TW201343549A - Porous silicon particles and porous silicon-composite particles - Google Patents

Abstract

The present invention addresses the problem of obtaining porous silicon particles and porous silicon-composite particles that are suitable for use, for example, in a negative-electrode material for a lithium-ion battery that has high capacity and good cycle characteristics. In order to solve said problem, the present invention uses porous silicon particles (1), each of which comprises a plurality of silicon microparticles (3) joined together with a contiguous void and is characterized in that: the mean (x) of the particle diameters or rod diameters of said silicon microparticles is between 2 nm and 2 μm, inclusive; the standard deviation (sigma) of the particle diameters or rod diameters of the silicon microparticles is between 1 and 500 nm, inclusive; and the quotient (σ/x) of said standard deviation σ and mean (x) is between 0.01 and 0.5, inclusive. Alternatively, porous silicon-composite particles, each of which comprises a plurality of silicon microparticles and a plurality of silicon-compound particles joined together with a contiguous void and is characterized by having characteristics similar to the above, may also be used.

Description

Porous cerium particles and porous cerium composite particles Technical field

The present invention relates to a porous ruthenium particle used for a negative electrode or the like for a lithium ion battery. The porous tantalum particles of the present invention can be used for capacitors, lithium ion capacitors, and tantalum semiconductors for solar cells.

Background technique

Conventionally, lithium ion batteries using various carbon-based materials such as natural graphite, artificial graphite, amorphous carbon, and mesocarbon carbon, lithium titanate, or tin alloy as negative electrode active materials have been put into practical use. Further, a conductive agent such as a negative electrode active material or carbon black and a binder of a resin are blended, and a slurry is prepared, coated on a copper foil, dried, and a negative electrode is formed.

On the other hand, in order to increase the capacity, a lithium compound has been developed using a metal or an alloy having a large theoretical capacity, and in particular, a negative electrode for a lithium ion battery using ruthenium and an alloy thereof as a negative electrode active material. However, since the lithium ion is adsorbed and the volume is expanded by about 4 times with respect to the enthalpy before the adsorption, the negative electrode using ruthenium as the negative electrode active material re-expands and contracts during the charge and discharge cycle. Therefore, there is a problem in that the negative electrode active material is peeled off or the like, and the life is extremely short as compared with the negative electrode composed of a conventional carbon-based active material.

As a conventional manufacturing method using a negative electrode of ruthenium, A technique of pulverizing to a size of several micrometers and applying it to a conductive material to form a negative electrode material for a lithium battery (for example, refer to Patent Document 1) is known.

In addition, a conventional method for producing a negative electrode using ruthenium includes a method of anodicizing a ruthenium substrate and forming a groove such as a slit, and a method of crystallizing fine ruthenium in a strip-shaped metal (for example, refer to Patent Document 2) Wait.

Further, polymer particles such as polystyrene or PMMA are deposited on the conductive substrate, and a metal which is alloyed with lithium is applied to the polymer particles by gold plating, and then a porous body of metal is removed by removing the polymer particles (porous The technique of the plastid (for example, refer to Patent Document 3) is also known.

Further, a technique of using a Si intermediate alloy corresponding to the intermediate program of the present invention as a negative electrode material for a lithium battery (for example, refer to Patent Documents 4 and 5) is known.

Moreover, it is known to heat-treat it as a negative electrode material for lithium batteries (for example, refer patent document 6).

Further, in connection with this technique, a technique of completely removing the element M by acid or alkali by a Si alloy of Si and element M which is produced by a rapid solidification technique is known (for example, refer to Patent Document 7).

Further, a technique of etching a metal ruthenium or a ruthenium alloy by hydrofluoric acid or nitric acid (for example, refer to Patent Documents 8, 9, 10) is also known.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent No. 4172443

Patent Document 2: Japanese Laid-Open Patent Publication No. 2008-135364

Patent Document 3: Japanese Laid-Open Patent Publication No. 2006-260886

Patent Document 4: Japanese Laid-Open Patent Publication No. 2000-149937

Patent Document 5: Japanese Patent Laid-Open Publication No. 2004-362895

Patent Document 6: JP-A-2009-032644

Patent Document 7: Japanese Patent No. 3876642

Patent Document 8: US Patent Application Publication No. 2006/0251561

Patent Document 9: US Patent Application Publication No. 2009/0186267

Patent Document 10: US Patent Application Publication No. 2012/0129049

Summary of invention

However, the technique of Patent Document 1 uses a single crystal of several micrometers size obtained by pulverizing a single crystal ruthenium, and a plate or powder having a layered or three-dimensional network structure as a negative electrode active material. Further, in order to impart conductivity, a ruthenium compound (from ruthenium carbide, ruthenium cyanide, ruthenium nitride, ruthenium oxide, osmium boride, lanthanum borohydride, lanthanum borohydride, lanthanum oxynitride, ruthenium alkali metal) is used. One or more of the ruthenium compound group composed of an alloy, a bismuth base metal alloy, or a ruthenium transition metal alloy. However, in the case of charge and discharge, the negative electrode active material described in Patent Document 1 generates micronization of the negative electrode active material, peeling of the negative electrode active material, occurrence of negative electrode cracking, and negative electrode activity. The conductivity between the substances is lowered, and the capacity is lowered. Therefore, there is a problem that the cycle characteristics are poor and the life of the secondary battery is short. In particular, it is expected that the volume change during charging and discharging of the negative electrode material is large, and therefore there is a problem that cracking easily occurs and the charge and discharge cycle characteristics are not good.

Further, in the technique of Patent Document 2, a slurry of a negative electrode active material, a conductive auxiliary agent, and a binder is applied and dried, and a negative electrode is formed. As described above, the negative electrode is adhered to the negative electrode active material and the current collector by an adhesive having low conductivity, and the amount of the resin used must be kept to a minimum so that the internal resistance does not become large and the bonding strength is weak. In the technique of Patent Document 2, when the negative electrode active material is charged and discharged, the micronization of the negative electrode active material and the peeling of the negative electrode active material, the occurrence of the negative electrode crack, and the negative electrode active material occur. The conductivity is lowered and the capacity is lowered. Therefore, there is a problem that the cycle characteristics are poor and the life of the secondary battery is short.

Further, in the technique of Patent Document 3, polymer particles such as polystyrene or PMMA are deposited on a conductive substrate, and after the metal is alloyed with lithium by gold plating on the polymer particles, the polymer particles can be removed. A porous body (porous body) of metal is produced. However, in the production of a porous body of Si, it is extremely difficult to apply Si to polymer particles such as styrene or PMMA, and it is not industrially applicable.

Further, the technique of Patent Document 4 is characterized in that the melt of the raw material constituting the alloy particles is cooled and solidified so as to have a solidification rate of 100 ° C /sec or more to form Si-containing particles and at least partially surround them. A method of producing an anode material for a non-aqueous electrolyte secondary battery by a step of alloying a phase of a solid solution or an intermetallic compound. However, in this method, in terms of Li reaction, diffusion must be carried out through the inclusion of the Si-containing solid solution and lacking The reactivity is further inconvenient in terms of a small amount of Si which contributes to charge and discharge.

In addition, the technique of the patent document 5 is comprised by the bismuth alloy powder containing the metal element of the 1 or 2 or more types of copper, nickel, and cobalt. Since the niobium alloy powder is synthesized by a single roll method or a spray method, it is possible to suppress micronization depending on the volume change of adsorption or release of lithium ions or the like. However, in this method, in terms of the Li reaction, it is necessary to diffusely move through the Si-containing solid solution and lack reactivity, and in view of the fact that the Si content which contributes to charge and discharge is small, it is not practical.

Further, the technique of Patent Document 6 includes quenching containing Si and selected from the group consisting of Co, Ni, Ag, Sn, Al, Fe, Zr, Cr, Cu, P, Bi, V, Mn, Nb, Mo, In, and rare earth elements. a step of obtaining a Si-based amorphous alloy by a molten alloy of one or more elements, and a step of heat-treating the Si-based amorphous alloy. The Si-based amorphous alloy obtained by the heat treatment precipitates a fine crystal Si core of about several tens of nanometers to about 300 nm. However, in this method, in terms of the Li reaction, it is necessary to diffusely move through the Si-containing solid solution and lack reactivity, and in view of the fact that the Si content which contributes to charge and discharge is small, it is not practical.

Further, the technique of Patent Document 7 is adapted to produce an amorphous ribbon or a fine powder, and the cooling rate is all set at 10 ⁴ K/sec or more to solidify. In the solidification of a general alloy, dendritic crystals in which the dendrites grow once and twice, and the dendrites grow. In a special alloy system (Cu-Mg system, Ni-Ti system, etc.), an amorphous metal can be formed at 10 ⁴ K/sec or more, but in other systems (for example, Si-Ni system), even if the cooling rate is all more than 10 ⁴ K / sec was solidified amorphous metal also can not be obtained, and the formation of crystalline phases. The crystal size at which the crystal phase is formed depends on the relationship between the cooling rate (R: K/sec) and the dendritic arm spacing (DAS: μm).

DAS=A×R ^B (generally, A: 40 to 100, B: -0.3 to -0.4)

Therefore, when having a crystal phase, for example, A: 60, B: -0.35, D is 1 μm at R: 10 ⁴ K/sec. The crystal phase also depends on the size, so that a fine crystal phase of 10 nm or the like cannot be obtained. For these reasons, it is known that a material such as Si-Ni is not able to obtain a porous material composed of a fine crystal phase by the rapid solidification technique alone.

Further, in the techniques of Patent Documents 8 and 9, the metal crucible is etched using hydrofluoric acid or nitric acid to form fine pores on the surface. However, when the BET specific surface area is from 140 to 400 m ² /g, there is a problem that the Si negative electrode active material is insufficient from the viewpoint of charge and discharge responsiveness. Further, the voids formed by the etching are non-uniformly dispersed, and the pores are non-uniformly present from the surface to the center of the particles. Therefore, there is a problem that the volume expansion and contraction at the time of charge and discharge increases the micronization inside the particles and the life is short.

Further, in the technique of Patent Document 10, after the molten alloy (cerium-containing amorphous alloy) is rapidly solidified, it is etched using hydrofluoric acid or nitric acid to recover ruthenium particles. This preferentially crystallizes the ruthenium particles upon solidification by using the eutectic composition, and by increasing the cooling rate (100 K/s), a fine granular or plate-like primary crystal ruthenium can be formed in the alloy. Further, when an Al-Si eutectic structure is left between the dendrites during crystal growth, voids (pores) may be formed in the subsequent etching treatment. However, the rapid solidification and the mechanism cannot be made to have a continuous continuity. The spongy shape of the structure.

The present invention has been made in view of the above problems, and an object thereof is to obtain porous tantalum particles suitable for a negative electrode material for a lithium ion battery having high capacity and good cycle characteristics.

In order to achieve the above object, the present inventors have intensively reviewed and found that a fine porous material can be obtained by phase separation of a bismuth alloy (precipitation from ruthenium in a ruthenium alloy) and dealloying. Since the precipitation of the ruthenium from the ruthenium alloy is carried out in the molten metal at a high temperature, the distribution of the primary particle diameter is less likely to occur in the surface layer portion and the inside of the porous ruthenium particles obtained by the deal component removal. This is the diffusion of molten metal as a solvent, and when the removal atom in the ruthenium alloy is substituted with a solvent atom, it is directly discharged from the diffusion interface by convection in the solvent, and the molten metal of a predetermined composition often exists at the diffusion interface, so that a certain concentration exists. gradient. Therefore, the diffusion in the niobium alloy is carried out at a constant speed, so that helium atoms which contribute to the phase separation can be supplied at a constant speed, and therefore the size of the niobium microparticles is constant.

Further, the porous fine particles obtained by the above-described production method are less likely to have a distribution having a large void ratio. On the other hand, for example, in the etching by acid, since the concentration of the concentration of the de-component element is limited inside the particles, the porosity of the surface layer portion of the particle is large, and the porosity of the inside of the particle is small. Depending on the conditions, a Si core having no pores is left in the center of the particle, and when it reacts with Li, micronization occurs, and cycle characteristics are deteriorated. The present invention is based on this knowledge.

That is, the following invention is provided.

(1) A porous cerium particle in which a plurality of cerium microparticles are joined to each other and has a continuous void, wherein the strontium microparticles have a spherical or polygonal columnar shape, and the particle diameter of the cerium microparticles, the pillar diameter or the pillar side The average x is 2 nm to 2 μm, and the particle diameter, the pillar diameter or the standard deviation σ of the pillar side is 1 to 500 nm, and the ratio (σ/x) of the average x to the standard deviation σ is 0.01 to 0.5. .

(2) The porous tantalum particle according to (1), wherein the shape of the fine particles is a flat spherical shape, a cylindrical shape or a polygonal column shape, and an average longest diameter or a longest side a and an average shortest or shortest side The ratio b (a/b) is 1.1 to 50.

(3) The porous tantalum particle according to (1), wherein the porous niobium particles have an average particle diameter of 0.1 μm to 1000 μm, and the porous niobium particles have an average void ratio of 15 to 93%; The average particle diameter Ds of the cerium fine particles in the vicinity of the surface of the porous cerium particle in the radial direction of 50% or more, and the cerium fine particle in the internal region of the particle within 50% of the porous cerium particle in the radial direction The ratio of the average particle diameter Di to Ds/Di is 0.5 to 1.5, and the porosity Xs of the region near the surface of the porous cerium particle in the radial direction of 50% or more and the radial enthalpy particle are 50 in the radial direction. The ratio of the void ratio Xi of the inner region of the particles within the range of X is 0.5 to 1.5, and the ratio of the elements other than oxygen is 矽80 atom% or more.

(4) The porous tantalum particle according to the above aspect, wherein the porous tantalum particle is divided into a region S near the surface in the radial direction of 90% or more, and an inner region I of the particle having a radius of 90% or less. And constituting the aforementioned surface The average particle diameter of the above-mentioned fine particles in the vicinity S is Es, and when the average particle diameter of the above-mentioned fine particles constituting the internal region I of the particles is Ei, Es/Ei is 0.01 to 1.0.

(5) The porous cerium particles according to the above aspect, characterized in that the cerium microparticles are characterized by containing 原子80 atom% or more of solid cerium microparticles in a ratio of elements other than oxygen.

(6) The porous tantalum particle according to (1), wherein the area of the joint between the fine particles is 30% or less of the surface area of the fine particles.

(7) The porous tantalum particle according to (1), wherein the joint portion of the tantalum fine particles and the adjacent fine particles is larger in thickness or diameter than the adjacent fine particles. The microparticle diameter is 80% or less, and the joint portion is composed of a crystalline niobium or tantalum oxide.

(8) The porous tantalum particles according to (2), wherein the plurality of the fine particles are oriented, and the long axis directions of the plurality of fine particles are within ±30° in a certain direction.

(9) A porous ruthenium composite particle obtained by bonding a plurality of ruthenium microparticles to a plurality of ruthenium compound particles and having continuous voids, wherein the ruthenium compound particles comprise ruthenium and are selected from the group consisting of As, Ba, Ca, and Ce. , Co, Cr, Cu, Er, Fe, Gd, Hf, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, Pr, Pt, Pu, Re, Rh, Ru, Sc, Sm, Sr, Ta a compound of one or more complex elements in a group consisting of Te, Th, Ti, Tm, U, V, W, Y, Yb, and Zr; and the average particle size, pillar diameter, or strut edge of the above-mentioned fine particles x is 2 nm to 2 μm, the particle size of the aforementioned fine particles, The standard deviation σ of the pillar diameter or the pillar edge is 1 to 500 nm, and the ratio (σ/x) of the aforementioned average x to the aforementioned standard deviation σ is 0.01 to 0.5.

(10) The porous composite ruthenium particle according to (9), wherein the ruthenium microparticle has a shape of a flat spherical shape, a columnar shape or a polygonal column shape, and an average longest diameter or a longest side a and an average shortest diameter or The ratio of the shortest side b (a/b) is 1.1 to 50.

(11) The porous composite ruthenium particles according to the above aspect, wherein the porous ruthenium composite particles have an average particle diameter of from 0.1 μm to 1000 μm.

(12) The porous composite cerium particles according to the above aspect, wherein the cerium fine particles are solid cerium fine particles containing 矽80 atom% or more in terms of a ratio of elements other than oxygen.

(13) The porous composite ruthenium particle according to the above aspect, wherein the ruthenium compound particles have an average particle diameter of 50 nm to 50 μm, and the ruthenium compound particles are 50 in a ratio of elements other than oxygen. Up to 90 atomic percent of solid bismuth compound particles.

The porous composite ruthenium particle according to the above aspect, wherein the average particle diameter Ds of the ruthenium microparticles in the vicinity of the surface of the porous ruthenium composite particle in the radial direction of 50% or more is The ratio Ds/Di of the average particle diameter Di of the cerium fine particles in the inner region of the particles within 50% of the radius of the porous cerium composite particles is 0.5 to 1.5.

The porous composite ruthenium particle according to the above aspect, wherein the porous ruthenium composite particle has a porosity Xs in a region near the surface of 50% or more in the radial direction, and is composited with the porous ruthenium. The ratio of the void ratio Xi of the internal region of the particle within 50% of the radial direction of the bulk particle Xs/Xi 0.5 to 1.5.

(16) The porous composite ruthenium particle according to the above aspect, wherein the porous ruthenium complex particles are divided into a region S near the surface in the radial direction of 90% or more and 90% or less in the radial direction. In the internal region I of the particle, and the average particle diameter of the ruthenium microparticles constituting the region S near the surface is Es, and the average particle diameter of the ruthenium microparticles constituting the inner region I of the particle is Ei, Es/Ei is 0.01 to 1.0.

(17) The porous composite ruthenium particle according to the above aspect, wherein the joint portion of the ruthenium fine particles and the adjacent ruthenium fine particles is larger in thickness or diameter than the adjacent ruthenium fine particles The 矽 fine particle diameter is 80% or less, and the joint portion is composed of a crystalline ruthenium or osmium oxide.

(18) The porous composite ruthenium particle according to (10), wherein a plurality of the ruthenium microparticles are oriented, and a majority of the ruthenium microparticles have a major axis direction within ±30° of a certain direction.

According to the present invention, porous ruthenium particles such as a negative electrode material for a lithium ion battery which is suitable for achieving high capacity and good cycle characteristics can be obtained.

1‧‧‧Porous porous particles

3‧‧‧矽Microparticles

7‧‧‧矽Internal alloy

9‧‧‧2nd phase

11‧‧‧Single roll casting machine

13‧‧‧矽 alloy

15‧‧‧坩埚

17‧‧‧Steel rolls

19‧‧‧Striped niobium alloy

21‧‧‧melting device; melt impregnation device

23‧‧‧ melt

25‧‧‧guide roller

27‧‧‧Support roll

31‧‧‧ gas spray device

33‧‧‧坩埚

35‧‧‧Nozzles

36‧‧‧Spray gas

37‧‧‧ gas jet

38‧‧‧jet stream

39‧‧‧Powdered tantalum alloy

41‧‧‧Rotating disc spray device

43‧‧‧坩埚

45‧‧‧Nozzles

49‧‧‧ rotating disc

51‧‧‧ powdered niobium intermediate alloy

53‧‧‧坩埚

55‧‧‧Molding

57‧‧‧Block-like tantalum alloy

61‧‧‧Melt impregnation device

63‧‧‧Grained niobium alloy

65‧‧‧Immersion cage

67‧‧‧Pressure cylinder

69‧‧‧ melt

71‧‧‧Melt impregnation device

73‧‧‧Grained niobium alloy

75‧‧‧Immersion cage

79‧‧‧ melt

81‧‧‧Mechanical mixer

83‧‧‧ gas blown plug

93‧‧‧Grained niobium alloy

101‧‧‧Porous 矽 composite particles

103‧‧‧矽Microparticles

105‧‧‧矽 compound particles

107‧‧‧矽Internal alloy

109‧‧‧2nd phase

111‧‧‧矽Internal alloy

I‧‧‧particle interior area

S‧‧‧ Area near the surface

Fig. 1(a) is a view showing the porous tantalum particle 1 of the present invention, and Fig. 1(b) is a view showing a region S near the surface of the porous tantalum particle 1 and an inner region I of the particle.

2(a) to 2(c) are diagrams showing the outline of a method for producing the porous tantalum particles 1.

Fig. 3 is a view showing the outline of a method for producing a belt-shaped tantalum intermediate alloy of the present invention.

Fig. 4 is a view for explaining the steps of impregnating a molten tantalum alloy into a molten element of the present invention.

Fig. 5(a) is a view showing the gas atomizing device 31 of the present invention, and Fig. 5(b) is a view showing the rotating disk spraying device 41 of the present invention.

6(a) to (c) are views for explaining the steps of manufacturing the bulk tantalum intermediate alloy.

7(a) and 7(b) are views showing the melt immersion apparatus of the present invention.

Fig. 8(a) is a view showing the porous tantalum composite particle 101 of the present invention, and Fig. 8(b) is a view showing a region S near the surface of the porous tantalum composite particle 101 of the present invention and an internal region I of the particle.

9(a) to 9(c) are schematic views showing a first manufacturing method of the porous tantalum composite particles 101.

10(a) to 10(c) are schematic views showing a second method of manufacturing the porous tantalum composite particles 101.

Figure 11 is a SEM photograph of the inside of the porous ruthenium particles of Examples 1-12.

Fig. 12 is a SEM photograph of porous cerium particles of Comparative Example 1-1.

Figure 13 is an X-ray diffraction grating image of the inside of the porous ruthenium particles of Examples 1-12.

Fig. 14 is a SEM photograph of the surface of the porous ruthenium complex particles of Example 2-1.

Fig. 15 is a SEM photograph of the internal cross section of the porous ruthenium composite particles of Example 2-1.

Figure 16 is an SEM photograph of the surface of the porous tantalum composite particle of Example 2-1. sheet.

Fig. 17 is an X-ray diffraction grating image of the fine particles of the porous tantalum composite particles of Example 2-1.

Figure 18 is a SEM photograph of porous cerium particles of Example 3-7.

Fig. 19 is a TEM photograph of ruthenium fine particles constituting the porous ruthenium particles of Example 3-7.

Figure 20 is a particle size distribution of the fine particles of the porous tantalum particles of Examples 3-7.

Fig. 21 is a TEM photograph of ruthenium microparticles constituting the porous ruthenium particles of Example 3-8, and restricts the electron beam diffraction image of the field of view (top left).

Fig. 22 is a SEM photograph showing a cross section of the fine particles and the second phase after the immersion to the molten metal in the step (b) of the embodiment 1-15.

Fig. 23 is a SEM photograph showing the fine particles of the surface of the porous tantalum particles after the second phase is removed after the step (c) of the embodiment 2-15.

Fig. 24 is a SEM photograph of the surface of the porous cerium particles of Comparative Example 2-4.

Figure 25 is a SEM photograph of porous cerium particles of Example 3-1.

Figure 26 is a SEM photograph of the porous ruthenium particles of Example 3-2.

Figure 27 is a SEM photograph of the porous ruthenium particles of Example 3-3.

Fig. 28 (a) is a photograph of the microstructure of the intermediate alloy of Examples 1 to 15, and (b) is an enlarged view thereof.

Form for implementing the invention [Porous ruthenium particles] (Composition of porous ruthenium particles)

Hereinafter, the porous tantalum particle 1 of the present invention will be described with reference to Fig. 1 . The porous tantalum particles 1 are porous tantalum particles having a plurality of fine particles 3 joined to each other and having continuous voids. Further, the shape of the fine particles 3 is preferably spherical, cylindrical or polygonal, and the particle diameter of the fine particles 3 and the diameter of the pillars are small. Or the average x of the pillar side is 2 nm to 2 μm, and the particle diameter of the 矽 microparticle 3, the standard deviation of the pillar diameter or the pillar side σ is 1 to 500 nm, and the ratio of the average x to the standard deviation σ (σ/x) is 0.01. To 0.5. Since the ratio of the average x to the standard deviation σ (i.e., the coefficient of variation) is within a predetermined range, the size of the fine particles 3 is uniform.

The shape of the fine particles 3 has a flat spherical shape, a cylindrical shape or a polygonal column shape, and the ratio of the average longest diameter or the longest side a of the fine particles 3 to the average shortest diameter or the shortest side b (a/b) is 1.1 to 50. Since the ruthenium microparticles 3 have a suitably flat shape, when the porous ruthenium particles 1 are used for a negative electrode active material of a lithium ion secondary battery, when the ruthenium microparticles 3 are expanded and contracted during charge and discharge, they expand so as to fill the voids. It has the effect of not easily causing cracking at the negative electrode. Further, when it is less than 1.1, it is easy to cause cracking in the negative electrode due to the isotropic expansion and contraction. Moreover, when it is larger than 50, for example, when it grows into a fiber shape, it will become easy to generate|occur|produce the fracture of a negative electrode by the expansion-contraction in one direction.

Further, the porous tantalum particles 1 have a three-dimensional network structure having continuous voids, and the fine particles 3 are joined, and the average particle diameter is 0.1 μm to 1000 μm, and the average void ratio is 15 to 93%. In addition, the porous tantalum particles 1 are characterized by containing 原子80 atom% or more in proportion to elements other than oxygen, and the remaining solid particles containing an intermediate alloy element, a molten element, and other unavoidable impurities described later.

Further, even on the surface of the porous tantalum particles There is also no characteristic problem with the oxide layer below 20 nm.

Further, the oxide layer (oxide film) on the surface of the porous tantalum particles can be formed by removing the second phase with hydrochloric acid or the like and then immersing it in nitric acid of 0.0001 to 0.1 N. Alternatively, the second phase may be removed by distillation under reduced pressure, and then formed under an oxygen partial pressure of 0.00000001 to 0.02 MPa.

Further, as shown in Fig. 1(b), the porous tantalum particles 1 are divided into a region S near the surface in the radial direction of 50% or more and a region I inside the particle having a radius of 50% or less, and the porous germanium particles are formed. When the average particle diameter of the fine particles in the vicinity of the surface is Ds, and the average particle diameter of the fine particles of the inner region of the particles constituting the porous tantalum particles is Di, Ds/Di is 0.5 to 1.5.

Further, the crystal grains of the intermediate alloy (Fig. 28) are subjected to the de-component etching and the change in the step (c) of the impregnation of the molten element in the step (b) described later, and the size corresponding to the crystal grains of the intermediate alloy is obtained. Porous cerium particles (not pulverized by micro pulverization). The porous tantalum particles are divided into a region S near the surface in the radial direction of 90% or more and an inner region I of the particles in the radial direction of 90% or less, and the average particle diameter of the fine particles of the vicinity of the surface constituting the porous tantalum particle is Es, and when the average particle diameter of the fine particles of the inner region of the particles constituting the porous tantalum particles is Ei, Es/Ei is 0.01 to 1.0. That is, it is preferable that the fine particles in the inner region of the particles of the porous tantalum particles are not excessively impregnated into the inside of the particles so that the fine particles are not smaller than the fine particles in the vicinity of the surface.

Further, in the porous tantalum particles, the ratio of the porosity Xs of the region S in the vicinity of the surface to the void ratio Xi of the internal region I of the particles is 0.5 to 1.5 in terms of Xs/Xi.

That is, the porous tantalum particles of the present invention have the same pore structure in the vicinity of the surface and the inner region of the particles, and the entire particles have a substantially uniform pore structure.

The fine particles 3 constituting the porous tantalum particles 1 are characterized by an average particle diameter or an average pillar diameter of 2 nm to 2 μm, and are crystalline single crystals, and contain 矽80 atom% in terms of ratios of elements other than oxygen. Above solid particles. Further, the fine particles 3 may contain a niobium alloy or an intermetallic compound containing niobium. Further, if the substantially spherical microparticles exist independently, the particle diameter can be measured, but in the case of a substantially polygonal columnar shape, the average pillar diameter or the average pillar edge corresponding to the diameter or one side of the column perpendicular to the long axis is used. .

The three-dimensional mesh structure in the present invention means a configuration in which the pores of the co-continuous structure or the sponge structure which are generated during the phase separation decomposition are connected to each other. The pore diameter of the pores having the porous cerium particles is about 0.1 to 300 nm.

The average particle diameter, average pillar diameter, and average pillar side of the fine particles 3 are 2 nm to 2 μm, preferably 10 to 500 nm, and more preferably 15 to 100 nm. Further, the average porosity of the porous cerium particles 1 is 15 to 93%, preferably 30 to 80%, and more preferably 40 to 70%.

Further, the fine particles 3 are partially joined to each other, and the area of the joined portion of the fine particles 3 is 30% or less of the surface area of the porous fine particles. That is, the surface area of the porous tantalum particle 1 is 70% or more as compared with the surface area obtained by assuming that the fine particles 3 are independently present. Further, the porous cerium particles 1 have a specific surface area of 1 to 100 m ² /g.

The porous ruthenium particles of the present invention are usually agglomerated, so micro 矽 The average particle diameter of the particles herein means the average particle diameter of the primary particles. The particle size is measured using an electron microscope (SEM) image information and a volumetric reference medium diameter of a dynamic light scattering photometer (DLS). The average particle diameter can be confirmed by SEM image, and the particle size can be obtained by image analysis software (for example, "azo-kun" (registered trademark) manufactured by Asahi Kasei Engineering), or the particles can be dispersed in a solvent and borrowed by DLS ( For example, Otsuka Electronics DLS-8000) is measured. If the particles are sufficiently dispersed during the DLS measurement and are not agglutinated, substantially the same measurement results can be obtained by SEM and DLS.

Further, since the fine particles constituting the porous cerium particles are bonded to each other, the average particle diameter is mainly determined by a surface scanning electron microscope or a transmission electron microscope.

Further, the average pillar diameter is defined as a rod-shaped (columnar) crucible particle having an aspect ratio of 5 or more, and the diameter of the column is defined as a pillar diameter. The average of the pillar diameters is taken as the average pillar diameter. The pillar diameter is mainly obtained by performing SEM observation of particles.

The average longest diameter and average shortest diameter of the 矽 microparticles were obtained after image processing using a transmission electron microscope.

First, the ruthenium particles pulverized in an agate mortar were diluted in a methanol solution by TEM observation, and the diluted droplets were dropped to a grid having a carbon coating ( 3mm) and make it dry. However, the particle weight is removed from the evaluation object.

Next, the TEM observation result and the high-resolution SEM observation result confirmed that the size of the fine particles did not change.

Moreover, the average particle diameter of the flat spherical particles is a circle similar to an elliptical particle. The area was determined, and the diameter of the particle diameter thus obtained was determined as a circle-equivalent diameter, and the average value and the standard deviation were statistically calculated.

More specifically, the long diameter and the short diameter of the fine particles are measured by TEM observation, and the average value of the long diameter and the short diameter is taken as the average longest diameter and the shortest average diameter. Further, the circle-equivalent diameter was calculated from each of the major axis and the minor axis, and the average value and the standard deviation were calculated as the average particle diameter and standard deviation of the fine particles.

The average void ratio is the ratio of the voids in the particles. The pores below the submicron can also be measured by the nitrogen adsorption method. However, when the pore size includes a wide range, it can be observed by an electron microscope, and the mercury intrusion method (JIS R 1655 "Molded by the mercury intrusion method of the fine ceramics" The measurement method of the pore size distribution is derived from the relationship between the pressure when the mercury is intruded into the void and the volume of the mercury, or the gas adsorption method (JIS Z 8830: 2001 method for measuring the specific surface area of the powder (solid) adsorbed by the gas). .

The porous tantalum particle 1 of the present invention has an average particle diameter of 0.1 μm to 1000 μm by the Si concentration of the Si intermediate alloy or the cooling rate at the time of production of the intermediate alloy. Further, the particle size is reduced by lowering the Si concentration or increasing the cooling rate. In terms of use as the negative electrode active material, the particle diameter is preferably from 0.1 to 50 μm, preferably from 1 to 30 μm, and more preferably from 5 to 20 μm. Therefore, the porous cerium particles are used as aggregates or granules in an hour. Further, when the porous cerium particles are large, there is no problem even if the porous cerium particles are roughly pulverized.

In the joint portion (joining portion) between the fine particles 3 and the adjacent fine particles 3, the thickness or diameter of the joint portion is 80% or less of the diameter of the fine particles 3 larger than the adjacent fine particles 3, and the joint portion is borrowed. Crystalline enthalpy or 矽 oxide composition. The thickness of the joint portion or the joint portion is also determined by observing the porous niobium particles by TEM.

In the connection thickness ratio, first, the thickness or diameter of the joint portion of the joined porous ruthenium particles was measured, and the larger porous ruthenium particle diameter of the two porous ruthenium particles was compared. This comparison was performed on the joint portion of the plurality of porous tantalum particles, and the average thereof was 80% or less.

Most of the fine particles 3 are oriented, and the long axis directions of most of the fine particles 3 are within ±30° of a certain direction.

(Summary of a method for producing porous cerium particles)

The outline of the manufacturing method of the porous cerium particle 1 is demonstrated using FIG.

First, in the step (a), as shown in Fig. 2 (a), the crucible intermediate alloy 7 is produced by heating and melting the crucible and the intermediate alloy element.

Then, in the step (b), the niobium intermediate alloy 7 is immersed in the molten liquid of the molten element. At this time, as shown in Fig. 2(b), the intermediate alloying element of the niobium intermediate alloy 7 is, for example, eluted into the molten liquid, and mainly forms the second phase 9 composed of the molten element, and only niobium is precipitated or crystallized as the niobium fine particles. 3. The second phase 9 is an alloy of an intermediate alloy element and a molten element, or is composed of an intermediate alloy element and a substituted molten element. The fine particles 3 are joined to each other to form a three-dimensional mesh structure.

Then, in the step (c), as shown in FIG. 2(c), when the second phase is removed by a method such as de-component etching using an acid or a base, the porous cerium particles 1 in which the cerium microparticles 3 are bonded are obtained. .

The phenomenon in each step will be described below. First, in the step (a), when the crucible and the intermediate alloy element (X) are melted and solidified, the crucible and the intermediate are formed. Gold alloy between the base alloy 7.

Then, in the step (b), when the niobium intermediate alloy is immersed in the molten element (Y) bath specified in Table 1, the molten element (Y) is permeated while being diffused into the niobium intermediate alloy, and intermediate in the niobium intermediate alloy. The alloying element (X) forms a molten element (Y) and an alloy layer as the second phase. Alternatively, the intermediate alloying element (X) in the alloy is eluted into the metal bath of the molten element (Y), and the molten element (Y) forms a new second phase. In this reaction, the ruthenium atom contained in the ruthenium intermediate alloy is left. As a result, when the germanium atom is aggregated in a nanometer size by a diffusion state, a network of germanium atoms is formed, and a three-dimensional mesh structure is formed. Further, particles having a clear facet growth were obtained under the conditions of forming a large particle size.

Further, by three-dimensional observation of a three-dimensional transmission electron microscope (for example, JEM-2100 manufactured by JEOL Ltd.), the state of bonding with the adjacent fine particles can be stereoscopically determined, and the number of joints is determined by the number of joints. It is also possible to take the coordination number from 2 to 6 as a feature.

In this step (b), there is no problem even if the joint portion containing the fine particles of the fine particles is present and the oxide is present on the surface.

Further, the primary crystal system having no alloy in the intermediate alloy has a large influence on the precipitation of the fine particles in the impregnation step (b), and acts as a core for the formation of the fine particles. Therefore, it is possible to manufacture fine particles having a large particle diameter and having the primary crystal as a core. Further, in the case of producing fine particles of 100 nm or less, it is preferable to use a composition in which the primary crystal does not exist or non-equilibrium solidification.

From the above steps, it is understood that the intermediate alloy element (X) and the molten element (Y) require the following conditions.

. Condition 1: The melting point of the molten element (Y) is 50 K or more lower than the melting point of cerium.

When the melting point of the molten element (Y) is close to the melting point of cerium, when the cerium alloy is immersed in the molten material of the molten element, cerium is dissolved in the molten metal, and therefore Condition 1 is required.

. Condition 2: Si primary crystals are not generated when the tantalum and the intermediate alloy element are solidified.

When an alloy of bismuth and an intermediate alloying element (X) is formed, a coarse ruthenium primary crystal is formed when a eutectic region is formed when the yttrium concentration is increased. The ruthenium crystal does not cause diffusion and re-aggregation of the ruthenium atoms in the impregnation step, and does not form a three-dimensional network structure.

. Condition 3: The solubility of cerium to the molten element is lower than 5 atom%.

This is because when the intermediate alloy element (X) and the molten element (Y) form the second phase, it is necessary to prevent the second phase from containing ruthenium.

. Condition 4: The intermediate alloy element and the molten element are not separated into two phases.

When the intermediate alloying element (X) and the molten element (Y) are separated into two phases, the intermediate alloying element is not separated by the cerium alloy, and no diffusion or re-aggregation of the cerium atom occurs. In addition, even if the acid treatment is carried out, an intermediate alloy element is left in the ruthenium particles.

In consideration of the above conditions 1 to 4, in order to produce porous cerium particles, a combination of an intermediate alloying element and a molten element which can be used is as follows. Further, the ratio of bismuth is 10 atom% or more of the total, and is the highest value of the maximum content of Si in the following Table 1 corresponding to the intermediate alloy element.

When Co is used as the intermediate alloying element, the content of Si is 10 to 77 atom% with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 15 to 84%.

When Cr is used as the intermediate alloying element, the content of Si is 10 to 82 atom% with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 12 to 85%.

When Cu is used as the intermediate alloying element, the content of Si is 10 to 30 atom% with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 47 to 85%.

When Fe is used as the intermediate alloying element, the content of Si is 10 to 67 atom% with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 15 to 85%.

When Mg is used as the intermediate alloying element, the content of Si is 10 to 50 atom% with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 42 to 92%.

When Mn is used as the intermediate alloying element, the content of Si is 10 to 67 atom% with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 15 to 85%.

When Mo is used as the intermediate alloying element, the content of Si is 10 to 98 atom% with respect to the sum of Si and the intermediate alloying elements, and the average porosity of the obtained porous cerium particles is 15 to 88%.

When Ni is used as the intermediate alloying element, the content of Si is 10 to 55 atom% with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 15 to 85%.

When P is used as the intermediate alloying element, the content of Si is 10 to 50% by atom with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 48 to 93%.

When Ti is used as the intermediate alloying element, the content of Si is 10 to 82 at% with respect to the sum of Si and the intermediate alloying elements, and the average porosity of the obtained porous cerium particles is 15 to 89%.

When Zr is used as the intermediate alloying element, the content of Si is 10 to 90% by atom with respect to the sum of Si and the intermediate alloying elements, and the obtained porous cerium particles have an average void ratio of 15 to 92%.

Further, although two or more of the listed elements may be used as the intermediate alloy element, in this case, a molten element corresponding to any of the intermediate alloy elements such as the intermediate alloy element is used as the molten element.

(Method for producing porous cerium particles)

Hereinafter, a method for producing the porous cerium particles of the present invention will be described.

First, heating, dissolving the enthalpy in a vacuum furnace or a non-oxidizing ambient gas furnace and selecting from the group consisting of As, Ba, Ca, Ce, Co, Cr, Cu, Er, Fe, Gd, Hf, Lu, Mg, Mn, Mo, Nb, Nd, Ni, P, Pd, Pr, Pt, Pu, Re, Rh, Ru, Sc, Sm, Sr, Ta, Te, Th, Ti, Tm, U, V, W, Y, The intermediate alloying element of 1 or more of the group consisting of Yb and Zr has a ratio of lanthanum of 10 to 98 atom%, and preferably 15 to 50 atom% of the whole. Then, using, for example, a continuous casting of a thin plate of a twin-roll casting machine or a single-roll casting machine 11 as shown in Fig. 3, the yttrium alloy 13 is dropped from the crucible 15 and the steel roller 17 is contacted with one side to be solidified and manufactured in a line shape. Or a ribbon-shaped intermediate alloy 19. In addition, the linear mother alloy can also be directly spun Manufacturing. Alternatively, unlike the linear or ribbon shape, the tantalum intermediate alloy may be formed into a foil having a certain length.

The thickness of the linear or strip-shaped tantalum intermediate alloy 19 is preferably from 0.1 μm to 2 mm, preferably from 0.1 to 500 μm, and more preferably from 0.1 to 50 μm. The cooling rate of the niobium intermediate alloy upon solidification is 0.1 K/s or more, preferably 100 K/s or more, and more preferably 400 K/s or more. This makes the particle size of the primary crystal formed at the initial stage of solidification small, thereby contributing to shortening the heat treatment time in the next step. Further, since the crystal grains of the primary crystals become small, the particle diameter of the porous tantalum particles is also reduced in proportion. Further, when the thickness of the niobium alloy (intermediate alloy) is 2 mm or more, since the Si content is high, the toughness is lacking, and cracking, disconnection, and the like are caused, which is not preferable.

Next, the bismuth intermediate alloy is immersed in a melting of Ag, Al, Au, Be, Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, Zn selected from Table 1 corresponding to the intermediate alloying elements used. In the melt of the element, a phase separation of ruthenium (precipitation of ruthenium particles), a second phase of an alloy of an intermediate alloy element and a molten element, or a second phase composed of the intermediate alloy element and the above-mentioned molten element are formed. Si fine particles are initially formed in the impregnation step. The impregnation step is, for example, a melting device 21 as shown in Fig. 4, and the belt-shaped niobium intermediate alloy 19 is immersed in the melt 23 of the molten element. Then, it is taken up by the guide roller 25 or the support roller 27. The melt 23 is heated to a temperature higher than the liquidus temperature of the molten element by 10 K or more. The immersion to the melt 23 also varies depending on the melting temperature, but is preferably 5 seconds or more and 10000 seconds or less. This is because coarse Si particles are formed when immersed for 10,000 seconds or more. Further, only the fine particles on the surface of the porous tantalum particles grow abnormally due to immersion for a long period of time. Then, in non-oxidation The strip-shaped tantalum intermediate alloy is cooled under a gaseous atmosphere. Further, as will be described later, it is preferable that the melt 23 contains no oxygen.

Then, the second phase of the alloy of the intermediate alloy element and the molten element is removed by a step of dissolving and removing at least one of an acid, a base, and an organic solvent or a step of heating and decompressing the second phase and evaporating only the second phase. Or a second phase composed of an intermediate alloy element and a substituted molten element. By removing the second phase, porous ruthenium particles are obtained. Further, the acid may be an acid which dissolves the intermediate alloy element and the molten element and does not dissolve the cerium, and examples thereof include nitric acid, hydrochloric acid, sulfuric acid and the like.

The second phase is removed by dissolving with an acid, a base, or an organic solvent, or by distillation under reduced pressure, to obtain porous cerium particles composed of fine particles. When it is dissolved by an acid, a base or an organic solvent, it is washed and dried. The particle size of 0.1 to 1000 μm is obtained by the concentration of the niobium alloy or the cooling rate at the time of production of the niobium intermediate alloy. Further, the particle size is reduced by lowering the concentration of ruthenium or increasing the cooling rate. In terms of use as the negative electrode active material, the average particle diameter thereof is preferably from 0.1 to 50 μm, preferably from 1 to 30 μm, and more preferably from 5 to 20 μm. Therefore, when the porous cerium particles are used, an aggregate or a granule is produced using a conductive binder, and the slurry is applied to the current collector. Further, when the porous cerium particles are large, there is no problem in that the porous cerium particles are roughly pulverized in a mortar. Since the microparticles are partially joined to each other, they can be easily broken.

(Another example of a method for producing porous cerium particles)

As another example of the method for producing the porous tantalum composite particle 1, a powdery, granular or massive tantalum intermediate alloy 19 may be used instead of the linear or ribbon-shaped tantalum. Intermetallic.

First, heating and dissolving the blended ruthenium in a vacuum furnace or a non-oxidizing ambient gas furnace is selected from the group consisting of As, Ba, Ca, Ce, Co, Cr, Cu, Er, Fe, Gd, Hf, Lu, Mg, Mn, Mo, Nb, Nd, Ni, P, Pd, Pr, Pt, Pu, Re, Rh, Ru, Sc, Sm, Sr, Ta, Te, Th, Ti, Tm, U, V, W, Y, The complex element of 1 or more of the group consisting of Yb and Zr has a ratio of lanthanum of 10 to 98 atom%, and preferably 15 to 50 atom% of the whole. Then, a method of producing a granular or powdery niobium intermediate alloy by a spray method as shown in FIG. 5 or a bulk ingot by the ingot production method shown in FIG. 6 and further performing mechanical pulverization A granular bismuth intermediate alloy is produced.

Fig. 5(a) shows a gas atomizing device 31 which can produce a powdery niobium intermediate alloy 39 by a gas spray method. In the crucible 33, a crucible alloy 13 having a crucible and an intermediate alloying element dissolved by induction heating or the like, and simultaneously ejecting a jet of inert gas from the gas jet 37 while being dropped from the nozzle 35, and pulverizing The melt of the niobium alloy 13 is formed into droplets and solidified to form a powdery niobium intermediate alloy 39.

Fig. 5(b) shows a rotary disc spray device 41 which can produce a powdery niobium intermediate alloy 51 by a rotary disc spray method. In the crucible 43, there is a tantalum alloy 13 of dissolved tantalum and an intermediate alloy element, and the niobium alloy is dropped from the nozzle 45, and the melt of the niobium alloy 13 is dropped to the rotating disc 49 which is rotated at a high speed, and is tangent The direction is applied by shear force to form a powdery niobium intermediate alloy 51.

Figure 6 is a view showing the formation of a massive tantalum intermediate alloy 57 by the ingot block manufacturing method. A diagram of the steps. First, the melt of the niobium alloy 13 is poured into the mold 55 by the crucible 53. Then, the tantalum alloy 13 is cooled in the mold 55, and after solidification, the mold 55 is removed and a bulk tantalum intermediate alloy 57 is obtained. The bulk tantalum intermediate alloy 57 can be pulverized as needed to obtain a granular tantalum intermediate alloy.

The thickness of the granular niobium intermediate alloy is preferably from 10 μm to 50 mm, preferably from 0.1 to 10 mm, and more preferably from 1 to 5 mm. The cooling rate of the niobium alloy when solidified is 0.1 K/s or more. Further, when the thickness of the niobium intermediate alloy is 50 mm or more, the heat treatment time becomes long, and therefore the particle diameter of the porous niobium particles grows and coarsens, which is not preferable. At this time, it is possible to perform mechanical pulverization on the bismuth intermediate alloy to be 50 mm or less.

Next, the bismuth intermediate alloy is immersed in a melting of Ag, Al, Au, Be, Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, Zn selected from Table 1 corresponding to the intermediate alloying elements used. In the melt of the element, the second phase of the phase separation of the bismuth and the alloy of the intermediate alloy element and the molten element is formed. Further, the oxygen in the melt is preferably reduced to 100 ppm or less, preferably 10 ppm or less, and more preferably 2 ppm or less. This is because dissolved oxygen in the molten metal reacts with hydrazine to form cerium oxide, and cerium is grown into a facet with the cerium oxide as a core, and is coarsened. As a countermeasure against this, it can be reduced by a solid reducing material such as charcoal or graphite or a non-oxidizing gas, or an element having a strong affinity with oxygen can be added in advance. The ruthenium microparticles are first formed in the impregnation step.

In the impregnation step, the melt impregnation device 61 shown in Fig. 7(a) is used, and the granular niobium intermediate alloy 63 is placed in the impregnation cage 65, and immersed in the melt 69 of the molten element. At this time, as shown in Fig. 7(a), the pressurizing cylinder 67 is moved up and down to impart mechanical vibration or impartance to the crucible intermediate alloy or the melt. The vibration of the ultrasonic wave can be stirred in a short time by mechanical stirring using a mechanical agitator 81 shown in Fig. 7 (b), gas injection by a gas injection plug 83, or electromagnetic stirring. Then, the non-oxidizing ambient gas is pulled down and cooled. The melt 69 or 79 is heated to a temperature higher than the liquidus temperature of the molten element by 10 K or more. The immersion to the melt also varies depending on the melting temperature, but is preferably 5 seconds or more and 10000 seconds or less. This is because coarse Si particles are formed when immersed for 10,000 seconds or more. Further, only the fine particles on the surface of the porous tantalum particles grow abnormally due to immersion for a long period of time.

Then, in the same manner as in the above production method, the second phase was removed to obtain porous tantalum particles.

(effect of porous ruthenium particles)

According to the present invention, porous ruthenium particles having a three-dimensional network structure which is not conventionally known can be obtained.

According to the present invention, porous cerium particles having a pore structure having a substantially uniform particle shape can be obtained. This is because the precipitation of the fine particles of the niobium intermediate alloy in the melt is carried out in the molten metal at a high temperature, so that the molten metal permeates into the inside of the particles.

When the porous cerium particles of the present invention are used as a negative electrode active material of a lithium ion battery, a high capacity and long life negative electrode can be obtained.

[Porous ruthenium complex particles] (Composition of porous ruthenium composite particles)

The porous tantalum particles of the present invention will be described below with reference to Fig. 8 . As shown in Fig. 8(a), the porous tantalum composite particle 101 of the present invention is composed of the fine particles 103 bonded to the ruthenium compound particles 105, and the average particles of the porous ruthenium composite particles 101. The diameter of the porous tantalum composite particles 101 is 15 to 93%, and has a three-dimensional network structure composed of continuous voids.

The three-dimensional mesh structure in the present invention means a configuration in which the pores of the co-continuous structure or the sponge structure which are generated during the phase separation decomposition are connected to each other. The pore size of the pores having the porous ruthenium complex particles is 0.1 to 300 nm.

In the porous tantalum composite particle 101, the ratio of the void ratio Xs in the vicinity of the surface in the radial direction of 50% or more to the void ratio Xi in the inner region of the particle within 50% in the radial direction is 0.5 to 1.5. .

That is, the porous tantalum composite particles of the present invention have the same pore structure in the vicinity of the surface and the inner region of the particles, and the entire particles have a substantially uniform pore structure.

The void ratio Xs can be obtained by observing the surface of the porous tantalum composite particle 101 by SEM, and the void ratio Xi can be obtained by observing the cross section of the porous tantalum composite particle 101 corresponding to the inner region of the particle by SEM.

Further, the crystal grains of the intermediate alloy are subjected to the de-component etching and the change in the step (c) of the molten element in the step (b) described later to obtain a porous crucible having a size equivalent to that of the intermediate alloy. Composite particles (not pulverized to make them micronized). The porous tantalum composite particles 101 are divided into a surface vicinity region S in the radial direction of 90% or more and a particle inner region I in the radial direction of 90% or less, and the average particle diameter of the fine particles 103 constituting the region S in the vicinity of the surface is Es, and when the average particle diameter of the fine particles 103 constituting the inner region I of the particles is Ei, Es/Ei is preferably from 0.01 to 1.0. which is, It is preferable that the fine particles in the inner region of the particles of the porous tantalum particles are not excessively impregnated into the inside of the particles in such a manner that they are not smaller than the fine particles in the vicinity of the surface.

The one side of the average particle diameter or the average pillar diameter of the fine particles 103 is 2 nm to 2 μm, preferably 10 to 500 nm, and more preferably 20 to 300 nm. Further, the average void ratio is 15 to 93%, preferably 50 to 80%, and more preferably 60 to 70%. Further, the crystal structure of the fine particles 103 one by one has a single crystal of crystallinity. In addition, the fine particles 103 contain 矽80 atom% or more in terms of the ratio of elements other than oxygen, and the remaining solid particles containing an intermediate alloy element, a molten element, and other unavoidable impurities to be described later.

The shape of the fine particles 103 is preferably spherical or polygonal, and the particle diameter of the fine particles 103, the average diameter of the pillar diameter or the pillar side is 2 nm to 2 μm, and the particle diameter of the fine particles 103, the pillar diameter or the pillar edge. The standard deviation σ is 1 to 500 nm, and the ratio of the average x to the standard deviation σ (σ/x) is 0.01 to 0.5.

The shape of the fine particles 103 has a flat spherical shape, a cylindrical shape or a polygonal column shape, and the ratio (a/b) of the average longest diameter or the longest side a to the average shortest diameter or the shortest side b is 1.1 to 50.

Further, as shown in FIG. 8(b), the porous tantalum composite particles 101 are divided into a surface vicinity region S in the radial direction of 50% or more and a particle inner region I in the radial direction of 50% or less, and the porous structure is formed. When the average particle diameter of the fine particles in the vicinity of the surface of the composite particles is Ds, and the average particle diameter of the fine particles in the inner region of the particles constituting the porous tantalum composite particles is Di, Ds/Di is 0.5 to 1.5.

The average particle diameter Ds can be obtained by observing the surface of the porous tantalum composite particle 1 by SEM, and the average particle diameter Di can be obtained by observing the cross section of the porous tantalum composite particle 1 corresponding to the inner region of the particle by SEM.

The average particle diameter of the cerium compound particles 105 is 50 nm to 50 μm, and preferably 100 nm to 20 μm, and more preferably 200 nm to 10 μm. Further, the composition is selected from the group consisting of As, Ba, Ca, Ce, Co, Cr, Cu, Er, Fe, Gd, Hf, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, Pr a composite element of one or more groups consisting of Pt, Pu, Re, Rh, Ru, Sc, Sm, Sr, Ta, Te, Th, Ti, Tm, U, V, W, Y, Yb, and Zr, 50 to 75 atom% of solid and crystalline intermediate particles composed of an intermediate alloy element, a molten element, and other unavoidable impurities described later. Further, the ruthenium compound particles 105 are usually larger than the ruthenium particles 103.

Further, even on the surface of the porous tantalum composite particle 101, that is, the fine particles 103 or the ruthenium compound particles 105, the thickness is 20 nm or less, or the particle size ratio of each of the fine particles 103 or the ruthenium compound particles 105 is 10% or less. The oxide layer has no problem in terms of characteristics.

Further, the oxide layer on the surface of the porous tantalum composite particle 101 can be formed by immersing nitric acid at 0.0001 to 0.1 N after removing the second phase. Alternatively, it may be formed under the partial pressure of oxygen of 0.00000001 to 0.02 MPa after the second phase is removed. When the oxide layer of the tantalum is formed, the porous tantalum composite particles 101 are extremely stable even in the atmosphere, and do not need to be processed in a handle box.

The porous tantalum composite particles of the present invention are usually aggregated, and thus the average particle diameter of the particles means the average particle diameter of the primary particles. The particle size is measured using an electron microscope (SEM) image information and a volumetric reference medium diameter of a dynamic light scattering photometer (DLS). The average particle size can be confirmed by SEM image first, and the image analysis software (for example, "A image by Asahi Kasei Engineering" (Registered Trademark)) The particle size is determined, or the particles are dispersed in a solvent and measured by DLS (for example, DLS-8000 manufactured by Otsuka Electronics Co., Ltd.). If the particles are sufficiently dispersed during the DLS measurement and are not agglutinated, substantially the same measurement results can be obtained by SEM and DLS.

Further, since the fine particles of the porous cerium composite particles and the cerium compound particles are bonded to each other, the average particle diameter is mainly determined by a surface scanning electron microscope or a transmission electron microscope.

Further, the average pillar diameter is defined as a rod-shaped (columnar) crucible particle having an aspect ratio of 5 or more, and the diameter of the column is defined as a pillar diameter. The average of the pillar diameters is taken as the average pillar diameter. The pillar diameter is mainly obtained by performing SEM observation of particles.

The average void ratio is the ratio of the voids in the particles. The pores below the submicron can also be measured by the nitrogen adsorption method, but when the pore size includes a wide range, it can be observed by electron microscopy or mercury intrusion method (JIS R 1655 "Formed by mercury intrusion method of fine ceramics" The measurement method of the pore diameter distribution is derived from the relationship between the pressure when mercury is intruded into the space and the volume of mercury. Further, the BET specific surface area can be measured by a nitrogen gas adsorption method.

The porous tantalum composite particle 101 of the present invention has a Si concentration of the Si intermediate alloy or a cooling rate at the time of production of the intermediate alloy of 0.1 μm to 1000 μm. Further, the particle size is reduced by lowering the Si concentration or increasing the cooling rate. In terms of use as the negative electrode active material, the particle diameter is preferably from 0.1 to 50 μm, preferably from 1 to 30 μm, and more preferably from 5 to 20 μm. therefore, The porous cerium particles are used as aggregates or granules in hours. Further, when the porous cerium particles are large, there is no problem even if the porous cerium particles are roughly pulverized.

In the joint portion between the fine particles 103 and the adjacent fine particles 103, the thickness or diameter of the joint portion is 80% or less of the diameter of the fine particles 103 larger than the adjacent fine particles 103, and the joint portion is crystallized or矽 oxide composition.

Most of the fine particles 103 are oriented, and the long axis directions of most of the fine particles 103 are within ±30° of a certain direction.

The measurement system is mainly performed, for example, the SEM image of Figs. 22 and 23, and the orientation angle is defined by the deviation of the average value of the angle of the growth direction.

(Summary of the first manufacturing method of the porous ruthenium composite particles)

The outline of the manufacturing method of the porous cerium particle 101 is demonstrated using FIG.

First, as shown in FIG. 9(a), the tantalum intermediate alloy 107 is produced by heating, melting the tantalum, the intermediate alloy element, and the composite element. At this time, the tantalum, the composite element, and the intermediate alloy element are melted and solidified, that is, the intermediate alloy 107 of the tantalum, the composite element and the intermediate alloy element, and the tantalum compound particle composed of the tantalum and the composite element are formed.

Then, the niobium intermediate alloy 107 is immersed in the molten liquid of the molten element. When the tantalum intermediate alloy 107 is immersed in the molten metal bath, the molten element is impregnated into the tantalum intermediate alloy 107. At this time, the intermediate alloy element forms an alloy solid phase with the molten element, and further penetrates the molten element to form a liquid phase. A ruthenium atom and a complex element are left in the liquid phase region. When the germanium atom or the complex element is aggregated by the diffusion state, the fine particles 103 are precipitated. And forming a network of alloys of germanium atoms and complex elements, and forming a three-dimensional mesh structure. That is, as shown in FIG. 9(b), the intermediate alloy element of the niobium intermediate alloy 107 is eluted into the molten metal, for example, and the second phase 109 is formed, and the niobium fine particles 103 are decanted. The second phase 109 is an alloy of an intermediate alloy element and a molten element, or an intermediate alloy element and a substituted molten element. Further, the cerium compound particles 105 are left as they are without being affected by the melt of the molten element. The fine particles 103 and the ruthenium compound particles 105 are bonded to each other to form a three-dimensional network structure.

Further, in the step of immersing in the molten metal bath, even if the ruthenium primary crystal alone, or the compound of the ruthenium and the composite element is impregnated with the molten element, no re-aggregation of the ruthenium atom or the composite element occurs, and the ruthenium primary crystal Or the compound of the complex element is left as it is. Therefore, it is preferable to increase the cooling rate when the crucible intermediate alloy 107 is produced, and to perform such particle diameter control.

Then, as shown in FIG. 9(c), when the second phase 109 is removed by a method such as de-ion etching using an acid or a base, the porous ruthenium complex particles in which the ruthenium fine particles 103 and the ruthenium compound particles 105 are bonded are obtained. 1.

From the above steps, the following conditions are required for the intermediate alloy element, the composite element, and the molten element.

‧Condition 1: The melting point of the molten element is 50 K or more lower than the melting point of 矽.

When the melting point of the molten element is close to the melting point of cerium, when the cerium intermediate alloy is immersed in the molten material of the molten element, cerium is dissolved in the molten metal, and therefore Condition 1 is required.

‧Condition 2: Si primary crystals are not produced when the tantalum and the intermediate alloy elements are solidified.

When an alloy of tantalum and an intermediate alloy element is formed, an increase in the concentration of niobium is formed. A coarse ruthenium crystal is formed in the hypereutectic region. The ruthenium crystal does not cause diffusion and re-aggregation of the ruthenium atoms in the impregnation step, and does not form a three-dimensional network structure.

‧Condition 3: The solubility of bismuth to the intermediate alloy element and the molten element is lower than 5 atom%.

This is because when the intermediate alloy element forms a second phase with the molten element, it is necessary to prevent the second phase from containing ruthenium.

‧Condition 4: The intermediate alloy element and the molten element are not separated into two phases.

When the intermediate alloy element and the molten element are separated into two phases, the intermediate alloying element is not separated by the niobium alloy, and no diffusion or re-aggregation of the niobium atom occurs. In addition, even if the acid treatment is carried out, an intermediate alloy element is left in the ruthenium particles.

‧Condition 5: The ruthenium and the composite element are not separated into two phases.

When the ruthenium and the composite element are easily separated into two phases, the ruthenium compound particles composed of the alloy of ruthenium and the composite element are not finally obtained.

‧ Condition 6: The intermediate alloying element corresponding to the molten element does not contain the complex element in the selectable element.

The composite element may be selected as an element of an intermediate alloy element, and when it has the characteristics of the intermediate alloy element as described above, the molten element and the composite element form a second phase, and the composite element is removed when the acid treatment is performed.

When the above conditions 1 to 6 are considered, the void ratio of the intermediate alloy element, the composite element, the molten element, and the obtained porous tantalum composite particle which can be used for producing the porous tantalum composite particles is as follows. Further, the ratio of the composite elements is from 1 to 33 atom%. Further, the ratio of ruthenium is 10 atom% or more relative to the sum of the ruthenium, the intermediate alloy element, and the aforementioned composite element, and The value of the maximum content of Si in the following Table 2 corresponding to the intermediate alloy element (when a plurality of intermediate alloy elements are contained, the value of the maximum content of Si in Table 2 corresponding to each intermediate alloy element is assigned according to the ratio of the intermediate alloy elements) . A composite element that can be used in common is used in each of the intermediate alloy elements.

In the step of forming the ruthenium intermediate alloy 107, ruthenium (X atom%), intermediate alloy element (Y atom%), and 1 or more complex elements (Z ₁ , Z ₂ , Z ₃ , . . atomic %) are preferably A niobium intermediate alloy having a composition satisfying the following formula was produced. Further, [the maximum content of Si] corresponds to the value of the maximum content of Si in the above-mentioned Table 2 of the intermediate alloy element, and when there are a plurality of intermediate alloy elements, the maximum content of Si of each intermediate alloy element is assigned according to the ratio of each intermediate alloy element. value. Further, when there are many intermediate alloy elements, the sum of the Y atom% is the ratio of the majority of the intermediate alloy elements.

10≦X<[maximum content of Si] (1)

10≦a÷(a+Y)×100≦[Si maximum content] (2)

However, a=X-1.5×(Z ₁ +Z ₂ +Z ₃ ,....)

(First manufacturing method of porous ruthenium composite particles)

Hereinafter, a method for producing the porous ruthenium composite particles of the present invention will be described. In the following, the device used in the method for producing porous ruthenium composite particles will be described, and the same symbols will be given to the respective intermediate alloys. However, in the case of containing the composite elements, the intermediate alloy for producing the porous ruthenium composite particles is used. It is different from the intermediate alloy used to make porous tantalum particles.

First, an intermediate alloy element selected from the group consisting of Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Ti, and Zr described in Table 2, and a corresponding intermediate alloy are used. The composite element of 1 or more described in Table 2 of the element is heated and dissolved in a vacuum furnace or the like to dissolve a mixture of ruthenium, an intermediate alloy element, and a composite element. At this time, an alloy of bismuth and an intermediate alloy element, and a compound of ruthenium and a complex element are formed.

Then, for example, a single roll casting machine 11 as shown in Fig. 3 is used, 15 The molten yttrium alloy 13 was dropped, and the steel roll 17 was brought into contact with one another to solidify it, and a belt-shaped yttrium intermediate alloy 19 or a yttrium intermediate alloy was produced. The cooling rate at which the niobium intermediate alloy solidifies is 10 K/s or more, preferably 100 K/s or more, and more preferably 200 K/s or more. The increase in the cooling rate contributes to the microstructural reduction of the ruthenium compound particles formed in the early stage of solidification. Reducing the size of the ruthenium compound particles helps to shorten the heat treatment time in the next step. The thickness of the strip-shaped tantalum intermediate alloy 19 or the linear tantalum intermediate alloy is 0.1 μm to 2 mm, preferably 0.1 to 500 μm, and more preferably 0.1 to 50 μm. Alternatively, unlike the linear or ribbon shape, the tantalum intermediate alloy may be formed into a foil having a certain length. Further, the average size of the microstructure of the intermediate alloy is preferably from 0.1 μm to 1 mm, preferably from 0.1 to 500 μm, and more preferably from 0.1 to 300 μm. This is because the bath element preferentially diffuses through the crystal grain boundary when immersed in the molten metal bath in the step (b), and then diffuses in the grain boundary.

Next, the bismuth intermediate alloy is immersed in at least one selected from the group consisting of Ag, Al, Au, Be, Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, and Zn corresponding to the intermediate alloying elements described in Table 2. In the above metal bath of the molten element, Si is decomposed out of phase, and a second phase of an alloy of an intermediate alloy element and a molten element or a second phase composed of the intermediate molten element and the substituted molten element is formed. The impregnation step is, for example, the use of the melting device 21 as shown in FIG. 4, and the belt-shaped niobium intermediate alloy 19 or the linear niobium intermediate alloy is immersed in the molten liquid 23 of the molten element. Then, it is taken up by the guide roller 25 or the support roller 27. The melt 23 is heated to a temperature higher than the liquidus temperature of the molten element by 10 K or more. The immersion to the melt 23 also varies depending on the melting temperature, but is preferably 5 seconds or more and 10000 seconds or less. This is because the immersion is performed for more than 10,000 seconds. Coarse Si particles. Further, only the fine particles on the surface of the porous tantalum particles grow abnormally due to immersion for a long period of time. Next, the entangled ruthenium intermediate alloy 19 is cooled under a non-oxidizing atmosphere gas, and a composite of ruthenium fine particles 103, ruthenium compound particles 105, and second phase 109 is obtained.

Then, the second phase 109 in which the alloy of the intermediate alloy element and the molten element is dissolved by at least one of an acid, a base, and an organic solvent, or the second phase 109 composed of the intermediate alloy element and the aforementioned molten element is substituted, and only the second phase is removed. The phase 109 is also washed and dried. The acid may be an acid which dissolves the intermediate alloy element and the molten element and does not dissolve the cerium, and examples thereof include nitric acid, hydrochloric acid, sulfuric acid, and the like. Alternatively, the second phase 109 may be removed by heating under reduced pressure and evaporated to remove the second phase.

Further, after the removal of the second phase 109, coarse aggregates of the porous tantalum composite particles 101 are obtained. Therefore, the aggregates are pulverized by a ball mill or the like to have an average particle diameter of the aggregates of 0.1 μm to 20 μm.

(Another example of the first manufacturing method of the porous tantalum composite particle 101)

In another example of the first method for producing the porous tantalum composite particles 101, a powdery, granular or massive tantalum intermediate alloy may be used instead of the linear or strip-shaped tantalum intermediate alloy 19.

First, an intermediate alloy element selected from the group consisting of Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Ti, and Zr described in Table 2, and a corresponding intermediate alloy are used. The composite element of 1 or more described in Table 2 of the element is heated and dissolved in a vacuum furnace or the like to dissolve a mixture of ruthenium, an intermediate alloy element, and a composite element.

Then, a method of producing a granular or powdery niobium intermediate alloy by a spray method as shown in FIGS. 5(a) and (b) or a bulk ingot using the ingot production method shown in FIG. 6 is carried out, and further if necessary A powdery, granular or massive niobium intermediate alloy is produced by mechanical pulverization.

Fig. 5(a) shows a gas atomizing device 31 which can produce a powdery niobium intermediate alloy 39 by a gas spray method. In the crucible 33, the crucible alloy 13 having a crucible, an intermediate alloying element, and a composite element dissolved by induction heating or the like is sprayed and supplied with an inert gas or air, etc., simultaneously with dropping the niobium alloy 13 from the nozzle 35. The jet stream 38 from the gas jet machine 37 is pulverized, and the melt of the niobium alloy 13 is pulverized to form droplets and solidified to form a powdery niobium intermediate alloy 39.

Fig. 5(b) shows a rotary disc spray device 41 which can produce a powdery niobium intermediate alloy 51 by a rotary disc spray method. In the crucible 43, the niobium alloy 13 having the dissolved niobium, the intermediate alloying element, and the composite element is dropped, and the niobium alloy is dropped from the nozzle 45, and the molten metal of the niobium alloy 13 is dropped to the rotating disc 49 which is rotated at a high speed. Further, shearing force is applied in a tangential direction to form a powdery niobium intermediate alloy 51.

Fig. 6 is a view for explaining the steps of forming the bulk tantalum intermediate alloy 57 by the ingot casting method. First, the melt of the niobium alloy 13 is poured into the mold 55 by the crucible 53. Then, the tantalum alloy 13 is cooled in the mold 55, and after solidification, the mold 55 is removed and a bulk tantalum intermediate alloy 57 is obtained. The bulk tantalum intermediate alloy 57 may be used as it is, or may be pulverized as needed, and used as a granular tantalum intermediate alloy.

The particle size of the powdery, granulated or massive base alloy is preferably from 10 μm to 50 mm, preferably from 0.1 to 10 mm, and more preferably from 1 to 5 mm.矽 The cooling rate of the alloy during solidification is 0.1 K/s or more. Further, when the thickness of the niobium intermediate alloy is 50 mm or more, since the heat treatment time is long, the particle size of the porous niobium composite particles grows and coarsens, which is not preferable. At this time, it is possible to perform mechanical pulverization on the bismuth intermediate alloy to be 50 mm or less.

The intermediate alloy composed of the niobium and the intermediate alloy element or the composite element preferably has a crystal grain size of 1000 μm or less, preferably 500 μm or less, and more preferably 50 μm or less. When the crystal grain size is 1000 μm or more, the grain boundary diffusion of the molten element in the step (b) is preferentially carried out, and the intragranular diffusion is stagnated, so that a homogeneous reaction cannot be produced.

Next, the niobium intermediate alloy is immersed in the melt of the molten element described in Table 2 corresponding to the intermediate alloy element used, and the second phase of the phase-decomposed and alloy of the intermediate alloy element and the molten element is formed. Further, the oxygen in the melt is preferably reduced to 100 ppm or less, preferably 10 ppm or less, and more preferably 2 ppm or less. This is because dissolved oxygen in the molten metal reacts with hydrazine to form cerium oxide, and cerium is grown into a facet with the cerium oxide as a core, and is coarsened. As a countermeasure against this, it can be reduced by a solid reducing material such as charcoal or graphite or a non-oxidizing gas, or an element having a strong affinity with oxygen can be added in advance. The ruthenium microparticles are first formed in the impregnation step.

In the impregnation step, the melt impregnation device 61 shown in Fig. 7(a) is used, and the granular niobium intermediate alloy 63 is placed in the impregnation cage 65, and immersed in the melt 69 of the molten element. At this time, as shown in Fig. 7 (a), the pressurizing cylinder 67 is placed up and down, and the mechanical vibration of the intermediate alloy or the molten metal or the vibration of the ultrasonic wave is applied, and the mechanical agitator shown in Fig. 7 (b) is used. Mechanical stirring of 81, gas injection by means of gas blowing into the plug 83 or electromagnetic stirring and melting Liquid, whereby the reaction can be carried out in a short time. Then, the non-oxidizing ambient gas is pulled down and cooled. The melt 69 or 79 is heated to a temperature higher than the liquidus temperature of the molten element by 10 K or more. The immersion to the melt also varies depending on the melting temperature, but is preferably 5 seconds or more and 10000 seconds or less. This is because coarse Si particles are formed when immersed for 10,000 seconds or more. Further, only the fine particles on the surface of the porous tantalum particles grow abnormally due to immersion for a long period of time. In addition, the above-mentioned powdery, granular, and block-shaped shapes of the niobium intermediate alloy are simply powders, granules, and blocks which are small in aspect ratio (length to width ratio of 5 or less) by size, and are not strictly Ground definition. Further, the granular niobium intermediate alloys 63, 73, and 93 are represented by the above-mentioned powdery, granular, or bulk niobium intermediate alloy and described as a granular niobium intermediate alloy.

Then, in the same manner as the above production method, the second phase is removed to obtain porous tantalum composite particles.

(Second manufacturing method of porous ruthenium composite particles)

Next, a second method for producing the porous ruthenium composite particles of the present invention will be described. In the second manufacturing method, as shown in Fig. 10 (a), a tantalum intermediate alloy 111 composed of tantalum and an intermediate alloy element is formed. Then, in the molten liquid in which the composite element is added by immersion in the molten element, as shown in FIG. 10(b), the fine particles 103, the ruthenium compound particles 105, and the second phase 109 are formed. Then, as shown in FIG. 10(c), the second phase 109 is removed and the porous tantalum composite particles 101 are obtained.

Hereinafter, the second manufacturing method will be specifically described.

First, the powder of the cerium is dissolved, and the powder of the intermediate alloying element selected from the group consisting of Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Ti, and Zr described in Table 2 , making 矽 (X atom%), intermediate alloying elements (Y atom%) satisfies the formula (3).

X÷(X+Y)×100≦[maximum content of Si] (3)

Then, similarly to the first manufacturing method, a strip-shaped tantalum intermediate alloy 19 or a linear intermediate alloy element of an alloy of niobium and an intermediate alloy element is produced using a single roll casting machine 11 as shown in FIG. Alternatively, a powdery intermediate alloy element is produced by a spray method as shown in Figs. 5(a) and (b). Further, as shown in Fig. 6, the niobium intermediate alloy may be cast into an ingot, and the ingot may be mechanically pulverized into pellets.

Then, the bismuth intermediate alloy is immersed in a composite element corresponding to one or more of the intermediate alloy elements described in Table 2, and each of 10 atom% or less is added, and a total of 20 atom% or less is added to the Ag corresponding to the intermediate alloy element described in Table 2. In the alloy bath made of at least one or more of the molten elements of at least one of Al, Au, Be, Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, and Zn, the phase separation of Si is formed, and the Si and the composite are formed. The shape of the compound of the element, the second phase of the alloy of the intermediate alloy element and the molten element, and/or the second phase formed by the intermediate alloy element and the substituted molten element. The impregnation step is, for example, immersing the strip-shaped tantalum intermediate alloy 19 or the linear tantalum intermediate alloy in the molten material 23 of the molten element using the melt impregnation device 21 as shown in FIG. 4, or using the liquid as shown in FIG. The melt impregnation apparatus or the melt treatment apparatus immerses the granular niobium intermediate alloy in the molten liquid of the molten element. The melt 23 is heated to a temperature higher than the liquidus temperature of the molten element by 10 K or more. The immersion to the melt 23 also varies depending on the melting temperature, but is preferably 5 seconds or more and 10000 seconds or less. This is because coarse Si particles are formed when immersed for 10,000 seconds or more. Further, only the fine particles on the surface of the porous tantalum particles grow abnormally due to immersion for a long period of time. In non- The ribbon-shaped tantalum intermediate alloy is cooled under an oxidizing atmosphere, and a composite of the fine particles 103, the ruthenium compound particles 105, and the second phase 109 is obtained.

Further, the niobium intermediate alloy may be immersed in a bath of the molten element described in Table 2 corresponding to the intermediate alloy element, and then immersed in a composite element selected from the group consisting of Table 2 corresponding to the intermediate alloy element. One or more of the composite elements of the group are added in an amount of 10 atom% or less, and a total of 20 atom% or less is added to the alloy bath prepared in the molten element described in Table 2 of the intermediate alloy element.

Further, in the step (b), the preferential growth orientation inherent to the metal of the molten metal bath as shown in Table 3 is the dominant factor, and the orientation of the fine particles can be controlled. Further, even if the second phase is removed in the step (c), the orientation of the fine particles can be maintained. Therefore, by selecting a molten metal bath, the orientation of the ruthenium particles can be controlled.

Further, although the reason is not clear, the growth orientation of the molten element is preferably <1010>.

Fig. 22 is a SEM photograph showing a cross section of the fine particles and the second phase which are immersed in the molten metal in the step (b) of the first to fifth embodiments to be described later. The black area that is seen contains the second phase of the sputum, and the white areas that are seen are sputum particles. It can be understood that the 矽 microparticles are arranged in the upper right direction of the figure. This is because when the second phase is formed, the fine particles are formed along the <1010> of the crystal orientation which is easy to grow.

Fig. 23 is a SEM photograph showing the fine particles of the surface of the porous tantalum particles after the second phase is removed after the step (c) of the second to fifth embodiments. It can be understood that the flat cylindrical cymbal particles are arranged in the upper left direction of the figure.

Then, in the same manner as the first production method described above, only the second phase 109 is removed, and the porous tantalum composite particles 101 are obtained.

(Effect of porous ruthenium complex particles)

According to the present invention, porous ruthenium complex particles having a three-dimensional network structure which is not conventionally known can be obtained.

According to the present invention, it is possible to obtain porous tantalum composite particles having a fine pore structure in which the entire particles are substantially uniform. This is because the precipitation of the fine particles of the niobium intermediate alloy in the melt is carried out in the molten metal at a high temperature, so that the molten metal permeates into the inside of the particles.

When the porous cerium particles of the present invention are used as a negative electrode active material of a lithium ion battery, a high capacity and long life negative electrode can be obtained. In particular, compared with ruthenium, the composite element is an element which does not easily adsorb lithium. Therefore, when the lithium ion is adsorbed, the composite element is difficult to swell, so that the expansion of the ruthenium can be suppressed, and the negative electrode of a longer life can be obtained. Moreover, compared with ruthenium, the ruthenium compound particles of the compound of ruthenium and the complex element have high conductivity, and thus are compared with the general ruthenium particle ratio. In contrast, the porous tantalum composite particles of the present invention can be charged and discharged by an emergency speed.

Example

Hereinafter, the present invention will be specifically described using examples and comparative examples. Examples 1-1 to 1-16 are examples relating to porous cerium particles, and Examples 2-1 to 2-16 are examples relating to porous cerium composite particles containing a composite element.

[Example 1] (Example 1-1)

Niobium (blocky, purity: 95.0% or more) and cobalt were blended at a ratio of Si:Co=55:45 (atomic %), and dissolved in a vacuum oven at 1480 °C. Then, it was rapidly cooled at a cooling rate of 800 K/s using a single roll casting machine to produce a ruthenium alloy tape having a thickness of 200 μm. The niobium alloy ribbon was immersed in a tin melt at 940 ° C for 1 minute, and immediately quenched in argon gas. By this treatment, a two-phase composite of the second phase composed of Si and Co-Sn or Sn is obtained. The two-phase composite was immersed in a 20% aqueous solution of nitric acid for 5 minutes to obtain porous cerium particles.

(Examples 1-2 to 1-11)

The manufacturing conditions of the respective examples and comparative examples are summarized in Table 4. In the examples 1-2 to 1-11, the porous ruthenium composite particles were obtained in the same manner as in the method of Example 1-1 except that the intermediate alloy elements shown in Table 4 and the blending ratio of each element were used.

(Examples 1-12)

Niobium (blocky, purity: 95.0% or more) and magnesium were blended in a ratio of Si:Mg = 12:88 (atomic %), and dissolved in a vacuum oven at 1090 °C. Then, it was cooled in a mold, and an ingot made of a 5 mm square bismuth alloy was produced. The niobium alloy ingot was immersed in a lead melt at 470 ° C for 1 minute, and then immediately quenched in argon gas. By this treatment, a two-phase composite of the second phase composed of Si and Mg-Pb or Pb is obtained. The two-phase composite was immersed in a 20% aqueous solution of nitric acid for 5 minutes to obtain porous cerium particles.

(Examples 1-13 to 1-16)

In the examples 1-13 to 1-16, the porous tantalum composite particles were obtained in the same manner as in the method of Example 1-12 except that the intermediate alloy elements shown in Table 4 and the blending ratio of each element were used.

(Comparative Example 1-1)

The cerium powder and the magnesium powder were blended in a ratio of Si:Mg = 55:45 (atomic %), and dissolved in an argon atmosphere at 1087 °C. Then, using a twin-roll casting machine, it was rapidly cooled at a cooling rate of 200 K/s, and a tape made of a tantalum alloy having a thickness of 1 mm was produced. The tantalum alloy tape was immersed in a 890 ° C mash melt for 1 minute, and immediately quenched in argon gas. The composite was immersed in a 20% aqueous solution of nitric acid for 5 minutes.

(Comparative Example 1-2)

An etch treatment of ruthenium particles (SIE23PB, manufactured by High Purity Chemical Research Laboratory Co., Ltd.) having an average particle diameter of 5 μm was carried out by mixing a mixed acid of 20 wt% of hydrogen fluoride water and 25 wt% of nitric acid, and the porous ruthenium particles were obtained by filtration.

(Comparative Example 1-3)

Antimony particles having an average particle diameter of 5 μm (SIE23PB, manufactured by High Purity Chemical Research Laboratory) were used.

[Evaluation]

The evaluation results are summarized in Table 5. Further, since Examples 1-13 to 1-16 were large in ruthenium particles, the particles which were pulverized and reduced in the mortar were used for evaluation of characteristics. For example, 130 of the particle size of the porous tantalum particles of Examples 1-13 33 means that porous cerium particles having an average particle diameter of 130 μm are pulverized and porous cerium particles having an average particle diameter of 33 μm are obtained.

As shown in Table 5, the average particle diameter x of the fine particles of each example is 2 nm to 2 μm, and the standard deviation σ of the particle diameter of the fine particles is 1 to 500 nm, and the ratio of the average x to the standard deviation σ (σ/x). It is 0.01 to 0.5. Further, in each of the examples, the ratio (a/b) of the average longest diameter a to the average shortest diameter b is 1.1 to 50. Further, the ratio of the thickness of the connection portion between the fine particles and the adjacent fine particles to the diameter of the fine particles larger than the adjacent fine particles (the thickness ratio of the joint) is 80% or less.

In each of the examples, the porous ruthenium particles satisfying the requirements described in the first item of the patent application range were produced by a manufacturing method using de- ing etching (dealloying), so that after 50 cycles in each of the examples The capacity retention rate is high and the cycle characteristics are good. Since the particle size of the ruthenium particles is uniform, no stress is concentrated on the uneven portion of the particle size during expansion and contraction of the active material during charge and discharge, and therefore it is estimated that the cycle characteristics are greatly improved.

Since the capacity retention ratio after 50 cycles of each embodiment is higher than that of Comparative Examples 1-1 to 1-3, and the ratio of the discharge capacity reduction due to the reverse charge and discharge is small, it is expected that the life of the battery is long.

Further, in each of the examples, the negative electrode active material has porous ruthenium particles having a three-dimensional network structure or a continuous void, and therefore, even if it is caused by alloying and de-alloying of Li and Si during charge and discharge, the volume of expansion and contraction is caused. The change does not cause cracking or micronization of the ruthenium particles, and the discharge capacity retention rate is high.

In a more detailed comparison, in Comparative Example 1-1, pure Si crystal was used as the primary crystal in the preparation of the intermediate alloy, and a eutectic structure (Si and Mg ₂ Si) was further formed at the end of solidification. The primary Si is thick to about 10 μm. Even if the primary crystal is immersed in the cerium melt, it is not refined, but coarsened, and remains in the original shape even after the etching step. Therefore, when Li repeatedly invades and releases, the Si monomer including coarse Si cannot be combined with the volume change of expansion and contraction caused by alloying and de-alloying of Li and Si, causing cracking or collapse, and loss of set. The ratio of the electrical path or the electrode function becomes large, and it can be considered that the battery life is shortened.

In Comparative Example 1-2, since the pore structure was formed by etching with hydrofluoric acid or nitric acid, a place where pores were not formed was formed in the center portion of the particle. The part of the core cannot be matched with the volume change of charge and discharge, and it is considered that the cycle characteristics are poor.

In Comparative Example 1-3, since it is merely a ruthenium particle having no pore structure, the volume change of charge and discharge cannot be matched, and it is considered that the cycle characteristics are poor.

(Evaluation of particle shape)

The particle shape of the porous cerium particles was observed using a transmission electron microscope (JEM 3100FEF manufactured by JEOL Ltd.). SEM photographs of the particles of Examples 1-12 are shown in Fig. 11, and SEM photographs of the particles of Comparative Example 1-1 are shown in Fig. 12. In Fig. 11, it is observed that the ruthenium particles having a particle diameter of 20 nm to 100 nm are bonded to each other and aggregated in a large amount, and porous ruthenium particles are formed. On the other hand, in Fig. 12, a wall structure having a thickness of about 5 μm was observed.

The average particle size of the bismuth microparticles is measured by image information of an electron microscope (SEM). Further, the porous tantalum particles are divided into a region near the surface in the radial direction of 50% or more and a region inside the particle having a radius of 50% or less, and the ratio of the respective average particle diameters Ds to Di is calculated. In the embodiment, the value of Ds/Di is between 0.5 and 1.5, but in Comparative Example 1-2 obtained by the etching method In comparison with the inner region of the particle, the average particle diameter of the microparticles in the vicinity of the surface is small, and the value of Ds/Di becomes small.

The Si concentration of the cerium microparticles and the porous cerium particles was measured by an ICP luminescence spectrometer. All contain 矽80 atom% or more.

The average void ratio of the porous cerium particles was measured by a mercury intrusion method (JIS R 1655) using a 15 mL unit.

Further, the porous tantalum particles are divided into a region near the surface in the radial direction of 50% or more and an inner region of the particles having a radius of 50% or less, and the respective average void ratios Xs and Xi are measured by the image information of the SEM. Calculate the ratio of Xs to Xi. In the examples, the value of Xs/Xi is between 0.5 and 1.5, but in Comparative Example 1-2 obtained by the etching method, the pore structure in the vicinity of the surface is developed in comparison with the internal region of the particle, so Xs/Xi The value becomes larger.

Further, Fig. 13 is an X-ray diffraction grating image for measuring the fine particles of the porous tantalum particles constituting Examples 1-12. By observing the diffraction generated by the ruthenium crystal, the diffraction of the dots is obtained, and it is understood that the ruthenium microparticles are composed of a single crystal.

(Evaluation of cycle characteristics when particles are used for the negative electrode) (i) Modulation of negative electrode slurry

40 parts by mass of the particles of the examples or the comparative examples were put into a mixer at a ratio of 45 parts by mass of acetylene black (manufactured by Electric Chemical Industry Co., Ltd.). Then, an emulsifier (made by ZEON Co., Ltd., BM400B) of 40 parts by mass of styrene butadiene rubber (SBR) was mixed as a binder in a ratio of 5 parts by mass of solid content to 10 parts by mass of solid content, and A 1% by mass solution of sodium carboxymethylcellulose (manufactured by DAICEL CHEMICAL INDUSTRIES) was used as a tackifier for adjusting the viscosity of the slurry to prepare a slurry.

(ii) Production of negative electrode

A 10 μm-thickness-modulated slurry was applied to an electrolytic copper foil for a current collector having a thickness of 10 μm (manufactured by Furukawa Electric Co., Ltd., NC-WS) using an automatic coating apparatus, and dried at 70 ° C, and subjected to a thickening procedure by punching. A negative electrode for a lithium ion battery is manufactured.

(iii) Characteristic evaluation

Cut the lithium ion battery negative electrode into 20 mm, and a metal Li was used for the counter electrode and the reference electrode, and an electrolytic solution composed of a mixed solution of ethylene carbonate and ethyl carbonate containing 1 mol/L of LiPF _{6 was} injected to constitute an electrochemical test unit. Further, the assembly of the electrochemical test unit was carried out in a hand-held work box having a dew point of -60 ° C or less. The evaluation of the charge and discharge characteristics was carried out by measuring the initial discharge capacity and the discharge capacity after charging and discharging for 50 cycles, and calculating the retention rate of the discharge capacity. The discharge capacity was calculated based on the total weight of the active material Si which is effective for the adsorption and release of lithium. First, charging was performed under a constant current condition of a current value of 0.1 C in an environment of 25 ° C, and charging was stopped when the voltage value was lowered to 0.02 V (the oxidation-reduction potential of the reference Li/Li+ was 0 V). Next, under the condition of a current value of 0.1 C, the discharge was performed until the voltage with respect to the reference electrode was 1.5 V, and the 0.1 C initial-base discharge capacity was measured. In addition, the 0.1C system can fully charge the current value for 10 hours. Next, the above charge and discharge were repeated for 50 cycles at a charge discharge rate of 0.1C. The ratio of the discharge capacity to the initial discharge capacity at the time of repeating 50 cycles of charge and discharge was determined as a percentage, and the discharge capacity retention ratio after 50 cycles was obtained.

[Embodiment 2]

The following description of porous tantalum composite particles containing complex elements Example 2.

(Example 2-1)

Yttrium powder (blocky purity: 95.0% or more), iron powder (granular: 2 mm, purity: 99.999% or more) and magnesium powder (in terms of Si:Fe:Mg=25:5:70 (atomic %)) Powder purity: 98.0% or more), and it was dissolved at 1,120 ° C in an argon atmosphere. Then, it was rapidly cooled at a cooling rate of 800 K/s using a single roll casting machine to prepare a bismuth alloy ribbon having a thickness of 40 μm (step (a)). The niobium alloy ribbon was immersed in a mash melt at 500 ° C for 1 minute, and immediately quenched in argon gas. By this treatment, a composite of cerium fine particles, a compound particle composed of a Si-Fe alloy, and a second phase composed of a Mg-Bi alloy or Bi (step (b)) is obtained. The composite was immersed in a 20% aqueous solution of nitric acid for 5 minutes to obtain porous ruthenium composite particles (step (c)).

(Examples 2-2 to 2-8, 2-10, 2-11)

The manufacturing conditions of the respective examples and comparative examples are summarized in Table 6. Examples 2-2 to 2-8, 2-10, and 2-11 are the same as those of the method of Example 2-1 except for the production conditions of the intermediate alloy elements shown in Table 6, the blending ratio of each element, and the like. Porous cerium composite particles were obtained. Further, in Example 2-4, the continuous strip-shaped niobium alloy could not be formed and was cut at 1 to 2 cm, so that it was a foil-like niobium alloy. In the linear tantalum intermediate alloy of Examples 2-5 100 μm means that the linear intermediate alloy diameter is 100 μm. The same applies to Examples 2-8.

(Examples 2-9)

The tantalum powder, vanadium powder and phosphorus powder were blended in a ratio of Si:V:P=40:1:59 (atomic %), and dissolved in an argon atmosphere at 1439 °C. Then, using a gas atomizing device, it was quenched at a cooling rate of 800 K/s to prepare a granular niobium alloy having a thickness of 40 μm (step (a)). The granulated niobium alloy was immersed in a cadmium melt at 750 ° C for 1 minute, and immediately quenched in argon gas. By this treatment, a composite of ruthenium fine particles, ruthenium compound particles composed of an alloy of Si and V, and a second phase composed of a P-Cd alloy or Cd is obtained (step (b)). The composite was immersed in a 20% aqueous solution of nitric acid for 5 minutes to obtain porous ruthenium composite particles (step (c)). Also, in the granular intermediate alloy 40 μm means that the average intermediate diameter of the granular intermediate alloy is 40 μm.

(Examples 2-12)

Niobium and magnesium were blended in a ratio of Si:Mg = 31:69 (atomic %), and dissolved in an argon atmosphere. Then, it was cooled in a mold, and an ingot made of a 5 mm square bismuth alloy was produced. The niobium alloy ingot was immersed in a ruthenium-containing melt containing 1 atom% of arsenic for 1 minute, and immediately quenched in argon gas. By this treatment, a composite of ruthenium fine particles, ruthenium compound particles composed of a Si-As alloy, and a second phase composed of a Mg-Bi alloy and Bi is obtained. The composite was immersed in a 20% aqueous solution of nitric acid for 50 minutes to obtain porous ruthenium composite particles.

(Examples 2-13 to 2-16)

In the examples 2-13 to 2-16, the porous ruthenium complex particles were obtained in the same manner as in the method of Example 2-12 except that the intermediate alloy elements shown in Table 6 and the blending ratio of each element were used. Further, Examples 2-13, 2-15, and 2-16 used a water-cooled block to increase the cooling rate.

(Comparative Example 2-1)

The tantalum powder, iron powder and magnesium powder were blended in a ratio of Si:Fe:Mg = 55:1:44 (atomic %), and the mixture was dissolved at 1,195 ° C in a vacuum oven. Then, it was cast using a copper block, and a 5 mm square bismuth alloy block was produced at a cooling rate of 1 K/s. The niobium alloy agglomerate was immersed in a 930 ° C crucible melt for 200 minutes and then immediately quenched in argon. The 2-phase composite was immersed in a 20% aqueous solution of nitric acid for 50 minutes. This comparative example does not satisfy a ÷ (a + Y) × 100 ≦ [maximum content of Si] of the formula (2).

(Comparative Example 2-2)

The tantalum powder, iron powder and magnesium powder were blended in a ratio of Si:Fe:Mg=25:11:64 (atomic %), and dissolved in a vacuum oven at 1105 °C. Then, it was cast using a copper block, and a 5 mm square bismuth alloy block was produced at a cooling rate of 1 K/s. The niobium alloy agglomerate was immersed in a crucible melt at 410 ° C for 10 minutes, and then immediately quenched in argon gas. The 2-phase composite was immersed in a 20% aqueous solution of nitric acid for 50 minutes. This comparative example does not satisfy 10≦a÷(a+Y)×100 of the formula (2).

(Comparative Example 2-3)

The cerium powder and the magnesium powder were blended in a ratio of Si:Mg = 24:76 (atomic %), and dissolved in a vacuum oven at 1095 °C. Then, it was cast using a water-cooled copper block, and a 300 μm bismuth alloy ribbon was produced at a cooling rate of 800 K/s. The niobium alloy ribbon was immersed in an alloy bath of 85 atomic percent of molten metal at 895 ° C and 15 atomic percent of nickel for 250 minutes, and immediately quenched in argon. The 2-phase composite was immersed in a 20% aqueous solution of nitric acid for 50 minutes. The concentration of the individual composite elements in the alloy bath of this comparative example exceeded 10 atom%.

(Comparative Example 2-4)

The tantalum powder and iron powder were blended in a ratio of Si:Fe = 90:10 (atomic %), and dissolved in a vacuum oven at 1390 °C. Then, using single roll casting The machine was quenched at a cooling rate of 110 K/s and a crucible alloy foil was produced. The niobium alloy foil was immersed in fluoronitric acid for 10 minutes and then washed with water.

(Comparative Example 2-5)

The cerium powder and the iron powder were blended in a ratio of Si:Fe = 66:34 (atomic %), and dissolved in a vacuum oven at 1,250 °C. Then, it was subjected to rapid solidification by a gas atomizing device, and an FeSi ₂ intermetallic compound was produced. This was placed on a sieve to recover particles having an average particle diameter of 1 to 10 μm. The particles and the cerium particles having an average particle diameter of 5 μm (SIE23PB, manufactured by High Purity Chemical Research Laboratory Co., Ltd.) were mixed at 2:1, and styrene-butadiene rubber (SBR) was used as a binder to granulate.

[Evaluation]

The evaluation results are summarized in Table 7. Further, in Examples 2-13 to 2-16 and Comparative Example 2-3, since the ruthenium particles were large, the particles which were pulverized and reduced in the mortar were used for the property evaluation. For example, the average particle size of the porous tantalum composite particles of Examples 2-13 is 130 The reason of 33 is to pulverize the porous ruthenium complex particles having an average particle diameter of 130 μm and obtain porous ruthenium complex particles having an average particle diameter of 33 μm.

As shown in Table 7, the average particle diameter x of the fine particles of each example is 2 nm to 2 μm, and the standard deviation σ of the particle diameter of the fine particles is 1 to 500 nm, and the ratio of the average x to the standard deviation σ (σ/x). It is 0.01 to 0.5. Further, in each of the examples, the ratio (a/b) of the average longest diameter a to the average shortest diameter b is 1.1 to 50. Further, the ratio of the thickness of the connection portion between the fine particles and the adjacent fine particles to the diameter of the fine particles larger than the adjacent fine particles (the thickness ratio of the joint) is 80% or less.

In each of the examples, the porous tantalum composite particles satisfying the requirements of the ninth application of the patent application range are produced by a manufacturing method using de- ing-de- ing (dealloying), and thus 50 in each embodiment. The capacity retention rate after the cycle is high and the cycle characteristics are good. Since the particle size of the ruthenium particles is uniform, no stress is concentrated on the uneven portion of the particle size during expansion and contraction of the active material during charge and discharge, and therefore it is estimated that the cycle characteristics are greatly improved.

Since the capacity retention rate after 50 cycles of each embodiment is higher than that of the respective comparative examples, and the ratio of the discharge capacity reduction due to the reverse charge and discharge is small, it is expected that the life of the battery is long.

Further, in each of the examples, the negative electrode active material is a porous tantalum composite particle having a three-dimensional network structure or a continuous void, and therefore, even if alloying and de-alloying of Li and Si occur during charging and discharging, expansion and contraction are caused. The volume change does not cause cracking or micronization of the ruthenium composite particles, and the discharge capacity retention rate is high.

In a more detailed comparison, in Comparative Example 2-1, pure Si crystal was used as the primary crystal in the preparation of the intermediate alloy, and a eutectic structure (Si and Mg ₂ Si) was further formed at the end of solidification. The primary crystal system is coarsened to about 10 μm. The primary Si does not become finer even if it is immersed in the cerium melt, and remains in the original shape even after the etching step. Therefore, when Li repeatedly invades and releases, the Si monomer including coarse Si cannot be combined with the volume change of expansion and contraction caused by alloying and de-alloying of Li and Si, causing cracking or collapse, and loss of set. The ratio of the electrical path or the electrode function becomes large, and it can be considered that the battery life is shortened.

In Comparative Example 2-2, the composite element had a large amount of iron and formed a large amount of telluride as compared with ruthenium, so that the discharge capacity was small.

In Comparative Example 2-3, the amount of Ni added to the composite element in the molten metal was large, and a large amount of telluride was formed, so that the discharge capacity was small.

Fig. 24 is a SEM photograph of the surface of the porous cerium particles of Comparative Example 2-4. Most particles having a particle size of 1 to 2 μm were observed.

In Comparative Example 2-4, since the pore structure was formed by etching with hydrofluoric acid or nitric acid, a place where pores were not formed was formed in the center portion of the particle. The part of the core cannot be matched with the volume change of charge and discharge, and it is considered that the cycle characteristics are poor.

In Comparative Example 2-5, since only the ruthenium particles having no pore structure were formed, the volume change of charge and discharge could not be matched, and it was considered that the cycle characteristics were poor.

(Evaluation of particle shape)

The particle shape of the porous tantalum composite particles was observed using a transmission electron microscope (JEM 3100FEF manufactured by JEOL Ltd.). An SEM photograph of the particles of Example 2-1 is shown in Fig. 14, and an SEM photograph of the inside of the particle of Example 2-1 is shown in Fig. 15, and the surface of the particle of Example 2-1 is shown in Fig. 16. SEM photo. In Fig. 14 and Fig. 15, a particle size of 20 nm was observed to The fine particles of 50 nm are bonded to each other and aggregated in a large amount, and porous ruthenium complex particles are formed. Further, in Fig. 14 and Fig. 15, it was observed that there was no large difference in the void ratio or the particle diameter of the fine particles. In Fig. 16, it was observed that the small ruthenium particles were bonded to the particles of the large ruthenium compound.

Fig. 17 is an X-ray diffraction grating image constituting the fine particles of the ruthenium composite particles. It is observed that the ruthenium microcrystals are single crystals from the point where the crystals of ruthenium are produced.

The average particle size of the bismuth microparticles is measured by image information of an electron microscope (SEM). The porous tantalum composite particles are divided into a region near the surface in the radial direction of 50% or more and an inner region of the particles in the radial direction within 50%, and each of the average particle diameters Ds and Di is obtained from each SEM photograph, and the calculation is performed. Wait for the ratio of Ds to Di. In the embodiment, the value of Ds/Di is between 0.5 and 1.5, but in Comparative Example 2-4 obtained by the etching method, the average particle diameter of the microparticles in the vicinity of the surface is small as compared with the inner region of the particle, and The value of Ds/Di becomes smaller. The average particle diameter of the porous cerium composite particles was measured by using the aforementioned SEM observation and DLS.

The Si concentration of the fine particles and the concentration of Si and the composite element of the porous tantalum composite particles are measured by an ICP emission spectrometer. In either embodiment, the ruthenium microparticles contain 矽80 at% or more.

The average void ratio of the porous tantalum composite particles was measured by a mercury intrusion method (JIS R 1655) using a 15 mL unit.

Further, the porous tantalum composite particles are divided into a region near the surface in the radial direction of 50% or more and an inner region of the particles having a radius of 50% or less, and any of the regions are observed by a surface scanning electron microscope. Square, and Xs and Xi of each average void ratio are obtained, and the ratio of Xs to Xi is calculated. In the examples, the value of Xs/Xi is between 0.5 and 1.5, but in Comparative Example 2-4 obtained by the etching method, the pore structure in the vicinity of the surface is developed in comparison with the internal region of the particle, so Xs/Xi The value becomes larger.

(Evaluation of cycle characteristics when particles are used for the negative electrode)

The cycle characteristics were evaluated in the same manner as in Example 1 except that the discharge capacity was calculated based on the total weight of the bismuth compound and the active material Si which was adsorbed and released.

[Example 3] (Example 3-1)

The conditions of the steps (a) to (c) were changed using the same procedure as in Example 1, and the particle size, shape, and distribution of the bismuth alloy fine particles were changed. The immersion temperature and time in the step (b) are specifically changed. Further, mechanical stirring (stirring energy) or vibration (amplitude: 1 mm × 60 Hz) was applied to the molten metal bath of the step (b). These conditions are shown in Table 8. Further, the results of evaluation of the porous tantalum particles and the fine particles obtained by the production method in the same manner as in Example 1 are shown in Table 9.

The capacity retention ratio was less than 80% after 50 cycles in each of the comparative examples, and the capacity retention ratio after 50 cycles was more than 80% in each of the examples.

The average particle diameter x of the fine particles of each of the examples is 2 nm to 2 μm, and the standard deviation σ of the particle diameter of the fine particles is 1 to 500 nm, and the ratio (σ/x) of the average x to the standard deviation σ is 0.01 to 0.5. Further, in each of the examples, the ratio (a/b) of the average longest diameter a to the average shortest diameter b is 1.1 to 50. Further, the ratio of the thickness of the connection portion between the fine particles and the adjacent fine particles to the diameter of the fine particles larger than the adjacent fine particles (the thickness ratio of the joint) is 80% or less.

Figure 18 is a SEM photograph of porous cerium particles of Example 3-7. It can be understood that the fine particles of about 30 nm in diameter are mostly aggregated.

Further, Fig. 19 is a TEM photograph of ruthenium fine particles constituting the porous ruthenium particles of Example 3-7. The average particle diameter x of the fine particles was 28.6 nm, the standard deviation σ was 5.3 nm, and σ/x = 0.19. It can be understood that the particle size is uniform, and the yttrium particles are joined by a coarse joint.

Figure 20 is a particle size distribution of the fine particles of the porous tantalum particles of Examples 3-7. One by one, the microparticles are flat spherical particles, and the particles are joined to form, so it is understood that the distribution is not a regular distribution.

Fig. 21 is a TEM photograph of the ruthenium microparticles constituting the porous ruthenium particles of Example 3-8, and the upper left is a limited-field electron beam diffraction image in the observation region by the TEM. In the TEM photograph, it is understood that there is no grain boundary in a ruthenium particle and it is a single crystal. Further, it has been observed that in the limited-view electron beam diffraction image, it is understood that the ruthenium microparticle is still a single crystal. Further, the fine particles of the crucible have a flat spherical shape, a major axis diameter of 36 nm, and a short axis diameter of 27 nm. In addition, taking the average of most of the fine particles, The average shortest diameter a is 36 nm, the average shortest diameter b is 27 nm, and a/b = 1.33.

Figure 25 is a SEM photograph of porous cerium particles of Example 3-1. Most of the fine particles that grew into a polygonal column were observed. The average pillar diameter x is 203.6 nm, the standard deviation σ is 80.6 nm, and σ/x is 0.40.

Figure 26 is a SEM photograph of the porous ruthenium particles of Example 3-2. A large number of fine particles having a pillar diameter of about 20 nm and growing into a polygonal column shape were observed.

Figure 27 is a SEM photograph of the porous ruthenium particles of Example 3-3. Most of the fine particles that have grown substantially are observed. The average particle diameter x is 694.0 nm, the standard deviation σ is 231.7 nm, and σ/x is 0.33. Further, since the immersion of the ruthenium alloy surface on the surface of the ruthenium alloy was large due to immersion for a long period of time, the ratio of Es/Ei was 1.08.

Figure 28 is a photograph of the microstructure of the intermediate alloy of Examples 1-15.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the invention is not limited thereto. It is to be understood that various modifications and changes can be made in the technical scope of the present disclosure as long as they are the ones of ordinary skill in the art, and such variations or modifications are of course Technical scope.

Industrial availability

The porous tantalum composite particles of the present invention can be used not only as a negative electrode of a lithium ion battery but also as a negative electrode of a lithium ion capacitor, a solar cell, a light-emitting material, and a material for filtration.

1‧‧‧Porous porous particles

I‧‧‧particle interior area

3‧‧‧矽Microparticles

S‧‧‧ Area near the surface

Claims (18)

A porous ruthenium particle having a plurality of ruthenium microparticles joined to each other and having a continuous void, wherein the particle diameter of the ruthenium microparticles, the pillar diameter or the average x of the pillar side is 2 nm to 2 μm, and the particle size of the ruthenium microparticles and the pillar The standard deviation σ of the diameter or the pillar side is 1 to 500 nm, and the ratio (σ/x) of the aforementioned average x to the aforementioned standard deviation σ is 0.01 to 0.5. The porous tantalum particle according to claim 1, wherein the shape of the tantalum fine particles has a flat spherical shape, a cylindrical shape or a polygonal column shape, and an average longest diameter or a ratio of the longest side a to the average shortest diameter or the shortest side b ( a/b) is from 1.1 to 50. The porous tantalum particle according to the first aspect of the invention, wherein the porous niobium particles have an average particle diameter of 0.1 μm to 1000 μm, and the porous niobium particles have an average void ratio of 15 to 93%; The average particle diameter Ds of the ruthenium particles in the vicinity of the surface of the ruthenium particle in the radial direction of 50% or more, and the average particle diameter of the ruthenium particles in the internal region of the particle within 50% of the radius of the porous ruthenium particle a ratio of Di of Ds/Di of 0.5 to 1.5; and a porosity Xs of a region near the surface of the porous cerium particle which is 50% or more in the radial direction, and a particle of 50% or less in the radial direction of the porous cerium particle The ratio of the void ratio Xi of the inner region is Xs/Xi of 0.5 to 1.5; Further, 矽80 atom% or more is contained in a ratio of elements other than oxygen. The porous tantalum particle according to the first aspect of the invention, wherein the porous tantalum particle is divided into a region S near the surface in the radial direction of 90% or more, and an inner region I of the particle in the radial direction of 90% or less. The average particle diameter of the fine particles of the surface in the vicinity of the surface S is Es, and when the average particle diameter of the fine particles of the fine particles constituting the internal region I of the particle is Ei, Es/Ei is 0.01 to 1.0. The porous tantalum particles according to the first aspect of the invention, wherein the fine particles of the fine particles are solid fine particles, and are characterized by containing 原子80 atom% or more in a ratio of elements other than oxygen. The porous tantalum particles according to claim 1, wherein the area of the joint between the fine particles of the fine particles is 30% or less of the surface area of the fine particles. The porous tantalum particle according to claim 1, wherein in the joint portion of the tantalum fine particles and the adjacent fine particles, the thickness or diameter of the joint portion is larger than the diameter of the fine particles of the adjacent fine particles. % or less, and the joint portion is composed of a crystalline ruthenium or osmium oxide. In the porous ruthenium particles of claim 2, most of the ruthenium microparticles are oriented, and the long axis directions of most of the ruthenium microparticles are within ±30° of a certain direction. A porous ruthenium composite particle, which is characterized in that a plurality of ruthenium particles are joined to a plurality of ruthenium compound particles and have continuous voids, and are characterized by: The ruthenium compound particles comprise ruthenium and are selected from the group consisting of As, Ba, Ca, Ce, Co, Cr, Cu, Er, Fe, Gd, Hf, Lu, Mg, Mn, Mo, Nb, Nd, Ni, Os, a complex of one or more of the group consisting of Pr, Pt, Pu, Re, Rh, Ru, Sc, Sm, Sr, Ta, Te, Th, Ti, Tm, U, V, W, Y, Yb, and Zr a compound of an element; and an average x of the particle diameter of the ruthenium particle, a pillar diameter or a pillar edge of 2 nm to 2 μm, a particle diameter of the ruthenium microparticle, a standard deviation of a pillar diameter or a pillar edge σ of 1 to 500 nm, and an average of x The ratio (σ/x) to the aforementioned standard deviation σ is 0.01 to 0.5. The porous tantalum composite particle according to claim 9, wherein the shape of the tantalum fine particles has a flat spherical shape, a cylindrical shape or a polygonal column shape, and an average longest diameter or a longest side a and an average shortest diameter or a shortest side b The ratio (a/b) is 1.1 to 50. The porous tantalum composite particles according to claim 9, wherein the porous tantalum composite particles have an average particle diameter of 0.1 μm to 1000 μm. The porous ruthenium complex particles according to claim 9, wherein the ruthenium fine particles contain 矽80 atom% or more of solid ruthenium fine particles in a ratio of elements other than oxygen. The porous ruthenium complex particles according to claim 9, wherein the ruthenium compound particles have an average particle diameter of 50 nm to 50 μm, and the ruthenium compound particles are characterized by containing 50 to 90 at a ratio of elements other than oxygen. A solid bismuth compound particle with an atomic %. The porous tantalum composite particle according to the ninth aspect of the invention, wherein the porous niobium composite particles have an average particle diameter Ds of the niobium fine particles in a region near the surface of 50% or more in the radial direction, and the porous crucible The ratio Ds/Di of the average particle diameter Di of the above-mentioned cerium fine particles in the inner region of the particles within 50% of the composite particles in the radial direction is 0.5 to 1.5. The porous tantalum composite particle according to the ninth aspect of the invention, wherein the void ratio Xs of the region near the surface of the porous tantalum composite particle in the radial direction of 50% or more is in contact with the porous tantalum composite particle. The ratio of the void ratio Xi of the inner region of the particles within 50% in the radial direction is Xs/Xi of 0.5 to 1.5. The porous tantalum composite particle according to the ninth aspect of the invention, wherein the porous tantalum composite particle is divided into a surface vicinity region S in the radial direction of 90% or more and an internal region I of the particle in the radial direction of 90% or less. Further, when the average particle diameter of the fine particles of the fine particles constituting the surface vicinity S is Es, and the average particle diameter of the fine particles of the fine particles constituting the internal region I of the particles is Ei, Es/Ei is 0.01 to 1.0. The porous tantalum composite particle according to claim 9, wherein in the joint portion of the tantalum fine particles and the adjacent fine particles, the thickness or diameter of the joint portion is larger than the diameter of the adjacent fine particles. 80% or less, and the joint portion is composed of a crystalline niobium or tantalum oxide. The porous tantalum composite particles according to claim 10, wherein the plurality of the fine particles of the tantalum are oriented, and the long axis direction of the plurality of the fine particles is ±30° in a certain direction. Within.