrode material with good conductivity, and a negative electrode with good current collecting performance is obtained.

  The nano-sized particle 67 having both the seventh phase 65 and the eighth phase 69 has the same effect as the nano-sized particle 61, and the nano-level current collecting spots are increased, and the current collecting performance is effectively improved. improves.

(4. Third embodiment)
(4-1. Configuration of Nano-sized Particle 71)
A nanosize particle 71 according to the third embodiment will be described. In the following embodiment, the same number is attached | subjected to the element which fulfill | performs the same aspect as 2nd Embodiment, and the duplicate description is avoided.
FIG. 7A is a schematic cross-sectional view of the nanosize particle 71. The nano-sized particle 71 has a sixth phase 63, a seventh phase 65, and a ninth phase 73, and the sixth phase 63 and the seventh phase 65 are joined via an interface, The sixth phase 63 and the ninth phase 73 are joined via an interface. Further, the sixth phase 63, the seventh phase 65, and the ninth phase 73 are exposed on the outer surface of the nano-sized particles 71, and the sixth phase 63, the seventh phase 65, and the ninth phase are exposed. 73 has a substantially spherical surface except for the interface.

The ninth phase 73 is a compound of the element A and the element D, has high conductivity, and is crystalline. Element D is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), Hf, Ta And at least one element selected from the group consisting of W, Re, Os, and Ir. The element D is an element that does not easily store lithium, and can form a compound that is the element A and DA _y (1 <y ≦ 3). The ninth phase 73 hardly absorbs or absorbs little lithium.

  It is preferable that the atomic ratio of the element D in the total of the element A and the element D is 0.01 to 25%. When the atomic ratio is 0.01 to 25%, when nano-sized particles are used as a negative electrode material for a nonaqueous electrolyte secondary battery, both cycle characteristics and high capacity can be achieved. On the other hand, if the amount is less than 0.01%, the volume expansion of the nano-sized particles during occlusion of lithium cannot be suppressed, and if the amount exceeds 25%, the amount of element A combined with element D increases, and the element capable of occluding lithium The site of A is reduced and the merit of high capacity is particularly lost. As will be described later, when the nano-sized particles contain the element D ′, the total atomic ratio of the element D and the element D ′ in the total of the element A, the element D, and the element D ′ is 0.01 to 25%. It is preferable that

  Further, the nano-sized particle 71 according to the third embodiment has a tenth phase 77 that is a compound of the element A and the element D, like the nano-sized particle 75 shown in FIG. It may be dispersed in phase 63. The tenth phase 77 is covered with the sixth phase 63. The tenth phase 77, like the seventh phase 65, hardly or even occludes lithium.

  In FIG. 7B, a plurality of tenth phases 77 are dispersed in the sixth phase 63, but a single tenth phase 77 may be included.

  Further, a part of the tenth phase 77 may be exposed on the surface like the nano-sized particles 76 shown in FIG. That is, it is not always necessary to cover the entire periphery of the tenth phase 77 with the sixth phase 63, and only a part of the periphery of the tenth phase 77 may be covered with the sixth phase 63.

  Further, the nano-sized particles 71 and 75 according to the third embodiment include an eighth phase 69 like the nano-sized particle 79 illustrated in FIG. 8A and the nano-sized particle 81 illustrated in FIG. You may have. The nano-sized particles 79 and 81 further include an element M ′ selected from the group consisting of Cu, Ag and Au, and the element M ′ is different from the element M in kind. The eighth phase 69 is a compound of the element A and the element M ′ or a simple substance or a solid solution of the element M ′.

When the element D includes two or more elements selected from the group in which the element D can be selected, the ninth phase 73 and / or the tenth phase, which is a compound of one element D and the element A 77, another element D may be contained as a solid solution or a compound. That is, even when two or more elements selected from the group capable of selecting the element D are included in the nano-sized particles, the eleventh phase 85 may not be formed like the element D ′ described later. is there. For example, when the element A is Si, one element D is Ni, and the other element D is Fe, Fe may exist in NiSi ₂ as a solid solution. Further, when observed by EDS, the Ni distribution and Fe distribution may be almost the same or different, and another element D may be present in the ninth phase 73 and / or the tenth phase 77. It may be contained uniformly or partially.

  Further, the nano-sized particle 71 according to the third embodiment includes an element D and an element D ′ as in the nano-sized particle 83 illustrated in FIG. 85 may be formed. The eleventh phase 85 is a compound of element A and element D ′. The eleventh phase 85 is bonded to the sixth phase 63 via the interface, and is exposed on the outer surface. For example, the element A is silicon, the element D is iron, the element D ′ is cobalt, the sixth phase 63 is a simple substance or a solid solution of silicon, the ninth phase 73 is iron silicide, 11 phase 85 is cobalt silicide. In this case, a solid solution of iron and cobalt may be formed in the sixth phase 63.

  The element D ′ is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, a lanthanoid element (except Pm), Hf , Ta, W, Re, Os, Ir, and a different kind of element from the element D.

  Further, the nano-sized particle 83 according to the third embodiment includes the element D and the element D ′ as in the nano-sized particle 87 shown in FIG. And a twelfth phase 89 that is a compound of the element A and the element D ′ may be dispersed in the sixth phase 63. The twelfth phase 89 is covered with the sixth phase 63. The twelfth phase 89, like the eleventh phase 85, hardly or does not occlude lithium.

  Further, the shape of the surface other than the interface between the ninth phase 73 and the eleventh phase 85 is similar to the ninth phase 73 shown in FIG. 7A and the eleventh phase 85 shown in FIG. In addition, the surface may be a generally smooth spherical surface, or may be a polyhedral shape such as the ninth phase 73 ′ and the eleventh phase 85 ′ of the nano-sized particles 91 shown in FIG. 10. The ninth phase 73 ′ and the eleventh phase 85 ′ have a polyhedral shape due to the influence of the crystal of the compound of the element A and the element D.

  A plurality of nano-sized particles may be bonded to each other through the ninth phase 73 and the eleventh phase 85 to form a joined body. In addition, some nano-sized particles may be divided from the composite in which the nano-sized particles are bonded to each other, and the bonded portion may have a polyhedral shape.

(4-2. Effects of the third embodiment)
According to the third embodiment, in addition to the effects obtained in the second embodiment, the nano-sized particles 71 are not easily pulverized even when lithium is occluded. In the third embodiment, when the sixth phase 63 occludes lithium, the volume expands, but the seventh phase 65 and the ninth phase 73 hardly occlude lithium. The expansion of the sixth phase 63 in contact with the nine phases 73 is suppressed. That is, even if the sixth phase 63 occludes lithium to expand the volume, the seventh phase 65 and the ninth phase 73 are unlikely to expand, so the sixth phase 63 and the seventh phase 65 or the The interface of the ninth phase 73 is difficult to slip, and the seventh phase 65 and the ninth phase 73 exhibit an effect like a wedge or a pin, relieve the volume distortion, and suppress the expansion of the entire nano-sized particle. Therefore, compared with particles that do not have the ninth phase 73, the nano-sized particles 71 having the ninth phase 73 are less likely to expand when occludes lithium, and the restoring force works during the release of lithium to return to the original shape. Easy to return. Therefore, even when the nano-sized particles 71 occlude and release lithium, the strain associated with volume expansion is relaxed, and a decrease in discharge capacity during repeated charge / discharge is suppressed.

  In addition, since the nano-sized particles 75 and the nano-sized particles 81 including the tenth phase 77 in the sixth phase 63 are in contact with a phase that does not occlude lithium, most of the sixth phase 63 is less in number. In the phase 77, the expansion of the sixth phase 63 is effectively suppressed. As a result, even if the nanosized particles 75 and 81 occlude lithium, the volume expansion is suppressed, and the decrease in the discharge capacity during repeated charge and discharge is further suppressed.

  The nano-sized particles 79 and the nano-sized particles 81 having both the seventh phase 65 and the eighth phase 69 have the same effect as the nano-sized particles 61, and the nano-level current collecting spots are increased. Performance is improved effectively. Therefore, the high rate characteristic is improved.

  Similarly, the nano-sized particles 83 and the nano-sized particles 87 having both the ninth phase 73 and the eleventh phase 85 have the same effect as the nano-sized particles 61 and increase the nano-level current collecting spots. The current collection performance is effectively improved. Therefore, the high rate characteristic is improved.

  In addition, the nanosized particle 87 including the tenth phase 77 and the twelfth phase 89 in the sixth phase 63 is a phase in which most of the sixth phase 63 does not occlude lithium or a phase in which only a small amount of lithium is occluded. Therefore, the expansion of the sixth phase 63 is further suppressed. As a result, the nano-sized particles 87 are further suppressed from lowering the discharge capacity during repeated charge / discharge and improve the high rate characteristics.

(5. Manufacturing method of nano-sized particles according to second and third embodiments)
A method for producing nanosized particles according to the present invention will be described. The nano-sized particles according to the present invention are synthesized by a gas phase synthesis method. In particular, nano-sized particles can be produced by converting the raw material powder into plasma and heating it to the equivalent of 10,000 K, followed by cooling. Plasma generation methods include (1) a method of inductively heating a gas using a high-frequency electromagnetic field, (2) a method of using arc discharge between electrodes, and (3) a method of heating a gas by using a microwave. Any of these can be used.
That is, when the element M is an element that forms a compound with the element A, when the raw material powder is cooled after being converted to plasma, a part of the element A forms a compound with the element M, and the remaining element A is a simple substance or Precipitate as a solid solution. Further, when the element M is an element that does not form a compound with the element A, when the raw material powder is cooled after being plasmatized, the element M and the element A are separately deposited as a single substance or a solid solution. Therefore, a so-called Dalma-shaped nano-sized particle in which the element A and the sixth phase of the solid solution or the seventh phase of the element A and the compound of the element M or the element M or the element M are joined via the interface. 61 can be obtained.

  A specific example of a production apparatus used for producing nanosize particles is a nanosize particle production apparatus 31 shown in FIG.

  The nano-sized particle manufacturing method is a bottom-up method in which a nano-sized particle is deposited from plasma through a gas or liquid, so that the nano-sized particle is formed into a spherical shape at the stage of droplets, and the sixth phase 63 and the seventh phase. 65 becomes a substantially spherical shape. On the other hand, since the crushing method and the mechanochemical method are top-down methods for reducing large particles, the shape of the particles is rugged and is significantly different from the spherical shape of the nano-sized particles 61.

Thereafter, the produced nano-sized particles can be heated in the atmosphere to promote the oxidation of the nano-sized particles. For example, the nano-sized particles can be oxidized and stabilized by heating at 250 ° C. for 1 hour in the air. Moreover, lifetime characteristics can be improved while suppressing initial capacity by intentionally introducing oxygen into the sixth phase as AO _z (0 <z <1). For example, the composition ratio can be easily controlled by introducing Si and its oxide SiO ₂ as the element A.

  In addition, when the mixed powder of the powder of the element A and the powder of the element M is used for raw material powder, the nanosized particle 61 which concerns on 2nd Embodiment is obtained. On the other hand, when the mixed powder of each powder of the element A, the element M, and the element D is used for the raw material powder, the nano-sized particles 71 according to the third embodiment are obtained. Moreover, when the mixed powder of each powder of the element A, the element M, the element M ', and the element D is used for raw material powder, the nanosized particle 79 which concerns on 3rd Embodiment is obtained. Moreover, when the mixed powder of each powder of the element A, the element M, the element D, and the element D ′ is used for the raw material powder, the nano-sized particles 83 according to the third embodiment are obtained.

(6. Nano-sized particles according to the fourth embodiment)
(6-1. Configuration of Nano-sized Particles According to Fourth Embodiment)
A nanosize particle 101 according to the fourth embodiment will be described.
FIG. 11A is a schematic cross-sectional view of the nano-sized particle 101. The nano-sized particle 101 has a thirteenth phase 103, a fourteenth phase 105, and a fifteenth phase 107. The thirteenth phase 103, the fourteenth phase 105, and the fifteenth phase 107 It is exposed on the outer surface of the size particle 101, and the outer surface other than the interfaces of the thirteenth phase 103, the fourteenth phase 105, and the fifteenth phase 107 is substantially spherical, and the thirteenth phase 103 and the fourteenth phase. The phase 105 is bonded via an interface, and the thirteenth phase 103 and the fifteenth phase 107 are bonded via an interface.

  The thirteenth phase 103 is a simple substance of the element A-1, and the element A-1 is one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn. is there. The element A-1 is an element that easily stores lithium. Note that the thirteenth phase 103 may be a solid solution containing the element A-1 as a main component. The element that forms a solid solution with the element A-1 may be an element selected from the group capable of selecting the element A-1 or an element not listed in the group. The thirteenth phase 103 can occlude and desorb lithium. The interface between the thirteenth phase 103 and the fourteenth phase 105 is a plane or a curved surface. The interface between the thirteenth phase 103 and the fifteenth phase 107 is a plane or a curved surface. Further, the fourteenth phase 105 and the fifteenth phase 107 may be bonded via an interface.

  That the outer surface other than the interface between the thirteenth phase 103 and the fourteenth phase 105 is substantially spherical is that the thirteenth phase 103 other than the interface between the thirteenth phase 103 and the fourteenth phase 105 and the 14 phases 105 means a sphere or an ellipsoid. In other words, the phases of the 13th phase 103 and the 14th phase 105 other than the portion where the 13th phase 103 and the 14th phase 105 are in contact with each other. It means that the surface is composed of a generally smooth curved surface. The shapes of the thirteenth phase 103 and the fourteenth phase 105 are different from shapes having a corner on the surface, such as a solid formed by a crushing method. The same applies to the fifteenth phase 107. Further, the interface shape of the joint portion of the thirteenth phase 103 and the fourteenth phase 105 and the interface shape of the joint portion of the thirteenth phase 103 and the fifteenth phase 107 are circular or elliptical.

  The fourteenth phase 105 is a single element or a solid solution of the element A-2. The element A-2 is one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, and is a different element from the element A-1. The element A-2 can occlude and desorb Li.

In addition, the conductivity of silicon can be increased by adding phosphorus or boron. Indium or gallium can be used instead of phosphorus, and arsenic can be used instead of boron. By increasing the conductivity of the silicon of the thirteenth phase 103, the negative electrode using such nano-sized particles has a low internal resistance, allows a large current to flow, and has a good high-rate characteristic. In addition, the thirteenth phase 103 can suppress sites that react with lithium by containing oxygen. When oxygen is included, the capacity decreases, but volume expansion accompanying lithium occlusion can be suppressed. The amount z of oxygen added is preferably in the range of AO _z (0 <z <1). When z is 1 or more, the Li occlusion site of A is suppressed and the capacity is reduced.

The fifteenth phase 107 is a compound of the element A-1 and the element D and is crystalline. Element D is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), Hf, Ta And at least one element selected from the group consisting of W, Re, Os, and Ir. The element D is an element that hardly absorbs lithium, and can form a compound that is the elements A-1 and D (A-1) _y (1 <y ≦ 3). For most of the elements A-1, for example, x = 2 such as FeSi ₂ and CoSi ₂ , but x = 1.33 such as Rh ₃ Si ₄ (RhSi _1.33 ) When x = 1.5, such as Ru ₂ Si ₃ (RuSi _1.5 ), when x = _1.67 , such as Sr ₃ Si ₅ (SrSi _1.67 ), Mn ₄ Si ₇ ( When x = 1.75 such as MnSi _1.75 ) or Tc ₄ Si ₇ (TcSi _1.75 ), x = ₃ may be further provided such as IrSi ₃ . The fifteenth phase 107 hardly or even occludes lithium.

  The average particle size of the nano-sized particles 101 is preferably 2 to 500 nm, more preferably 50 to 300 nm. According to Hall Petch's law, if the particle size is small, the yield stress increases. Therefore, if the average particle size of the nano-sized particles 101 is 2 to 500 nm, the particle size is sufficiently small, the yield stress is sufficiently large, and pulverized by charge / discharge. Hateful. When the average particle size is smaller than 2 nm, it is difficult to handle nano-sized particles after synthesis. When the average particle size is larger than 500 nm, the particle size becomes large and the yield stress is not sufficient.

  It is preferable that the atomic ratio of the element D in the total of the element A-1, the element A-2, and the element D is 0.01 to 25%. When the atomic ratio is 0.01 to 25%, both the cycle characteristics and the high capacity can be achieved when the nano-sized particles 101 are used as the negative electrode material of the nonaqueous electrolyte secondary battery. On the other hand, if the amount is less than 0.01%, the volume expansion of the nano-sized particles 101 during the occlusion of lithium cannot be suppressed, and if the amount exceeds 25%, the amount of the element A-1 combined with the element D increases, The number of possible sites for element A-1 is reduced, and the merit of high capacity is particularly lost. As will be described later, when the nano-sized particles contain the element D ′, the atomic ratio of the total of the element D and the element D ′ in the total of the element A-1, the element A-2, the element D, and the element D ′ Is preferably 0.01 to 25%.

  In addition, as in the nano-sized particle 109 shown in FIG. 11B, the sixteenth phase 111 that is a compound of the element A-1 and the element D may be dispersed in the thirteenth phase 103. The sixteenth phase 111 is covered with the thirteenth phase 103. As in the fifteenth phase 107, the sixteenth phase 111 hardly absorbs lithium. Further, as shown in FIG. 11C, a part of the sixteenth phase 111 may be exposed on the surface. That is, it is not always necessary to cover the entire periphery of the sixteenth phase 111 with the thirteenth phase 103, and only a part of the periphery of the sixteenth phase 111 may be covered with the thirteenth phase.

  In FIG. 11B, a plurality of sixteenth phases 111 are dispersed in the thirteenth phase 103, but a single sixteenth phase 111 may be included.

  In addition, as in the nano-sized particle 113 shown in FIG. 12A, the seventeenth phase 115 that is a compound of the element A-1 and the element D is bonded to the fourteenth phase 105 via the interface, and the outer It may be exposed on the surface. Like the fifteenth phase 107, the seventeenth phase 115 hardly occludes lithium.

  Further, the shape of the surface other than the interface of the fifteenth phase 107 may be a spherical surface whose surface is generally smooth like the fifteenth phase 107 shown in FIG. 11 (a), or FIG. 12 (b). As in the fifteenth phase 107 ′ shown in FIG. The polyhedron shape is formed by peeling off after the nano-sized particles 101, 109, 110, 113 or 117 are bonded via the fifteenth phase.

  Further, the nano-sized particle 101 according to the present invention may have an eighteenth phase 121 in addition to the fourteenth phase 105 like the nano-sized particle 119 shown in FIG. The eighteenth phase 121 is a single element or a solid solution of the element A-3, and the element A-3 is one kind selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn. It is an element and is a different kind of element from the element A-1 and the element A-2. The eighteenth phase 121 has a spherical outer surface and is exposed on the outer surface of the nano-sized particles 119. For example, silicon can be used as the element A-1, tin can be used as the element A-2, and aluminum can be used as the element A-3. In addition, as in the nano-sized particles 123 illustrated in FIG. 13B, the sixteenth phase 111 that is a compound of the element A-1 and the element D may be dispersed in the thirteenth phase 103.

When the element D includes two or more elements selected from the group in which the element D can be selected, the fifteenth phase 107 and / or the sixteenth compound which is a compound of one element D and the element A-1 In the phase 111, another element D may be contained as a solid solution or a compound. That is, even when two or more elements selected from the group capable of selecting the element D are included in the nano-sized particles, the nineteenth phase 127 may not be formed like the element D ′ described later. is there. For example, when the element A-1 is Si, one element D is Ni, and the other element D is Fe, Fe may exist as a solid solution in NiSi ₂ . In addition, when observed by EDS, the Ni distribution and Fe distribution may be approximately the same or different, and another element D may be present in the fifteenth phase 107 and / or the sixteenth phase 111. It may be contained uniformly or partially.

  In addition to the element D, the nano-sized particles may include the element D ′. The element D ′ is an element selected from a group in which the element D can be selected, and the element D and the element D ′ are different types of elements. A nanosize particle 125 shown in FIG. 14A includes an element D and an element D ′, and has a nineteenth phase 127 in addition to the fifteenth phase 107 which is a compound of the element A-1 and the element D. The nineteenth phase 127 is a compound of the element A-1 and the element D ′. The nano-sized particle 125 may include a solid solution (not shown) composed of the element D and the element D ′. For example, the fifteenth phase 107 is a compound of Si and Fe, the nineteenth phase 127 is a compound of Si and Co, and the solid solution composed of the elements D and D ′ is a solid solution of Fe and Co. It is done.

  Further, like a nano-sized particle 129 shown in FIG. 14B, a sixteenth phase 111 which is a compound of the element A-1 and the element D, a compound of the element A-1 and the element D ′, and the twentieth The phase 131 may be dispersed in the thirteenth phase 103. Further, the sixteenth phase 111 or the twentieth phase 131 may be exposed on the surface as shown in FIG.

  Note that oxygen may be bonded to the outermost surface of the nano-sized particle 101. This is because oxygen in the air reacts with elements on the surface of the nanosize particles 101 when the nanosize particles 101 are taken out into the air. That is, the outermost surface of the nano-sized particles 101 may have an amorphous layer having a thickness of 0.5 to 15 nm, and in particular, when the 13th phase is mainly crystalline silicon, it has an oxide film layer. It may be.

(6-2. Effect of Nano-sized Particles According to Fourth Embodiment)
According to the present invention, when the thirteenth phase 103 occludes lithium, the volume expands, but the fourteenth phase 105 also expands when occludes lithium. However, since the electrochemical potential for storing lithium is different between the thirteenth phase 103 and the fourteenth phase 105, when one phase occludes lithium preferentially and one phase undergoes volume expansion, the other phase The volume expansion of the other phase is relatively small, and the other phase makes it difficult for the one phase to undergo volume expansion. Therefore, compared with particles having only one phase, the nano-sized particles 101 having the thirteenth phase 103 and the fourteenth phase 105 are less likely to expand when occlusion of lithium, and the occlusion amount of lithium is suppressed. . Therefore, according to the present invention, even if the nanosized particles 101 occlude lithium, volume expansion is suppressed, and a decrease in discharge capacity during repeated charge / discharge is suppressed.

  In addition, when the thirteenth phase 103 occludes lithium, the volume expands, but the fifteenth phase 107 hardly absorbs lithium, and therefore the expansion of the thirteenth phase 103 in contact with the fifteenth phase 107 is suppressed. . That is, even if the thirteenth phase 103 occludes lithium and expands its volume, the fifteenth phase 107 hardly expands, so the interface between the thirteenth phase 103 and the fifteenth phase 107 is difficult to slip, The 15 phases 107 exert an effect like a wedge or a pin, relieve the volume strain, and suppress the expansion of the entire nano-sized particles. Therefore, compared with particles that do not have the fifteenth phase 107, the nanosized particles 101 that have the fifteenth phase 107 are less likely to expand when occludes lithium, and a restoring force works during lithium release to return to the original shape. Easy to return. The amount of occlusion of lithium is suppressed. Therefore, according to the present invention, even when the nano-sized particles 101 occlude lithium, strain associated with volume expansion is alleviated, and a decrease in discharge capacity during repeated charge / discharge is suppressed.

  In addition, according to the present invention, since the nano-sized particles 101 are difficult to expand, even if the nano-sized particles 101 are put out into the atmosphere, they hardly react with oxygen in the atmosphere. When nanosized particles having only one phase are left in the atmosphere without surface protection, they react with oxygen from the surface, and oxidation proceeds from the surface to the inside of the particles, so that the entire nanosized particles are oxidized. However, when the nano-sized particles 101 of the present invention are left in the atmosphere, the outermost surface of the particles reacts with oxygen, but the nano-sized particles are difficult to expand as a whole, so that it is difficult for oxygen to enter the interior. Oxidation does not easily reach the center of 101. Therefore, normal metal nanoparticles have a large specific surface area and are likely to oxidize and generate heat and volume expansion, but the nano-sized particles 101 of the present invention do not need to be specially coated with organic substances or metal oxides. It can be handled as a powder in the atmosphere and has great industrial utility value.

  In addition, according to the present invention, the 13th phase 103 and the 14th phase 105 are both composed of an element capable of occluding a larger amount of lithium than carbon. The amount of occlusion of lithium is greater than that of the substance.

  In addition, according to the present invention, when the fourteenth phase 105 has higher conductivity than the thirteenth phase 103, the nanosize particles 101 have nano-level current collecting spots on the respective nanosize particles 101, The nano-sized particles 101 become a negative electrode material with good conductivity, and a negative electrode with good current collecting performance can be obtained. In particular, in the case where the thirteenth phase 103 is formed of silicon having low conductivity, the fourteenth phase 105 is conductive compared to silicon nanoparticles by using a metal element such as tin or aluminum having higher conductivity than silicon. A negative electrode material with good properties can be obtained.

  In addition, since the nano-sized particles 109 including the sixteenth phase 111 in the thirteenth phase 103 are in contact with a phase in which a large part of the thirteenth phase 103 hardly stores lithium, the expansion of the thirteenth phase 103 is caused. More suppressed. As a result, even if the nanosized particles 109 occlude lithium, volume expansion is suppressed, and a decrease in discharge capacity due to repeated charge and discharge is further suppressed.

  Nano-sized particles 119 and 123 having fourteenth phase 105, fifteenth phase 107 and eighteenth phase 121, and nano-sized particles 125 having fourteenth phase 105, fifteenth phase 107 and nineteenth phase 127 And 129, the nano-level current collection spot is increased, and the current collection performance is effectively improved.

  Further, the nano-sized particles 123 including the sixteenth phase 111 in the thirteenth phase 103 and the nano-sized particles 129 including the sixteenth phase 111 and the twentieth phase 131 in the thirteenth phase 103 are the thirteenth. Since many portions of the phase 103 are in contact with a phase that does not occlude lithium, expansion of the thirteenth phase 103 is further suppressed. As a result, even if the nanosized particle 123 and the nanosized particle 129 occlude lithium, the volume expansion is suppressed, and a decrease in discharge capacity due to repeated charge and discharge is further suppressed.

(6-3. Method for producing nano-sized particles)
A method for producing nano-sized particles will be described.
Nano-sized particles are synthesized by a gas phase synthesis method. In particular, nano-sized particles can be produced by converting the raw material powder into plasma and heating it to the equivalent of 10,000 K, followed by cooling. Plasma generation methods include (1) a method of inductively heating a gas using a high-frequency electromagnetic field, (2) a method of using arc discharge between electrodes, and (3) a method of heating a gas by using a microwave. Any of these can be used.
That is, the element D is an element that forms a compound with the element A-1, and the element A-1 and the element A-2 do not form a compound. A-1 forms a compound with the element M, and the remaining element A-1 and element A-2 precipitate as a simple substance or a solid solution. Therefore, the 14th phase of element A-2 alone or solid solution and the 15th phase, which is a compound of element A-1 and element D, interface with the 13th phase of element A-1 alone or solid solution. The nano-sized particles 101 joined through the intermediate layer can be obtained.

  A specific example of a production apparatus used for producing nanosize particles is a nanosize particle production apparatus 31 shown in FIG.

  The method for producing nano-sized particles is a bottom-up method in which the nano-sized particles are solidified via plasma and gas and liquid and precipitate nano-sized particles. The phase 105 has a spherical shape. On the other hand, in the crushing method and the mechanochemical method, in the top-down method in which large particles are reduced, the shape of the particles is rugged, which is significantly different from the spherical shape of the nano-sized particles 101.

  In addition, when the mixed powder of each powder of the element A-1, the element A-2, and the element D is used for the raw material powder, nano-sized particles 101, 109, 113, 117 according to the present invention are obtained. On the other hand, when mixed powders of the respective powders of element A-1, element A-2, element A-3 and element D are used as the raw material powder, nano-sized particles 119 and 23 are obtained. Further, when a mixed powder of the powders of the element A-1, the element A-2, the element D, and the element D ′ is used as the raw material powder, nano-sized particles 125 and 129 are obtained. Regardless of the plasma generator such as direct current or alternating current, these nano-sized particles are composed of plasma as a constituent element, and become a gas along with cooling, and the constituent elements are uniformly mixed. By further cooling, nano-sized particles are formed from the gas via nano-sized droplets.

(7. Production of non-aqueous electrolyte secondary battery)
(7-1. Production of negative electrode for nonaqueous electrolyte secondary battery)
As the negative electrode, the negative electrode for a non-aqueous electrolyte secondary battery according to the present invention is used.

(7-2. Production of positive electrode for nonaqueous electrolyte secondary battery)
First, a positive electrode active material, a conductive additive, a binder, and a solvent are mixed to prepare a positive electrode active material composition. The composition of the positive electrode active material is directly applied on a metal current collector such as an aluminum foil and dried to prepare a positive electrode.

Any positive electrode active material can be used as long as it is generally used. For example, LiCoO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , LiNiO ₂ , LiCo _1/3 Ni _1/3 Mn _1/3. Compounds such as O ₂ and LiFePO ₄ .

  For example, carbon black is used as the conductive assistant, polyvinylidene fluoride (PVdF), a water-soluble acrylic binder is used as the binder, and N-methyl-2-pyrrolidone (NMP) is used as the solvent. Use water, etc. At this time, the contents of the positive electrode active material, the conductive additive, the binder, and the solvent are at levels that are normally used in non-aqueous electrolyte secondary batteries.

(7-3. Separator)
Any separator can be used as long as it has a function of insulating electronic conduction between the positive electrode and the negative electrode and is usually used in a non-aqueous electrolyte secondary battery. For example, a microporous polyolefin film, a porous aramid resin film, a porous ceramic, a nonwoven fabric, etc. can be used.

(7-4. Electrolytic solution / electrolyte)
Organic electrolyte (non-aqueous electrolyte), inorganic solid electrolyte, polymer solid electrolyte, etc. can be used for the electrolyte and electrolyte in non-aqueous electrolyte secondary batteries, Li polymer batteries, and the like.
Specific examples of the organic electrolyte solvent include carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate; diethyl ether, dibutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di Ethers such as butyl ether and diethylene glycol dimethyl ether; aprotic such as benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethylchlorobenzene, nitrobenzene Solvent, or two or more of these solvents Mixed solvent of thereof.

The electrolyte of the organic electrolyte includes LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAlO ₄ , LiAlCl ₄ , LiSbF ₆ , LiSCN, LiCl, LiCF ₃ SO ₃ , LiCF ₃ CO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) A mixture of one or more electrolytes made of a lithium salt such as ₂ can be used.

  As an additive for the organic electrolyte, it is desirable to add a compound capable of forming an effective solid electrolyte interface film on the surface of the negative electrode active material. For example, a substance having an unsaturated bond in the molecule and capable of reductive polymerization during charging, such as vinylene carbonate (VC), is added.

  Moreover, it can replace with said organic electrolyte solution and can use a solid-state lithium ion conductor. For example, a solid polymer electrolyte in which the lithium salt is mixed with a polymer made of polyethylene oxide, polypropylene oxide, polyethyleneimine, or the like, or a polymer gel electrolyte in which a polymer material is impregnated with an electrolytic solution and processed into a gel shape can be used.

Further, lithium nitride, lithium halide, lithium oxyacid _{salt, Li 4 SiO 4, Li 4} SiO 4 -LiI-LiOH, Li 3 PO 4 -Li 4 SiO 4, Li 2 SiS 3, Li 3 PO 4 -Li Inorganic materials such as ₂ S—SiS ₂ and phosphorus sulfide compounds may be used as the inorganic solid electrolyte.

(7-5. Assembly of non-aqueous electrolyte secondary battery)
A battery element is formed by disposing a separator between the positive electrode and the negative electrode as described above. After winding or stacking such battery elements into a cylindrical battery case or a rectangular battery case, an electrolytic solution is injected to obtain a nonaqueous electrolyte secondary battery.

  An example (cross-sectional view) of the nonaqueous electrolyte secondary battery of the present invention is shown in FIG. The non-aqueous electrolyte secondary battery 171 has a positive electrode 173 and a negative electrode 175 stacked in order of separator-positive electrode-separator-negative electrode via a separator 177, and wound so that the positive electrode 173 is on the inner side, Configure and insert it into the battery can 179. The positive electrode 173 is connected to the positive electrode terminal 183 via the positive electrode lead 181, and the negative electrode 175 is connected to the battery can 179 via the negative electrode lead 185. To be able to take out. Next, after filling the battery can 179 with the electrolyte 187 so as to cover the electrode plate group, the battery can 179 is formed with a circular lid plate and a positive electrode terminal 183 on the upper end (opening portion), and a safety valve mechanism is provided therein. A non-aqueous electrolyte secondary battery 171 according to the present invention can be manufactured by attaching a sealing body 189 having a built-in structure via an annular insulating gasket.

(7-6. Effect of Nonaqueous Electrolyte Secondary Battery According to the Present Invention)
The non-aqueous electrolyte secondary battery using the nano-sized particles according to the present invention as a negative electrode material has a conventional structure because the nano-sized particles according to the present invention have an element A having a higher unit volume and capacity per unit weight than carbon. The capacity is larger than that of the non-aqueous electrolyte secondary battery.

  In addition, as a binder for fixing the nano-sized particles as an active material layer on the current collector, a high-strength polyimide or the like is used, and the nano-sized particles are covered with each other. The binder is firmly bonded, and the current collector and the nano-sized particles are firmly adhered. Therefore, the nonaqueous electrolyte secondary battery according to the present invention has a long life.

Hereinafter, the present invention will be specifically described using examples and comparative examples.
[Example 1]
(Production of nano-sized particles)
A silicon powder and an iron powder are mixed at a molar ratio of Si: Fe = 23: 2, and the dried mixed powder is used as a raw material powder, using the apparatus of FIG. Silicon and iron nano-sized particles were prepared by continuously supplying a carrier gas into the plasma of H ₂ mixed gas.

More specifically, it was produced by the following method. After evacuating the reaction chamber with a vacuum pump, Ar gas was introduced to atmospheric pressure. This exhaustion and Ar gas introduction were repeated three times to exhaust the residual air in the reaction vessel. Thereafter, Ar—H ₂ mixed gas was introduced into the reaction vessel at a flow rate of 13 L / min, AC voltage was applied to the high frequency coil, and high frequency plasma was generated by a high frequency electromagnetic field (frequency 4 MHz). The plate power at this time was 20 kW. Ar gas having a flow rate of 1.0 L / min was used as a carrier gas for supplying the raw material powder. After the completion of the reaction, a gradual oxidation treatment was performed for 12 hours or more, and the obtained fine powder was collected with a filter.

(Evaluation of the composition of nano-sized particles)
Regarding the crystallinity of the nano-sized particles, XRD analysis was performed using RINT-Ultima III manufactured by Rigaku Corporation. FIG. 17 shows the XRD diffraction pattern of the nano-sized particles of Example 1. Example 1 was found to be composed of two components, Si and FeSi ₂ . It was also found that all Fe was present as silicide FeSi ₂ and there was almost no Fe as a single element (valence 0).

  Observation of the particle shape of the nano-sized particles was performed using a transmission electron microscope (TEM). 18 is a TEM image of nano-sized particles according to Example 1. FIG. Nano-sized particles in which hemispherical particles are bonded to the substantially spherical particles having a particle size of about 80 to 150 nm via the interface are observed, and the relatively dark colored portion in the same particles is iron containing iron. It is made of silicide, and a relatively light-colored portion is made of silicon. It can also be seen that an amorphous silicon oxide film having a thickness of 2 to 4 nm is formed on the surface of the nano-sized particles.

  Observation and composition analysis of nano-sized particles using a scanning transmission electron microscope (manufactured by JEOL, JEM 3100FEF), observation of particle shape by HAADF-STEM, and EDS (Energy Dispersive Spectroscopy: Energy Dispersive X) Line analysis). FIG. 19 (a) is a HAADF-STEM image of nano-sized particles, FIG. 19 (b) is an EDS map of silicon atoms at the same observation location, and FIG. 19 (c) is at the same observation location. It is an EDS map of an iron atom.

  According to FIG. 19A, nano-sized particles having a particle size of about 50 to 150 nm are observed, and each nano-sized particle has a substantially spherical shape. From FIG. 19 (b), it can be seen that silicon atoms are present in the entire nano-sized particles, and from FIG. 19 (c), many iron atoms are detected at the brightly observed positions in FIG. 19 (a). From the above, it can be seen that nano-sized particles have a structure in which a second phase formed of a compound of silicon and iron is bonded to a first phase formed of silicon.

(Preparation of negative electrode for non-aqueous electrolyte secondary battery)
(I) Preparation of Negative Electrode Slurry 64 parts by mass of nano-sized particles and 16 parts by mass of acetylene black (average particle size 35 nm, manufactured by Denki Kagaku Kogyo Co., Ltd., powdered product) were charged into a mixer. Further, a slurry was prepared by mixing polyimide (HCI-1000S, manufactured by Hitachi Chemical Co., Ltd.) as a binder at a ratio of 20 parts by mass in terms of solid content.
(Ii) Production of negative electrode Using the doctor blade of the automatic coating apparatus, the prepared slurry was 15 μm thick on a 10 μm thick electrolytic copper foil for current collector (Furukawa Electric Co., Ltd., NC-WS). After coating at 100 ° C. and drying at 100 ° C., after passing through a thickness adjustment step by press, a heat treatment step at 330 ° C. for 2 hours was performed to produce a negative electrode for a non-aqueous electrolyte secondary battery.

(Evaluation of cycle characteristics)
3 using a negative electrode for a non-aqueous electrolyte secondary battery, an electrolytic solution obtained by adding vinylene carbonate to a mixed solution of ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate containing 1.3 mol / L LiPF ₆ , and a metal Li foil counter electrode Three different lithium secondary batteries were constructed and the charge / discharge characteristics were examined. The evaluation of characteristics was performed by measuring the initial discharge capacity and the discharge capacity after 1 to 500 cycles of charge / discharge, and calculating the discharge capacity maintenance rate. The discharge capacity was calculated based on the total weight of silicide and active material Si effective for occlusion / release of lithium.

  In one cycle, charging was performed under constant current and constant voltage conditions until the current value was 0.1 C and the voltage value was 0.02 V in a 25 ° C. environment, and the charging was stopped when the current value decreased to 0.05 C. Next, discharging was performed under the condition of a current value of 0.1 C until the voltage with respect to the metal Li became 1.5 V, and a 0.1 C initial discharge capacity was measured. 1C is a current value that can be fully charged in one hour.

  In 2 to 30 cycles, in a 25 ° C environment, charging is performed under constant current and constant voltage conditions until the current value is 0.2 C and the voltage value is 0.02 V, and charging is stopped when the current value drops to 0.05 C. did. Next, discharge was performed under the condition of a current value of 0.2 C until the voltage with respect to the metal Li became 1.5V.

  In 31 cycles, in a 25 ° C. environment, charging was performed under constant current and constant voltage conditions until the current value was 0.2 C and the voltage value was 0.02 V, and the charging was stopped when the current value decreased to 0.05 C. Next, discharging was performed under the condition of a current value of 0.5 C until the voltage with respect to the metal Li became 1.5V.

  In 32 cycles, in a 25 ° C. environment, charging was performed under constant current and constant voltage conditions until the current value was 0.2 C and the voltage value was 0.02 V, and the charging was stopped when the current value decreased to 0.05 C. Next, discharge was performed under the condition of a current value of 1.0 C until the voltage with respect to the metal Li became 1.5V.

  In 33 cycles, charging was performed under constant current and constant voltage conditions until the current value was 0.2 C and the voltage value was 0.02 V in a 25 ° C. environment, and the charging was stopped when the current value decreased to 0.05 C. Next, discharging was performed under the condition of a current value of 2.0 C until the voltage against metal Li became 1.5 V.

  In 34 cycles, in a 25 ° C. environment, charging was performed under constant current and constant voltage conditions until the current value was 0.2 C and the voltage value was 0.02 V, and the charging was stopped when the current value decreased to 0.05 C. Next, discharging was performed under a condition of a current value of 5.0 C until the voltage with respect to the metal Li became 1.5V.

  In 35 to 500 cycles, charging was performed under a constant current and constant voltage condition up to a current value of 0.5 C and a voltage value of 0.02 V in a 25 ° C. environment, and the charging was stopped when the charging time reached 3 hours. . Next, discharging was performed under a condition of a current value of 5.0 C until the voltage with respect to the metal Li became 1.5V.

[Comparative Example 1]
64 parts by mass of nano-sized particles according to Example 1 and 16 parts by mass of acetylene black (average particle size 35 nm, manufactured by Denki Kagaku Kogyo Co., Ltd., powdered product) were charged into the mixer. Furthermore, styrene butadiene rubber (SBR) 40 wt% emulsion (manufactured by Nippon Zeon Co., Ltd., BM400B) as a binder, 5 parts by mass in terms of solid content, sodium carboxymethyl cellulose (Daicel Chemical) as a thickener to adjust the viscosity of the slurry The cycle characteristics were evaluated in the same manner as in Example 1 except that a slurry was prepared by mixing a 2 wt% solution (manufactured by Kogyo Co., Ltd., # 2200) at a ratio of 15 parts by mass in terms of solid content.

[Comparative Example 2]
The mixture was charged into a mixer at a ratio of 64 parts by mass of nano-sized pure silicon particles having an average particle diameter of 100 nm and 16 parts by mass of acetylene black (average particle 35 nm, Denki Kagaku Kogyo Co., Ltd., powdered product). Furthermore, the cycle characteristics were the same as in Example 1 except that a slurry was prepared by mixing polyimide (HCI-1000S, manufactured by Hitachi Chemical Co., Ltd.) as a binder at a ratio of 20 parts by mass in terms of solid content. Evaluation was performed.

  Table 1 summarizes the conditions of Example 1, Comparative Example 1, and Comparative Example 2.

The evaluation results of the cycle characteristics of Example 1, Comparative Example 1, and Comparative Example 2 are shown in FIG. In Example 1, a discharge capacity of 1000 mAh / g was maintained even after exceeding 500 cycles, and a sufficient capacity as a non-aqueous electrolyte secondary battery was maintained even by charge and discharge for several years as a battery of 500 cycles. ing. On the other hand, in Comparative Example 1, it can be seen that the cycle characteristics are worse than in Example 1. It can be seen that Comparative Example 2 also has poor cycle characteristics as compared to Example 1.
In Comparative Example 2 in which pure silicon particles having a particle size of 5 μm were used as the negative electrode active material, compared with the fact that the discharge capacity almost disappeared after 100 cycles, Comparative Example 1 was achieved by using nano-sized particles. It can be seen that the lifetime is sufficiently extended. In Example 1, it can be seen that the cycle characteristics are further improved.

  FIG. 21A shows an SEM photograph of the negative electrode according to Example 1, and FIG. 21B shows an SEM photograph of the negative electrode according to Comparative Example 1. In Comparative Example 1, since active material particles formed aggregates of about 100 μm in the slurry, large irregularities were formed on the surface of the applied active material layer. On the other hand, in Example 1, since the dispersibility of the nano-sized particles in the slurry was good, the surface of the applied active material layer was smooth.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

1, 1a ......... Negative electrode for non-aqueous electrolyte secondary battery 3 ......... Current collector 5, 5a ......... Active material layer 7 ......... Nano-sized particles 9 ......... Binder 10 ......... Conductive aid Agent 11 ......... Nano-sized particles 13 ......... First phase 15 ......... Second phase 17 ......... Nano-sized particles 18 ......... Nano-sized particles 19 ......... Third phase 21 ... …… Nano-sized particle 22 ......... Nano-sized particle 23 ......... Nano-sized particle 25 ......... Fourth phase 27 ......... Nano-sized particle 29 ......... Fifth phase 31 ......... Nano-sized particle manufacturing device 35 ......... Raw material powder supply port 37 ......... Raw material powder 39 ......... Sheath gas supply port 41 ......... Sheath gas 43 ......... Carrier gas 45 ......... Reaction chamber 47 ......... High frequency coil 49 ......... High frequency power source 51 ……… Plasma 53 ……… Filter 61 ……… Nano Izu Particles 63 ......... Sixth Phase 65 ......... Seventh Phase 67 ......... Nano-sized Particles 69 ......... Eighth Phase 71 ......... Nano-sized Particles 73 ......... Ninth Phase 75 ... …… Nano-sized particles 76 ……… Nano-sized particles 77 ……… Tenth phase 79 ……… Nano-sized particles 81 ……… Nano-sized particles 83 ……… Nano-sized particles 85 ……… Eleventh phase 87 ......... Nano-sized particles 89 ......... Twelfth phase 91 ......... Nano-sized particles 101 ......... Nano-sized particles 103 ......... Thirteenth phase 105 ......... Fourteenth phase 107 ......... Fifteenth Phase 109 ......... Nano-sized particles 110 ......... Nano-sized particles 111 ......... 16th phase 113 ......... Nano-sized particles 115 ......... 17th phase 117 ......... Nano-sized particles 119 ......... Nano-sized particles 121 ... 18th phase 1 3 ......... Nano-sized particles 125 ......... Nano-sized particles 127 ......... 19th phase 129 ......... Nano-sized particles 131 ......... 20th phase 171 ......... Non-aqueous electrolyte secondary battery 173 ... ... Positive electrode 175 ... ... Negative electrode 177 ... ... Separator 179 ... ... Battery can 181 ... ... Positive electrode lead 183 ... ... Positive electrode terminal 185 ... ... Negative electrode lead 187 ... ... Electrolyte 189 ... ... Sealing body 201 ... ... Negative electrode for non-aqueous electrolyte secondary battery 203 ......... Current collector 205 ......... Active material layer 207 ...... Active material particles 207a ......... Active material particles after charging 209 ......... Binder

Claims (24)

A negative electrode for a non-aqueous electrolyte secondary battery having an active material layer on a current collector,
The active material layer includes nano-sized particles containing the element A and the element D, and a binder,
The element A is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In and Zn;
The element D is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, a lanthanoid element (excluding Pm), Hf, At least one element selected from the group consisting of Ta, W, Re, Os, Ir,
The nano-sized particles have at least a first phase that is a single element or a solid solution of the element A, and a second phase that is a compound of the element A and the element D,
The first phase and the second phase are bonded via an interface;
The first phase and the second phase are exposed on the outer surface of the nano-sized particles;
The first phase has a substantially spherical surface other than the interface,
At least a part of the surface of the nano-sized particles is covered with the binder,
The negative electrode for a non-aqueous electrolyte secondary battery, wherein the binder is at least one selected from the group consisting of polyimide, polyamideimide, polybenzimidazole, and polyamide. The element A is Si;
The element D is selected from the group consisting of Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Ru, Rh, Ba, Hf, Ta, W, and Ir. The negative electrode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode is at least one element selected. 3. The negative electrode for a non-aqueous electrolyte secondary battery according to claim 1, wherein the second phase of the nano-sized particles is a compound of DA _x (1 <x ≦ 3). Furthermore, the nano-sized particles have a third phase that is a compound of the element A and the element D,
The said 3rd phase is disperse | distributing in the said 1st phase, The negative electrode for nonaqueous electrolyte secondary batteries of any one of Claims 1-3 characterized by the above-mentioned.   5. The method according to claim 1, wherein the first phase is mainly crystalline silicon, and the second phase and / or the third phase is crystalline silicide. The negative electrode for nonaqueous electrolyte secondary batteries as described. The nano-sized particles are Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), An element D ′ that is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir;
The element D ′ is an element of a different type from the element D constituting the second phase,
The nano-sized particles further include a fourth phase that is a compound of the element A and the element D ′,
The first phase and the fourth phase are bonded via an interface;
The negative electrode for a nonaqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the fourth phase is exposed on an outer surface of the nano-sized particles. A negative electrode for a non-aqueous electrolyte secondary battery having an active material layer on a current collector,
The active material layer includes nano-sized particles containing the element A and the element M, and a binder.
The element A is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In and Zn;
The element M is at least one element selected from the group consisting of Cu, Ag and Au;
The nano-sized particles have a sixth phase that is a single element or a solid solution of the element A, and a seventh phase that is a compound of the element A and the element M or a single element or a solid solution of the element M,
The sixth phase and the seventh phase are bonded via an interface,
Both the sixth phase and the seventh phase are exposed on the outer surface of the nano-sized particles;
The sixth phase and the seventh phase have a substantially spherical surface other than the interface,
At least a part of the surface of the nano-sized particles is covered with the binder,
The negative electrode for a non-aqueous electrolyte secondary battery, wherein the binder is at least one selected from the group consisting of polyimide, polyamideimide, polybenzimidazole, and polyamide. The negative electrode for a nonaqueous electrolyte secondary battery according to claim 7, wherein the seventh phase is a compound of MA _x (x ≦ 1, 3 <x). The nano-sized particles further include at least one element M ′ selected from the group consisting of Cu, Ag, and Au,
The element M ′ is a different element from the element M constituting the seventh phase,
The nano-sized particles further have an eighth phase that is a compound of the element A and the element M ′ or a simple substance or a solid solution of the element M ′.
The sixth phase and the eighth phase are bonded via an interface,
The eighth phase is exposed on the outer surface of the nano-sized particles;
The negative electrode for a nonaqueous electrolyte secondary battery according to claim 7 or 8, wherein the eighth phase has a spherical surface other than the interface. The nano-sized particles are Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), An element D that is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir;
The nano-sized particles further have a ninth phase that is a compound of the element A and the element D,
The sixth phase and the ninth phase are joined via an interface;
The negative electrode for a nonaqueous electrolyte secondary battery according to any one of claims 7 to 9, wherein the ninth phase is exposed on an outer surface of the nano-sized particles. The nano-sized particles further include a tenth phase that is a compound of the element A and the element D,
The negative electrode for a nonaqueous electrolyte secondary battery according to any one of claims 7 to 10, wherein a part or all of the tenth phase is covered with the sixth phase. . The nano-sized particles are Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), An element D ′ that is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir;
The element D ′ is an element of a different type from the element D constituting the ninth phase,
The nano-sized particles further include an eleventh phase that is a compound of the element A and the element D ′,
The sixth phase and the eleventh phase are bonded via an interface;
11. The negative electrode for a nonaqueous electrolyte secondary battery according to claim 10, wherein the eleventh phase is exposed on an outer surface of the nano-sized particles. The nano-sized particles further have a twelfth phase that is a compound of the element A and the element D ′,
13. The negative electrode for a nonaqueous electrolyte secondary battery according to claim 12, wherein a part or all of the twelfth phase is covered with the sixth phase. A negative electrode for a non-aqueous electrolyte secondary battery having an active material layer on a current collector,
The active material layer includes nano-sized particles containing the element A-1, the element A-2, and the element D, and a binder,
The element A-1 and the element A-2 are two kinds of elements selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In and Zn,
Element D is Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, a lanthanoid element (except Pm), Hf, At least one element selected from the group consisting of Ta, W, Re, Os, Ir,
The nano-sized particles include a thirteenth phase that is a single element or a solid solution of the element A-1, a fourteenth phase that is a single element or a solid solution of the element A-2, the element A-1 and the element D, And a fifteenth phase that is a compound of
The thirteenth phase and the fourteenth phase are joined via an interface;
The thirteenth phase and the fifteenth phase are joined via an interface;
The thirteenth phase and the fourteenth phase have a substantially spherical surface other than the interface,
The thirteenth phase, the fourteenth phase, and the fifteenth phase are exposed on the outer surface of the nano-sized particles;
At least a part of the surface of the nano-sized particles is covered with the binder,
The negative electrode for a non-aqueous electrolyte secondary battery, wherein the binder is at least one selected from the group consisting of polyimide, polyamideimide, polybenzimidazole, and polyamide. The element A-1 and the element A-2 are two kinds of elements selected from the group consisting of Si, Sn, and Al.
The element D is one kind selected from the group consisting of Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh and Ba. The negative electrode for a nonaqueous electrolyte secondary battery according to claim 14, wherein the negative electrode is an element. The nano-sized particles further include a sixteenth phase that is a compound of the element A-1 and the element D;
16. The negative electrode for a nonaqueous electrolyte secondary battery according to claim 14, wherein a part or all of the sixteenth phase is covered with the thirteenth phase. A seventeenth phase that is a compound of the element A-1 and the element D;
The seventeenth phase is bonded to the fourteenth phase through an interface and exposed to the outer surface of the nano-sized particles. The negative electrode for nonaqueous electrolyte secondary batteries as described. One or more of the fifteenth phase, the sixteenth phase, and the seventeenth phase are compounds of D (A-1) _y (1 <y ≦ 3). The negative electrode for a nonaqueous electrolyte secondary battery according to any one of claims 14 to 17. The nano-sized particles further include an element A-3 that is one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn,
The element A-3 is a different kind of element from the element A-1 and the element A-2,
The nano-sized particles have an eighteenth phase that is a simple substance or a solid solution of the element A-3,
The thirteenth phase and the eighteenth phase are joined via an interface;
The eighteenth phase has a substantially spherical surface other than the interface,
The negative electrode for a non-aqueous electrolyte secondary battery according to claim 14, wherein the eighteenth phase is exposed on an outer surface of the nano-sized particles. The nano-sized particles are Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanoid elements (excluding Pm), An element D ′ that is at least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir;
The element D ′ is an element of a different type from the element D constituting the fifteenth phase,
The nano-sized particles further include a nineteenth phase that is a compound of the element A-1 and the element D ′,
The thirteenth phase and the nineteenth phase are bonded via an interface;
The negative electrode for a non-aqueous electrolyte secondary battery according to claim 14, wherein the nineteenth phase is exposed on an outer surface of the nano-sized particles. The nano-sized particles further include a twentieth phase that is a compound of the element A-1 and the element D ′,
21. The negative electrode for a nonaqueous electrolyte secondary battery according to claim 20, wherein a part or all of the twentieth phase is covered with the thirteenth phase.   The average particle size of the nano-sized particles is 2 to 500 nm, The negative electrode for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 21.   The non-aqueous electrolyte according to any one of claims 1 to 22, wherein the active material layer contains at least one of carbon black, carbon nanotube, and carbon fiber as a conductive additive. Negative electrode for secondary battery. A positive electrode capable of inserting and extracting lithium ions;
A negative electrode according to any one of claims 1 to 23;
Having a separator disposed between the positive electrode and the negative electrode;
A nonaqueous electrolyte secondary battery in which the positive electrode, the negative electrode, and the separator are provided in an electrolyte having lithium ion conductivity.