CN104125927B

CN104125927B - Porous silicon particle and Porous silicon complex particles

Info

Publication number: CN104125927B
Application number: CN201380010929.6A
Authority: CN
Inventors: 吉田浩一; 濑川春彦; 谷俊夫; 西村健; 加藤秀实; 和田武
Original assignee: Furukawa Electric Co Ltd; Tohoku Techno Arch Co Ltd
Current assignee: Furukawa Electric Co Ltd; Tohoku Techno Arch Co Ltd
Priority date: 2012-03-21
Filing date: 2013-03-19
Publication date: 2016-05-25
Anticipated expiration: 2033-03-19
Also published as: CN104125927A; JP5830419B2; WO2013141230A1; TWI601690B; TW201343549A; JP2013193933A; KR101625779B1; KR20140103175A

Abstract

The object of the invention is to, obtain the Porous silicon particle and the Porous silicon complex particles that are suitable for realizing negative material that the lithium ion battery of high power capacity and good cycle characteristics uses etc. As its solution, the present invention uses following Porous silicon particle, it is the Porous silicon particle (1) multiple silicon particles (3) joint to continuous space, it is characterized in that, the average x of the particle diameter of described silicon particle or strut diameter is 2nm～2 μ m, the particle diameter of described silicon particle or the standard deviation of strut diameter are 1～500nm, and (σ/x) is 0.01～0.5 for the ratio of described average x and described standard deviation. In addition, also can use following Porous silicon complex particles, it is multiple silicon particles are engaged with multiple silicon compound particles and have the Porous silicon complex particles in continuous space, it is characterized in that possessing same feature.

Description

Porous silicon particle and Porous silicon complex particles

Technical field

Porous silicon particle used in the negative pole that the present invention relates to use at lithium ion battery etc. Porous silicon of the present inventionParticle can be in capacitor, lithium-ion capacitor, silicon for solar cell semiconductor.

Background technology

In the past, used native graphite, Delanium, amorphous carbon, mesocarbon etc. various as negative electrode active materialThe lithium ion battery of carbon-based material or lithium titanate, ashbury metal etc. has obtained practical. In addition, also carry out following operation,,, by mixing the adhesive of the conductive auxiliary agent such as negative electrode active material, carbon black and resin and prepare slurry, be coated on Copper Foil and dryDry, form negative pole.

On the other hand, taking high capacity as object, developed metal large theoretical capacity as lithium compoundOr the negative pole used of lithium ion battery that uses as negative electrode active material of alloy, particularly silicon and alloy thereof. But, owing to inhaling storageSilicon volumetric expansion with respect to the silicon of inhaling before storage of lithium ion to about 4 times, therefore silicon is made as negative electrode active materialWith negative pole can repeatedly expand and shrink when the charge and discharge cycles. Thus, can produce peeling off of negative electrode active material etc., with in the pastThe carbon that comprises be that the negative pole of active material is compared, have extremely short problem of life-span.

As the manufacture method in the past of negative pole that has used silicon, known have a following technology, that is, and and by silicon mechanical crushing extremelyNumber micron-scale, uses (for example, with reference to patent literary composition with negative material as lithium battery by coating conductive material on itOffer 1).

In addition, as the manufacture method in the past of negative pole that has used silicon, also have following method etc., that is, and to silicon substrateImplement anodic oxidation and form the grooves such as slit, the bulk metal crystallization of (ribbon) shape that makes strip goes out (for example reference of fine siliconPatent documentation 2).

In addition, also known have a following technology,, piles up polystyrene, PMMA etc. high molecular on conductive board that isParticle, utilizing plating to apply after the metal with lithium alloyage on it, makes metal by removing high molecular particlePorous body (porous plastid) (for example, with reference to patent documentation 3).

And then also known have a following technology, that is, will be equivalent to the Si intermediate alloy of operation thing in the middle of of the present inventionMaterial use (for example, with reference to patent documentation 4,5) as negative material for lithium battery.

In addition, also known have a following technology, that is, it is heat-treated and is used as lithium battery negative material(for example, with reference to patent documentation 6).

In addition, about this technology, known have a following technology, that is, and and from Si and the element M of application quench solidification fabrication techniquesSi alloy in, utilize acid or alkali fully stripping of element M to be removed to (for example, with reference to patent documentation 7).

And then also known have the technology of utilizing hydrofluoric acid, nitric acid to come etching metal silicon or silicon alloy (for example, with reference to patent literary compositionOffer 8,9,10).

Prior art document

Patent documentation

Patent documentation 1: No. 4172443 communiques of Japan Patent

Patent documentation 2: TOHKEMY 2008-135364 communique

Patent documentation 3: TOHKEMY 2006-260886 communique

Patent documentation 4: TOHKEMY 2000-149937 communique

Patent documentation 5: TOHKEMY 2004-362895 communique

Patent documentation 6: TOHKEMY 2009-032644 communique

Patent documentation 7: No. 3827642 communique of Japan Patent

Patent documentation 8: U. S. application discloses description No. 2006/0251561

Patent documentation 9: U. S. application discloses description No. 2009/0186267

Patent documentation 10: U. S. application discloses description No. 2012/0129049

Summary of the invention

Invent problem to be solved

But the technology of patent documentation 1 is by the monocrystalline of several micron-scales and the atom of silicon of pulverizing monocrystalline silicon and obtainThere is the plate of stratiform or three-dimensional mesh structure or the technology that powder uses as negative pole active material. And then, lead in order to giveElectrically, use silicon compound (by silicon carbide, silicon cyanide, silicon nitride, Si oxide, silicon boride, silicon boron oxide compound,The silication that silicon boron nitride, silicon-oxygen nitride, silicon alkali metal alloy, silicon alkaline-earth metal alloy, silicon transition metal alloy formMore than one in the middle of compound group). But, because the Volume Changes of silicon in the time discharging and recharging is large, therefore in patent documentation 1, recordNegative electrode active material can produce the tortoise of the peeling off of the micronizing of negative electrode active material and negative electrode active material, negative pole in the time discharging and rechargingSplit, the reduction of electric conductivity between negative electrode active material etc., make volume lowering. Therefore, have that cycle characteristics is poor, secondary cellShort problem of life-span. Particularly, be expected to that the Volume Changes when discharging and recharging is large as the practical silicon of negative material, thereforeEasily produce and break, have the poor problem of charge/discharge cycle characteristics.

In addition, the technology of patent documentation 2 be coating negative electrode active material, conductive auxiliary agent and adhesive slurry and dry andForm negative pole. This kind negative pole is in the past bonding with the adhesive of the low resin of electric conductivity to negative electrode active material and collector body, forDo not make internal electrical resistive large, the use amount of resin need to be restricted to Min., thereby a little less than adhesion. Because silicon is charging and dischargingVolume Changes when electricity is large, and therefore, in the technology of patent documentation 2, negative electrode active material can produce negative electrode active in the time discharging and rechargingReduction of electric conductivity between be full of cracks, the negative electrode active material of the peeling off of the micronizing of material and negative electrode active material, negative pole etc., makesObtain volume lowering. Therefore, there is the problem that cycle characteristics is poor, the life-span of secondary cell is short.

In addition, the technology of patent documentation 3 is piled up the high molecular particle such as polystyrene or PMMA on conductive board, toOn it, utilize plating to apply after the metal with lithium alloyage, can produce the porous body of metal by removing high molecular particle(porous plastid). But, aspect the porous body of making Si, on the high molecular particle such as polystyrene or PMMA, plate Si veryDifficulty, thereby have the problem that cannot adapt to industrial.

In addition, the technology of patent documentation 4 is to manufacture the method for negative electrode material for nonaqueous electrode secondary battery, and its feature existsIn, comprise following operation, that is, and by form alloy particle raw material fused mass so that setting rate be 100 DEG C/sec aboveMode is cooling and solidify, and forms and contains Si grain and the solid solution that contains Si or intermetallic that it is surrounded at least partly mutuallyThe alloy of the phase of thing. But, with regard to the aspect that the method is reacted with regard to Li, the solid solution that contains Si that need to surroundInterior diffusion is moved, thereby lacks reactivity, and the content of the Si that can participate in discharging and recharging is few, considers also not reach from this pointTo practical.

In addition, the technology utilization of patent documentation 5 contains silicon (containing ratio of silicon is that the above 60 quality % of 22 quality % are following)Form with the silicon alloy powder of any one kind or two or more metallic element of copper, nickel and cobalt. By utilized single-roller method orAtomization synthesizes, and the micronizing of Volume Changes due to suppressing to store/emit based on the suction of lithium ion etc. But, the methodIn with regard to the aspect of reacting with regard to Li, need in the solid solution that contains Si surrounding, spread mobilely, thereby lack anti-Ying Xing, and the content of the Si that can participate in discharging and recharging is few, considers also not reach practical from this point.

In addition, the technology of patent documentation 6 comprises: will comprise Si and be selected from Co, Ni, Ag, Sn, Al, Fe, Zr, Cr, Cu, P,The alloy molten solution chilling of the one kind or two or more element in Bi, V, Mn, Nb, Mo, In and rare earth element, obtains Si base without fixedThe operation of shape alloy; And the operation that the Si base amorphous alloy of gained is heat-treated. By to Si base amorphous alloyHeat-treat, and separate out the fine crystalline Si core about tens of nm～300nm. But, in the method, carry out with regard to LiThe aspect of reaction need to spread and move in the solid solution that contains Si surrounding, thereby lacks reactivity, Er QiekeThe content of the Si discharging and recharging with participation is few, considers also not reach practical from this point.

In addition, the technology of patent documentation 7 is the technology while being adapted to manufacture amorphous thin band or micropowder etc., is only coldBut speed is 10⁴The technology that makes it to solidify when K/ second is above. In the solidifying of common alloy, be formed on 1 dendritic growthSimultaneously also the grow ingotism of 2 dendrite. In special alloy system (Cu-Mg system, Ni-Ti system etc.), 10⁴K/ secondWhen above, can form amorphous metal, but for example, in other system (Si-Ni system), even if in cooling velocity be only10⁴When K/ second is above, make it to solidify, also cannot obtain amorphous metal, but form crystalline phase. Crystal while forming this crystalline phaseSize is according to cooling velocity (R:K/ second) and dendritic arm spacing (relation m) of DAS: μ and determining.

DAS＝A×R^B(in general, A:40～100, B:-0.3～-0.4)

Thus, in the situation that thering is crystalline phase, for example, the in the situation that of A:60, B:-0.35, be 10 at R⁴DAS when K/ secondBe 1 μ m. Crystalline phase also according to be this size, thereby cannot obtain the fine crystalline phase of 10nm etc. Based on these reasons,In the materials such as Si-Ni system, utilize separately this quench solidification technology cannot obtain the Porous being formed by fine crystalline phase.

In addition, the technology of patent documentation 8,9 is to use hydrofluoric acid, nitric acid etch metallic silicon and make fine sky on surfaceThe technology in hole. But, be 140～400m from BET specific area²The viewpoint of/g and the response that discharges and recharges is considered, exists and doesSufficient not problem for Si negative pole is used active material. In addition, utilize the emptying aperture that etching forms not disperse equably, fromParticle surface is not to center emptying aperture equably. Thus, the volumetric expansion being accompanied by while discharging and recharging is shunk, in particlePortion's micronizing aggravation, thereby have short problem of life-span.

In addition, the technology of patent documentation 10 is by the silicon alloy of molten condition (aluminium alloy that contains silicon) quench solidificationAfterwards, use hydrofluoric acid or nitric acid etch and reclaim the technology of fine silicon particle. This technology by use hypereutectic composition andWhile solidifying, preferentially crystallization goes out silicon particle, by increase cooling velocity (100K/s) can in alloy, make fine granular/Tabular primary silicon. In addition, remaining have Al-Si eutectic structure in the situation that in interdendritic in the middle of crystalline growth, thereafterIn etch processes, also can produce the situation that forms space (porous). But, in this quench solidification, consider to make from mechanismThere is the spongiform silicon of common continuous structure.

The present invention completes in view of described problem, and its object is, obtains and is suitable for realizing high power capacity and goodThe Porous silicon particle of the negative material that the lithium ion battery of cycle characteristics is used etc.

For the scheme of dealing with problems

The inventor conducts in-depth research in order to reach above-mentioned purpose, found that, utilize silicon alloy from phase decomposition(separating out of the silicon in the liquation from silicon alloy) and dealloying (dealloying), can obtain fine PorousSilicon. Because separating out of the silicon in the liquation from silicon alloy is to carry out in the motlten metal of high temperature, therefore de-in utilizationThe skin section of the Porous silicon particle that composition corrosion (dealloying) obtains and inside are difficult to produce large aspect primary particle sizeDistribution. This is the diffusion using motlten metal as solvent, when the atom being removed in silicon alloy is during by solvent atomic substitutions,Will discharge from diffuse interface immediately because of the convection current in solvent etc., always there is the melting gold of given composition in diffuse interfaceBelong to, thereby have certain concentration gradient. Thus, because the diffusion in silicon alloy is carried out with certain speed, therefore can be withCertain speed is supplied with the silicon atom participating in from phase decomposition, so the constant dimension of silicon particle.

And then, in the Porous silicon particle that utilizes above-mentioned method for making to obtain, aspect voidage, be difficult to produce large distribution.On the other hand, for example, in the etching by sour, because inside particles exists restriction in the concentration proliferation of de-composition element,Therefore the porosity of particle skin section becomes large, and the porosity of inside particles diminishes. According to condition difference, exist at particle central partDo not have the core of leachy Si, when with the reacting of Li, produce micronizing, make cycle characteristics variation. The present invention is based on this opinionAnd the invention completing.

, provide following invention.

(1) a Porous silicon particle, is the Porous silicon particle multiple silicon particles joints to continuous space,It is characterized in that, described silicon particle be shaped as spherical or polygonal column, particle diameter, strut diameter or the pillar limit of described silicon particleAverage x be 2nm～2 μ m, the standard deviation on particle diameter, strut diameter or the pillar limit of described silicon particle is 1～500nm, described in(σ/x) is 0.01～0.5 for the ratio of average x and described standard deviation.

(2) according to the Porous silicon particle of recording in (1), it is characterized in that, the shape of described silicon particle has flatSpherical, cylindric or polygonal column, the ratio (a/b) of average longest diameter or longest edge a and average the shortest diameter or minor face b is1.1～50。

(3) according to the Porous silicon particle of recording in (1), it is characterized in that the average grain diameter of described Porous silicon particleBe 0.1 μ m～1000 μ m, the average void fraction of described Porous silicon particle is 15～93%, the radius of described Porous silicon particleHalf of the average grain diameter Ds of the described silicon particle in the near surface region in direction more than 50% and described Porous silicon particleIn the direction of footpath, the ratio Ds/Di of the 50% average grain diameter Di taking the described silicon particle in interior inside particles region is as 0.5～1.5,Voidage Xs near surface region on the radial direction of described Porous silicon particle more than 50% and described Porous siliconOn the radial direction of particle, the 50% ratio Xs/Xi taking the voidage Xi in interior inside particles region is as 0.5～1.5, with by oxygenExcept the ratiometer of element contain silicon more than 80 atom %.

(4) according to the Porous silicon particle of recording in (1), it is characterized in that, described Porous silicon particle is divided into radiusInside particles region I near surface region S in direction more than 90% and radial direction below 90%, will form instituteThe average grain diameter of stating the described silicon particle of near surface region S is made as Es, by micro-the described silicon that forms described inside particles region IWhen the average grain diameter of grain is made as Ei, Es/Ei is 0.01～1.0.

(5) according to the Porous silicon particle of recording in (1), it is characterized in that, described silicon particle is to be characterised in that with by oxygenExcept the ratiometer of the element solid silicon particle that contains silicon more than 80 atom %.

(6) according to the Porous silicon particle of recording in (1), it is characterized in that the area at the junction surface between described silicon particleFor below 30% of surface area of described silicon particle.

(7) according to the Porous silicon particle of recording in (1), it is characterized in that, at described silicon particle and adjacent described siliconIn the junction surface of particulate, the thickness at described junction surface or diameter are a larger side's of adjacent described silicon particle silicon particle straightBelow 80% of footpath, described junction surface is made up of crystallized silicon or Si oxide.

(8) according to the Porous silicon particle of recording in (2), it is characterized in that, multiple described silicon particles have produced orientation, manyThe direction of the major axis of individual described silicon particle all in certain direction ± 30 ° in.

(9) a Porous silicon complex particles is that multiple silicon particles are engaged and had with multiple silicon compound particlesThe Porous silicon complex particles in continuous space, is characterized in that, described silicon compound particle comprise silicon with select free As,Ba、Ca、Ce、Co、Cr、Cu、Er、Fe、Gd、Hf、Lu、Mg、Mn、Mo、Nb、Nd、Ni、Os、Pr、Pt、Pu、Re、Rh、Ru、Sc、The compound of the complex element of more than one of the group that Sm, Sr, Ta, Te, Th, Ti, Tm, U, V, W, Y, Yb, Zr form, described inThe average x on particle diameter, strut diameter or the pillar limit of silicon particle is 2nm～2 μ m, the particle diameter of described silicon particle, strut diameter orThe standard deviation on post limit is 1～500nm, and (σ/x) is 0.01～0.5 for the ratio of described average x and described standard deviation.

(10) according to the Porous silicon complex particles of recording in (9), it is characterized in that, the shape of described silicon particle hasFlat spherical, cylindric or polygonal column, the ratio of average longest diameter or longest edge a and average the shortest diameter or minor face b(a/b) be 1.1～50.

(11) according to the Porous silicon complex particles of recording in (9), it is characterized in that described Porous silicon complex grainThe average grain diameter of son is 0.1 μ m～1000 μ m.

(12) according to the Porous silicon complex particles of recording in (9), it is characterized in that, described silicon particle is so that oxygen is removedThe ratiometer of outer element contains the solid silicon particles of silicon more than 80 atom %.

(13) according to the Porous silicon complex particles of recording in (9), it is characterized in that described silicon compound particle flatAll particle diameter is 50nm～50 μ m, described silicon compound particle be characterised in that with the ratiometer of the element except oxygen contain 50～The particle of the solid silicon compound of the silicon of 90 atom %.

(14) according to the Porous silicon complex particles of recording in (9), it is characterized in that described Porous silicon complex grainThe average grain diameter Ds of the described silicon particle in the near surface region on the radial direction of son more than 50% and described Porous silicon are multipleOn the radial direction of fit particle the ratio Ds/Di of the average grain diameter Di of the 50% described silicon particle taking interior inside particles region as0.5～1.5。

(15) according to the Porous silicon complex particles of recording in (9), it is characterized in that described Porous silicon complex grainThe voidage Xs near surface region and the radius of described Porous silicon complex particles on the radial direction of son more than 50%In direction, the ratio Xs/Xi of the 50% voidage Xi taking interior inside particles region is as 0.5～1.5.

(16) according to the Porous silicon complex particles of recording in (9), it is characterized in that, by described Porous silicon complexParticle is divided on radial direction the inside particles region I below 90% on more than 90% near surface region S and radial direction,The average grain diameter of the described silicon particle that forms described near surface region S is being made as to Es, will forming described inside particles region IThe average grain diameter of described silicon particle while being made as Ei, Es/Ei is 0.01～1.0.

(17) according to the Porous silicon complex particles of recording in (9), it is characterized in that, at described silicon particle and adjacentIn the junction surface of described silicon particle, the thickness at described junction surface or radius are that a larger side's the silicon of adjacent described silicon particle is micro-Below 80% of radius of grain, described junction surface is made up of crystallized silicon or Si oxide.

(18) according to the Porous silicon complex particles of recording in (10), it is characterized in that, multiple described silicon particles produceOrientation, the direction of the major axis of multiple described silicon particles all in certain direction ± 30 ° in.

The effect of invention

According to the present invention, can obtain and be suitable for realizing the negative pole that the lithium ion battery of high power capacity and good cycle characteristics is usedThe Porous silicon particle of material etc.

Brief description of the drawings

Fig. 1 (a) is the figure that represents Porous silicon particle 1 of the present invention, is (b) to represent that the surface of Porous silicon particle 1 is attachedThe figure of near field S and inside particles region I.

Fig. 2 (a)～(c) is the figure that represents the summary of the manufacture method of Porous silicon particle 1.

Fig. 3 is the figure of the manufacturing process of explanation thin ribbon shaped silicon intermediate alloy of the present invention.

Fig. 4 is the figure of explanation thin ribbon shaped silicon intermediate alloy of the present invention to the dipping process in liquation element.

Fig. 5 (a) is the figure that represents gas atomization device 31 of the present invention, is (b) to represent rotating circular disk atomization of the present inventionThe figure of device 41.

Fig. 6 (a)～(c) is the figure of the manufacturing process of explanation bulk silicon intermediate alloy.

Fig. 7 (a), (b) are the figure that represents liquation immersion system of the present invention.

Fig. 8 (a) is the figure that represents Porous silicon complex particles 101 of the present invention, is (b) to represent Porous silicon complexThe figure of the near surface region S of particle 101 and inside particles region I.

Fig. 9 (a)～(c) is the figure that represents the summary of the first manufacture method of Porous silicon complex particles 101.

Figure 10 (a)～(c) is the figure that represents the summary of the second manufacture method of Porous silicon complex particles 101.

Figure 11 is the SEM photo of the inside of the Porous silicon particle of embodiment 1-12.

Figure 12 is the SEM photo of the Porous silicon particle of comparative example 1-1.

Figure 13 is the X-ray diffraction grating image of the Porous silicon particle of embodiment 1-12.

Figure 14 is the surperficial SEM photo of the Porous silicon complex particles of embodiment 2-1.

Figure 15 is the SEM photo in the cross section of the Porous silicon complex particles inside of embodiment 2-1.

Figure 16 is the surperficial SEM photo of the Porous silicon complex particles of embodiment 2-1.

Figure 17 is the X-ray diffraction grating image of the silicon particle of the Porous silicon complex particles of embodiment 2-1.

Figure 18 is the SEM photo of the Porous silicon particle of embodiment 3-7.

Figure 19 is the TEM photo of the silicon particle of the formation Porous silicon particle of embodiment 3-7.

Figure 20 is the size distribution of the silicon particle of the formation Porous silicon particle of embodiment 3-7.

Figure 21 is TEM photo, a SEAD picture (left side for the silicon particle of the formation Porous silicon particle of embodiment 3-8On).

Figure 22 be the operation (b) that represents embodiment 1-15 to the silicon particle after dipping in liquation metal and second-phaseSection S EM photo.

Figure 23 is that the operation (c) that represents embodiment 2-15 silicon rear, that remove the Porous silicon particle surface after second-phase is micro-The SEM photo of grain.

Figure 24 is the surperficial SEM photo of the Porous silicon particle of comparative example 2-4.

Figure 25 is the SEM photo of the Porous silicon particle of embodiment 3-1.

Figure 26 is the SEM photo of the Porous silicon particle of embodiment 3-2.

Figure 27 is the SEM photo of the Porous silicon particle of comparative example 3-3.

Figure 28 (a) is the photo of the microstructure of the intermediate alloy of embodiment 1-15, is (b) enlarged drawing of same photo.

Detailed description of the invention

[Porous silicon particle]

(formation of Porous silicon particle)

With reference to Fig. 1, Porous silicon particle 1 of the present invention is described. Porous silicon particle 1 is that multiple silicon particles 3 are connectClose and have the Porous silicon particle in continuous space, the shape of silicon particle 3 is preferably spherical, cylindric or polygonal column, siliconThe average x on particle diameter, strut diameter or the pillar limit of particulate 3 is 2nm～2 μ m, particle diameter, strut diameter or the pillar limit of silicon particle 3Standard deviation be 1～500nm, (σ/x) is 0.01～0.5 for the ratio of average x and standard deviation. Because on average x and standard are inclined to one sideThe ratio (so-called coefficient of alteration) of poor σ is in given scope, and therefore the size of silicon particle 3 is even.

The shape of silicon particle 3 has flat spherical, cylindric or polygonal column, the average longest diameter of silicon particle 3 orLongest edge a is 1.1～50 with the average ratio (a/b) of the shortest diameter or minor face b. Because silicon particle 3 has the flat shape of appropriatenessShape, therefore in the case of the negative electrode active material for lithium ion 2 primary cells by Porous silicon particle 1, in the time discharging and rechargingWhen silicon particle 3 carries out dilation, can fill space and expand, therefore have and in negative pole, be difficult to the effect that cracks. AndAnd, lower than 1.1 in the situation that, because isotropically producing dilation, and be easy to crack in negative pole. In addition, existExceed in 50 situation, for example, growing in fibrous situation, because of dilation in a direction set easily negativeExtremely, crack.

In addition, Porous silicon particle 1 possesses the three-dimensional mesh structure with continuous space, and engage and form by silicon particle 3,Average grain diameter is 0.1 μ m～1000 μ m, and average void fraction is 15～93%. In addition, Porous silicon particle 1 is characterised in that, isThe silicon, the remaining part that contain more than 80 atom % with the ratiometer of the element except oxygen contain intermediate alloy element described later, liquationElement, other the solid particle of inevitable impurity.

And, even form the oxide skin(coating) below 20nm on the surface of this silicon particle, also no problem in characteristic.

And then the surperficial oxide skin(coating) (oxide-film) of silicon particle can be by flooding after removing second-phase with hydrochloric acid etc.In the nitric acid of 0.0001～0.1N, form. Or, also can be by after utilizing decompression distillation to remove second-phase,Under the partial pressure of oxygen of 0.00000001～0.02MPa, keep forming.

In addition, as shown in Fig. 1 (b), Porous silicon particle 1 is divided into more than 50% near surface region on radial directionInside particles region I on S and radial direction below 50%, by micro-the silicon near surface region that forms Porous silicon particleThe average grain diameter of grain is made as Ds, the average grain diameter of the silicon particle in the inside particles region of formation Porous silicon particle is made as to DiTime, Ds/Di is 0.5～1.5.

In addition, the crystal grain (Figure 28) of intermediate alloy through in operation described later (b) to the dipping in liquation element andDealloying in operation (c) and in the process that changes, can obtain the many of the size suitable with the crystal grain of this intermediate alloyHole matter silicon particle (can not make it micronized particle because implementing to pulverize to wait). Porous silicon particle is divided on radial directionInside particles region I on more than 90% near surface region S and radial direction below 90%, will form Porous silicon grainThe average grain diameter of silicon particle in the near surface region of son is made as Es, will forms the silicon in inside particles region of Porous silicon particleWhen the average grain diameter of particulate is made as Ei, Es/Ei is 0.01～1.0. , in order not make the inside particles region of Porous silicon particleSilicon particle be less than the silicon particle near surface region, preferably do not make liquation element exceedingly flood to inside particles.

In addition, in Porous silicon particle, the voidage of the voidage Xs of near surface region S and inside particles region IThe ratio Xs/Xi of Xi is 0.5～1.5.

That is to say, Porous silicon particle of the present invention, near surface region and inside particles region, has identicalPore structure, particle entirety has roughly pore structure uniformly.

The silicon particle 3 that forms Porous silicon particle 1 is characterised in that, is that average grain diameter or average strut diameter are 2nm～2μ m, having crystalline monocrystalline, is the solid grain that contains silicon more than 80 atom % with the ratiometer of the element except oxygenSon. In addition, silicon particle 3 also can comprise the intermetallic compound that contains silicon alloy, silicon. And, if spherical particulate roughlyHave an independent existence, can measure particle diameter, but in the situation that belonging to approximate polygonal column, by the cross section vertical with major axisPost diameter or corresponding to average strut diameter on one side or average pillar limit for evaluating.

Three-dimensional mesh structure in the present invention means that picture is in produce in phase decomposition process common continuous structure or spongeThe interconnective structure of emptying aperture that structure is such. The emptying aperture diameter of the emptying aperture that Porous silicon particle has is 0.1～300nm left sideRight.

The average grain diameter of silicon particle 3, average strut diameter, average pillar limit are 2nm～2 μ m, are preferably 10～500nm,More preferably 15～100nm. In addition, the average void fraction of Porous silicon particle 1 is 15～93%, is preferably 30～80%, moreBe preferably 40～70%.

In addition, between silicon particle 3, engage partly the surface area that the area at the junction surface of silicon particle 3 is described silicon particleBelow 30%. That is to say, have an independent existence with supposition silicon particle 3 and compared with the surface area obtained, Porous silicon particle 1Surface area is more than 70%. And then the specific area of Porous silicon particle 1 is 1～100m²/g。

Porous silicon particle of the present invention exists owing to normally condensing, and therefore the average grain diameter of particulate here refers toThe average grain diameter of primary particle. The instrumentation of particle diameter will use the image information of electron microscope (SEM) and dynamic optical to fall apart simultaneouslyPenetrate the volume reference median diameter of photometer (DLS). Average grain diameter can utilize SEM image to confirm in advance shape of particle, with figurePicture analysis software (for example AsahiKaseiEngineering system " A is as くん " (registration mark)) is obtained particle diameter, or by particleBe scattered in solvent and utilize DLS (for example great mound electronics DLS-8000 processed) to measure. If particle fully in the time that DLS measuresDisperse, cohesion, does not utilize SEM and DLS can obtain roughly the same measurement result.

In addition, form the silicon particle of Porous silicon particle owing to being bonded with each other, therefore mainly use surface scan type electronicsMicroscope or infiltration type electron microscope are obtained average grain diameter.

In addition, so-called average strut diameter, is to be in the silicon particle of more than 5 bar-shaped (column), by its post in aspect ratioDiameter be defined as strut diameter. Using the mean value of this strut diameter as average strut diameter. This strut diameter is mainly passed throughThe SEM that carries out particle observes and obtains.

The average longest diameter of silicon particle, on average the shortest diameter is by using infiltration type electron microscope to carry out image processingAnd obtain.

First, silicon particle is pulverized with agate mortar, the material of gained is diluted with methanol solution, be added dropwise to carbonThe graticule mesh (φ 3mm) of tunicle goes up and is dried, and the material of gained is carried out to tem observation. But, material overlapping particle is got rid ofOutside evaluation object.

And confirming in this tem observation result and high-resolution SEM observed result is not having aspect the size of silicon particleChange.

In addition, the average grain diameter of flat spherical particle be the area of elliptoid particle is justified approximate, will be thusThe diameter of the particle diameter obtaining is obtained as diameter of equivalent circle, then calculates mean/standard deviation statistically.

More particularly, utilize tem observation to measure major diameter and the minor axis of silicon particle, using their mean value separately asAverage longest diameter, average the shortest diameter. In addition, calculate diameter of equivalent circle according to this each major diameter and minor axis, calculate that it is averageValue and standard deviation, as average grain diameter and the standard deviation of particulate.

Average void fraction refers to the ratio in the space in particle. Although the pore below sub-micron also can utilize nitrogen to inhaleAttached method is measured, but contains broad scope in pore size, can utilize electron microscope observation or mercury to pressEnter method (JISR1655 " the formed body pore footpath distribution determination method by mercury penetration method of fine ceramics ", according to skyThe relation derivation of the pressure while importing mercury in gap and mercury volume), (JISZ8830:2001 is by gas for gas adsorption methodThe specific area measuring method of powder (solid) of absorption) etc. mensuration.

Cooling speed when Porous silicon particle 1 of the present invention is manufactured according to the Si concentration of Si intermediate alloy or its intermediate alloySpend and the average grain diameter of formation 0.1 μ m～1000 μ m. And, by reducing Si concentration or accelerating cooling velocity, can make particle diameter becomeLittle. Aspect using with active material as negative pole, its average grain diameter is preferably 0.1～50 μ m, more preferably 1～30 μ m,More preferably 5～20 μ m. For this reason, in the situation that Porous silicon particle is little, use as agglomerate or granulation body. In addition,In the situation that Porous silicon particle is large, even if will use also without any problem after this Porous silicon particle coarse crushing.

In the junction surface (linking part) of silicon particle 3 and adjacent silicon particle 3, the thickness at described junction surface or diameter are phaseBelow 80% of diameter of a larger side's of adjacent silicon particle 3 silicon particle 3, junction surface is by crystallized silicon or Si oxide structureBecome. The thickness of junction surface or linking part is also by obtaining with tem observation silicon particle.

For this link thickness ratio, first, measure thickness or the diameter of the linking part of two silicon particles that engaged, withThe diameter of the silicon particle of the larger side in the middle of these two silicon particles compares. In the linking part of multiple silicon particles, be somebody's turn to doRelatively, its average out to is below 80%.

Multiple silicon particles 3 have produced orientation, the direction of the major axis of multiple silicon particles 3 all in certain direction ± 30 ° withIn.

(summary of the manufacture method of Porous silicon particle)

Use Fig. 2, the summary of the manufacture method to Porous silicon particle 1 describes.

First,, in operation (a), as shown in Fig. 2 (a), by the heating of silicon and intermediate alloy element, melting, produce in siliconBetween alloy 7.

In operation (b), silicon intermediate alloy 7 be impregnated in the liquation of liquation element, thereafter. Now, as Fig. 2 (b) instituteShow, because the intermediate alloy element of silicon intermediate alloy 7 is to stripping in liquation etc., and form the second-phase 9 that mainly comprises liquation element,Only silicon is separated out or is crystallized out as silicon particle 3. Second-phase 9 is alloys of intermediate alloy element and liquation element, or by with inBetween the alloying element liquation element of having replaced form. These silicon particles 3 are bonded with each other, and form three-dimensional mesh structure.

Thereafter, in operation (c), as shown in Fig. 2 (c), when utilization has been used the methods such as the dealloying of acid or alkali etc.,While removing second-phase, just can obtain the Porous silicon particle 1 that silicon particle 3 has been engaged.

Phenomenon in each operation is described. First, in operation (a), when silicon and intermediate alloy element (X) are meltedWhen melting, solidifying, will form the silicon intermediate alloy 7 as the alloy of silicon and intermediate alloy element.

Thereafter, in operation (b), in the time this silicon intermediate alloy being impregnated in liquation element (Y) bath specifying in table 1,Liquation element (Y) permeates in will spreading in silicon intermediate alloy, the intermediate alloy element (X) in silicon intermediate alloyForm alloy-layer with liquation element (Y) as second-phase. Or the intermediate alloy element (X) in alloy is to liquation element (Y)Stripping in metal bath, liquation element (Y) forms new second-phase. In this reaction, contained silicon atom quilt in silicon intermediate alloyLeft behind. Consequently, in the time that this silicon atom condenses with nano-scale from the state of diffusion, generate the network of silicon atom,Thereby form three-dimensional mesh structure. In addition, under the condition that forms large particle diameter, can obtain having produced the growth of facet clearlyParticle.

And then, utilize the three dimensional viewing solid of three-dimensional infiltration type electron microscope (JEM-2100 processed of for example NEC)Ground is distinguished and the engagement state of adjacent silicon particle, can determine ligancy according to the number of its joint. Also this can be joinedFigure place is got 2 and is enumerated as feature to 6.

In this operation (b) though in comprise silicon particle junction surface exist oxide also without any problem on surface.

And, in intermediate alloy and unalloyed silicon primary crystal in dipping process (b) to silicon particle to separate out generation very largeImpact, play a role as the product nucleus of silicon particle. Thus, can there is using this primary crystal as core manufacture the silicon of large particle diameterParticulate. In addition, manufacture silicon particle below 100nm aspect, there is not the composition of this silicon primary crystal or non-equilibrium in employing preferablySolidify.

According to above operation, for intermediate alloy element (X) and liquation element (Y), need following condition.

Condition 1: the fusing point of liquation element (Y) is than more than the low 50K of the fusing point of silicon.

Suppose that the fusing point of liquation element (Y) and the fusing point of silicon approach, at the liquation that silicon alloy is impregnated into liquation elementWhen middle, silicon will be dissolved in liquation, and therefore condition 1 is essential.

Condition 2: do not produce Si primary crystal in the time that silicon and intermediate alloy element are solidified.

In the time forming the alloy of silicon and intermediate alloy element (X), in the situation that increasing, silicon concentration works as in hypereutectic district, will form thick silicon primary crystal when in the territory. This silicon crystal do not produce the silicon atom in dipping process diffusion, condense again not shapeBecome three-dimensional mesh structure.

Condition 3: the solubility of silicon in liquation element is lower than 5 atom %.

This is because in the time that intermediate alloy element (X) and liquation element (Y) form second-phase, need to make in second-phase notContain silicon.

Condition 4: intermediate alloy element and liquation element are not separated into 2 phases.

In the situation that intermediate alloy element (X) and liquation element (Y) are separated into 2 phase, intermediate alloy element just can be fromIn silicon alloy, separate, thereby can not produce the diffusion of silicon atom/condense again. In addition, even if carry out by sour processing, also can beResidual intermediate alloy element in silicon particle.

If consider above condition 1～4, can be for the manufacture of intermediate alloy element and the liquation of Porous silicon particleThe combination of element is as follows. In addition, the ratio of silicon is more than 10 atom % of entirety, under intermediate alloy elementState below value the highest in the middle of the Si maximum level in table 1.

[table 1]

In the situation that using Co as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～77 atom %, and the average void fraction of the Porous silicon particle of gained is 15～84%.

In the situation that using Cr as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～82 atom %, and the average void fraction of the Porous silicon particle of gained is 12～85%.

In the situation that using Cu as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～30 atom %, and the average void fraction of the Porous silicon particle of gained is 47～85%.

In the situation that using Fe as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～67 atom %, and the average void fraction of the Porous silicon particle of gained is 15～85%.

In the situation that using Mg as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～50 atom %, and the average void fraction of the Porous silicon particle of gained is 42～92%.

In the situation that using Mn as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～67 atom %, and the average void fraction of the Porous silicon particle of gained is 15～85%.

In the situation that using Mo as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～98 atom %, and the average void fraction of the Porous silicon particle of gained is 15～88%.

In the situation that using Ni as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～55 atom %, and the average void fraction of the Porous silicon particle of gained is 15～85%.

In the situation that using P as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～50 atom %, and the average void fraction of the Porous silicon particle of gained is 48～93%.

In the situation that using Ti as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～82 atom %, and the average void fraction of the Porous silicon particle of gained is 15～89%.

In the situation that using Zr as intermediate alloy element, with respect to Si and intermediate alloy element sum, Si's containsAmount is 10～90 atom %, and the average void fraction of the Porous silicon particle of gained is 15～92%.

And, as intermediate alloy element, also can use the two or more elements of enumerating, and do in this caseFor the use of liquation element and any one corresponding liquation element of these intermediate alloy elements.

(manufacture method of Porous silicon particle)

Manufacture method to Porous silicon particle of the present invention describes.

First, by silicon with select in Free Surface 1 As, the Ba that record, 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, Yb, Zr structureThe intermediate alloy element of more than one of the group becoming so that the ratio of silicon be entirety 10～98 atom %, be preferably 15～50 formerThe mode of sub-% coordinates, and the mixture of gained is heated, melted in vacuum drying oven or non-oxidizing atmosphere stove etc. Thereafter, for exampleUse the thin plate continuous casting by twin-roll cast-rolling mill, or use single roll cast-rolling mill 11 as shown in Figure 3 etc., by melting siliconAlloy 13 drips from crucible 15, in the steel roller 17 of contact rotation, makes it to solidify, and manufactures the silicon of wire or thin ribbon shapedIntermediate alloy 19. And the foundry alloy of wire also can directly utilize spin processes manufacture. Or, also can be by silicon intermediate alloyMake and be different from foil-like wire or thin ribbon shaped, that there is certain length.

The thickness of the silicon intermediate alloy 19 of wire or thin ribbon shaped is preferably 0.1 μ m～2mm, more preferably 0.1～500 μ m,More preferably 0.1～50 μ m. Cooling velocity when the solidifying of silicon intermediate alloy is more than 0.1K/s, be preferably 100K/s withUpper, more preferably more than 400K/s. This is because the particle diameter of primary crystal generating by reducing early solidification, under contributing to shortenThe heat treatment time of one operation. In addition, diminish by the particle diameter that makes this primary crystal, the particle diameter of Porous silicon particle also can be pro rataDiminish. And, if the thickness of silicon alloy (intermediate alloy) greatly to more than 2mm, because Si content is high, therefore lacking toughness,Can produce break, broken string etc., therefore not ideal enough.

Then, silicon intermediate alloy is impregnated into corresponding with used intermediate alloy element be selected from the Ag that records in table 1,In the liquation of the liquation element in Al, Au, Be, Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, Zn, form silicon from phase decomposition, (silicon is micro-Separating out of grain) and as the second-phase of the alloy of intermediate alloy element and liquation element or by with intermediate alloy element substitutionThe second-phase that described liquation element forms. In this dipping process, start to form Si particulate. Dipping process for example uses the institute as Fig. 4The liquation device 21 showing, is impregnated into thin ribbon shaped silicon intermediate alloy 19 in the liquation 23 of liquation element. Thereafter, by submergence roller 25Or backing roll 27 is by its coiling. Liquation 23 is heated to than the temperature more than high 10K of the liquidus temperature of liquation element. At liquationAlthough the dipping in 23 also will be determined according to melt temperature, but be preferably 5 seconds above below 10000 seconds. This be because, ifImplement 10000 seconds above dippings, will generate thick Si grain. In addition, due to long dipping, only porous plastid particleSurperficial silicon particle can grow singularly. After this, that it is cooling under non-oxidizing atmosphere. And, as described later, preferably existIn liquation 23, do not contain aerobic.

Thereafter, using as the second-phase of the alloy of intermediate alloy element and liquation element or by with intermediate alloy element substitutionThe second-phase utilization that forms of the described liquation element operation of removing with at least a kind of dissolving of acid, alkali, organic solvent or by instituteStating second-phase heats up decompression and only this second-phase is evaporated to the operation of removing and removed. By removing second-phase, can obtainPorous silicon particle. And, as acid, the acid of non-dissolves silicon as long as dissolving intermediate alloy element and liquation element, can enumerate nitric acid, hydrochloric acid, sulfuric acid etc.

By with the dissolvings such as acid, alkali, organic solvent or the decompression distillation and after second-phase is removed of heating up, canThe Porous silicon particle that obtains being formed by particulate. In the situation that dissolving with acid, alkali, organic solvent etc., clean, be dried.The different grains that form 0.1 μ m～1000 μ m of cooling velocity while manufacture according to the silicon concentration of silicon intermediate alloy, silicon intermediate alloyFootpath. And, by reducing silicon concentration or accelerating cooling velocity, can make particle diameter diminish. What use with active material as negative poleAspect, its average grain diameter is preferably 0.1～50 μ m, more preferably 1～30 μ m, more preferably 5～20 μ m. Thus, manyIn the little situation of hole matter silicon particle, use the binding agent with electric conductivity to manufacture agglomerate or granulation body, be coated with after making pulp-likeCloth uses on collector body. In addition, in the situation that Porous silicon particle is large, even this Porous silicon particle is thick with mortar etc.Pulverize and use also without any problem. Owing to engaging partly between particulate, therefore can be broken easily.

(other examples of the manufacture method of Porous silicon particle)

As other examples of the manufacture method of Porous silicon complex particles 1, also can replace wire or thin ribbon shaped siliconIntermediate alloy 19, and use Powdered, granular, block silicon intermediate alloy.

First, by silicon and select in Free Surface 1 As, the Ba that record, 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, Yb, Zr structureThe intermediate alloy element of more than one of the group becoming so that the ratio of silicon be entirety 10～98 atom %, be preferably 15～50 formerThe mode of sub-% coordinates, and the mixture of gained is heated, melted in vacuum drying oven or non-oxidizing atmosphere stove etc. Utilize, thereafterManufacture the method for silicon intermediate alloy of grain/powdery or utilization with atomization as shown in Figure 5 with the ingot manufacture shown in Fig. 6The method that method obtains block ingot bar, carry out mechanical pulverizing is again manufactured granular silicon intermediate alloy.

Fig. 5 (a) represents to utilize the make powder gas atomization device 31 of shape silicon intermediate alloy 39 of gas atomization. ?In crucible 33, have and utilize silicon that eddy-current heating etc. melted and the silicon alloy 13 of intermediate alloy element, dripping from nozzle 35When this silicon alloy, blow the jet from the inert gas of gas spraying machine 37, the liquation of silicon alloy 13 is pulverized, make itForm Powdered silicon intermediate alloy 39 as droplet solidification.

Fig. 5 (b) represents to utilize the make powder rotating circular disk atomization of shape silicon intermediate alloy 51 of rotating circular disk atomizationDevice 41. In crucible 43, there are the silicon that melted and the silicon alloy 13 of intermediate alloy element, this silicon that drips from nozzle 45 closesGold falls the liquation of silicon alloy 13 on the rotating circular disk 49 of High Rotation Speed, tangentially applies shearing force and is brokenBroken, form Powdered silicon intermediate alloy 51.

Fig. 6 is that explanation utilizes ingot autofrettage to form the figure of the operation of bulk silicon intermediate alloy 57. First, by silicon alloy 13Liquation add mold 55 from crucible 53. Thereafter, interior by cooling silicon alloy 13 at mold 55, after solidifying, remove mold 55 and obtainTo bulk silicon intermediate alloy 57. As required bulk silicon intermediate alloy 57 is pulverized, obtained granular silicon intermediate alloy.

The thickness of granular silicon intermediate alloy is preferably 10 μ m～50mm, more preferably 0.1～10mm, more preferably 1～5mm. Cooling velocity when the solidifying of silicon alloy is more than 0.1K/s. And, if the thickness of silicon intermediate alloy arrives greatly 50mmAbove, heat treatment time is elongated, and therefore the particle diameter of Porous silicon particle is grown up, and coarsening occurs, so not ideal enough. These feelingsUnder condition, can pulverize by this silicon intermediate alloy being implemented to mechanical type, make 50mm and deal with below.

Then, silicon intermediate alloy is impregnated into corresponding with used intermediate alloy element be selected from the Ag that records in table 1,In the liquation of the liquation element in Al, Au, Be, Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, Zn, form silicon from phase decomposition and workFor the second-phase of the alloy of intermediate alloy element and liquation element. And the oxygen in this liquation is preferably reduced to 100ppm in advanceBelow, be preferably below 10ppm, more preferably below 2ppm. This be because, the dissolved oxygen in liquation and pasc reaction and form twoSilica, silicon taking be facet shape growth as core, there is coarsening. As its countermeasure, can utilize the solid such as charcoal, graphiteReducing material or non-oxidizing gas are reduced, and also can add in advance in addition the element strong with the affinity of oxygen. Soak at thisIn stain operation, start to form silicon particle.

Dipping process uses the liquation immersion system 61 as shown in Fig. 7 (a), granular silicon intermediate alloy 63 is put into dipping and useIn cage 65, be impregnated in the liquation 69 of liquation element. Now, as shown in Fig. 7 (a), move up and down by making to push cylinder 67, to siliconIntermediate alloy or liquation apply mechanical vibration, or utilize ultrasonic wave to apply vibration, or utilization has been used shown in Fig. 7 (b)Mechanical type mixer 81 mechanical agitation, used gas to blow plug 83 gas injection or electromagnetic force to stir moltenLiquid, just can advance reaction at short notice. Under non-oxidizing atmosphere mentioned and cooling, thereafter. By liquation 69 or 79Be heated to than the temperature more than high 10K of the liquidus temperature of liquation element. Although the dipping in liquation also will be according to liquation temperatureSpend and determine, but being preferably 5 seconds above below 10000 seconds. This be because, if implement 10000 seconds above dippings, Jiu HuishengBecome thick Si grain. In addition, due to long dipping, only the surperficial silicon particle of porous plastid particle is grown singularly.

, with aforesaid manufacture method in the same manner remove second-phase, obtain Porous silicon particle thereafter.

(effect of Porous silicon particle)

According to the present invention, can obtain the Porous silicon particle with three-dimensional mesh shape structure in the past not having.

According to the present invention, the entirety that can obtain particle has roughly the Porous silicon particle of pore structure uniformly. ThisBecause the separating out from silicon intermediate alloy of the silicon particle in liquation is to carry out in the liquation metal of high temperature, therefore liquation goldBelong to and be penetrated into inside particles.

If the negative electrode active material using Porous silicon particle of the present invention as lithium ion battery uses, can obtainHigh power capacity, long-life negative pole.

[Porous silicon complex particles]

(formation of Porous silicon complex particles)

With reference to Fig. 8, Porous silicon complex particles of the present invention is described. As shown in Fig. 8 (a), porous of the present inventionMatter silicon complex particles 101 is that silicon particle 103 engages and forms with silicon compound particle 105, Porous silicon complex particles 101Average grain diameter is 0.1 μ m～1000 μ m, and the average void fraction of Porous silicon complex particles 101 is 15～93%, has by connectingThe three-dimensional mesh structure that continuous space forms.

Three-dimensional mesh structure in the present invention refers to that picture is at the common continuous structure producing in phase decomposition process or sponge knotThe interconnective structure of emptying aperture that structure is such. The emptying aperture diameter of the emptying aperture that Porous silicon complex particles has is 0.1～300nm left and right.

In Porous silicon complex particles 101, the voidage Xs in the near surface region on radial direction more than 50%With the ratio Xs/Xi of the 50% voidage Xi taking interior inside particles region on radial direction as 0.5～1.5.

That is to say, Porous silicon complex particles of the present invention has phase near surface region and inside particles regionSame pore structure, particle entirety has roughly pore structure uniformly.

Voidage Xs can obtain by SEM observation is carried out in the surface of Porous silicon complex particles 101, voidageXi can carry out SEM observation by the position suitable with inside particles region in the cross section to Porous silicon complex particles 101And obtain.

In addition, the crystal grain of intermediate alloy in operation described later (b) to dipping and operation (c) in liquation elementIn dealloying and in the process that changes, the Porous silicon that can obtain the size suitable with the crystal grain of this intermediate alloy is multipleFit particle (can not wait micronized particle because of enforcement pulverizing). Porous silicon complex particles 101 is divided into radial directionInside particles region I on upper more than 90% near surface region S and radial direction below 90%, will form near surfaceThe average grain diameter of the silicon particle 103 of region S is made as Es, the average grain diameter of the silicon particle 103 of constituent particle interior zone I is made asWhen Ei, Es/Ei is preferably 0.01～1.0.

1 limit of the average grain diameter of silicon particle 103 or average pillar is 2nm～2 μ m, is preferably 10～500nm, more preferably20～300nm. In addition, average void fraction is 15～93%, is preferably 50～80%, more preferably 60～70%. In addition one,The crystal structure of individual silicon particle 103 is to have crystalline monocrystalline. In addition, silicon particle 103 is the ratios with the element except oxygenRate meter contain more than 80 atom % silicon, remaining part comprise intermediate alloy element described later, liquation element, other inevitablyThe solid particulate of impurity.

Silicon particle 103 be shaped as spherical or polygonal column, particle diameter, strut diameter or the pillar limit of silicon particle 103 flatAll x is 2nm～2 μ m, and the standard deviation on particle diameter, strut diameter or the pillar limit of silicon particle 103 is 1～500nm, average x and mark(σ/x) is 0.01～0.5 for the ratio of accurate deviations.

In addition, the shape of silicon particle 103 has flat spherical, cylindric or polygonal column, average longest diameter orThe ratio (a/b) of long limit a and average the shortest diameter or minor face b is 1.1～50.

In addition, as shown in Fig. 8 (b), Porous silicon complex particles 101 is divided into more than 50% surface on radial directionInside particles region I near zone S and radial direction below 50%, will form the surface of Porous silicon complex particlesThe average grain diameter of the silicon particle of near zone is made as Ds, by micro-the silicon in inside particles region that forms Porous silicon complex particlesWhen the average grain diameter of grain is made as Di, Ds/Di is 0.5～1.5.

Average grain diameter Ds can obtain by SEM observation is carried out in the surface of Porous silicon complex particles 1, average particleFootpath Di can carry out SEM observation by the cross section at the position suitable with inside particles region to Porous silicon complex particles 1And obtain.

The average grain diameter of silicon compound particle 105 is 50nm～50 μ m, is preferably 100nm～20 μ m, more preferably 200nm～10 μ m. In addition, on composition, be by select free As, Ba, Ca, Ce, Co, Cr, Cu, Er, Fe, Gd, Hf, Lu, Mg, Mn, Mo,The group that Nb, Nd, Ni, Os, Pr, Pt, Pu, Re, Rh, Ru, Sc, Sm, Sr, Ta, Te, Th, Ti, Tm, U, V, W, Y, Yb, Zr formThe silicon of more than one complex element, 50～75 atom % and intermediate alloy element described later, liquation element, other can notThe impurity avoided forms solid has a crystalline particle. In addition, as a rule, silicon compound particle 105 compares silicon particle103 is large.

In addition, even on the surface of Porous silicon complex particles 101, i.e. silicon particle 103 or silicon compound particle 105Upper, formation thickness is below 20nm or counts below 10% with the size ratio of each silicon particle 103 or silicon compound particle 105Oxide skin(coating), also no problem in characteristic.

The surperficial oxide skin(coating) of Porous silicon complex particles 101 can be by being impregnated into removing after second-phaseIn the nitric acid of 0.0001～0.1N, form. Or, also can be by removing after second-phase, 0.00000001～Under the partial pressure of oxygen of 0.02MPa, keep forming. In the time forming the oxide skin(coating) of this silicon etc., Porous silicon complex particles 101 existsAlso can be very stable in atmosphere, need in glove box etc., not dispose.

Porous silicon complex particles of the present invention exists owing to as a rule condensing, and therefore the average grain diameter of particle existsHere refer to the average grain diameter of primary particle. The instrumentation of particle diameter will use the image information of electron microscope (SEM) simultaneously and moveThe volume reference median diameter of state light scattering photometer (DLS). Average grain diameter can utilize SEM image to confirm in advance particle shapeShape, for example, obtains particle diameter by image analysis software (AsahiKaseiEngineering system " A is as くん " (registration mark)), orParticle is scattered in solvent and utilizes DLS (for example great mound electronics DLS-8000 processed) to measure. If particle in the time that DLS measuresDisperse fully, cohesion, does not utilize SEM and DLS can obtain roughly the same measurement result.

In addition, the silicon particle of formation Porous silicon complex particles and silicon compound particle are owing to being bonded with each other, therefore mainUse surface scan type electron microscope or infiltration type electron microscope to obtain average grain diameter.

Average void fraction refers to the ratio in the space in particle. Pore below sub-micron also can utilize nitrogen adsorption methodMeasure, but contain broad scope in pore size, can utilize electron microscope observation or mercury penetration method(JISR1655 " the formed body pore footpath distribution determination method by mercury penetration method of fine ceramics ", according in spaceImport the relation derivation of pressure when mercury and mercury volume) etc. mensuration. In addition, BET specific area can be utilized nitrogen adsorptionMethod is measured.

When Porous silicon complex particles 101 of the present invention is manufactured according to the Si concentration of Si intermediate alloy or this intermediate alloyCooling velocity different and form the particle diameter of 0.1 μ m～1000 μ m. And, by reducing Si concentration or accelerating cooling velocity, meetingParticle diameter is diminished. Aspect using with active material as negative pole, its average grain diameter is preferably 0.1～50 μ m, and more preferably 1～30 μ m, more preferably 5～20 μ m. Thus, in the situation that Porous silicon complex particles is little as agglomerate or makePlastochondria uses. In addition, in the situation that Porous silicon complex particles is large, even by this Porous silicon complex particles coarse crushingRear use is also without any problem.

In the junction surface of silicon particle 103 and adjacent silicon particle 103, the thickness at junction surface or diameter are that adjacent silicon is micro-Below 80% of diameter of a larger side's of grain 103 silicon particle 103, junction surface is made up of crystallized silicon or Si oxide.

Multiple silicon particles 103 have produced orientation, the direction of the major axis of multiple silicon particles 103 all in certain direction ±In 30 °.

Measure for example SEM image based on as shown in Figure 22,23 and carry out, utilize average with respect to the angle of the direction of growthThe size of the skew of value is carried out regulation orientation angles.

(summary of the first manufacture method of Porous silicon complex particles)

Use Fig. 9, the summary of the manufacture method to Porous silicon complex particles 101 describes.

First,, as shown in Fig. 9 (a), by silicon, intermediate alloy element and the heating of complex element, melting, in the middle of making silicon, closeGold 107. Now, when by silicon, complex element and the melting of intermediate alloy element, while solidifying, will form silicon and complex elementThe silicon compound particle forming with the intermediate alloy 107 of intermediate alloy element and by silicon and complex element.

,, silicon intermediate alloy 107 is impregnated in the liquation of liquation element thereafter. When silicon intermediate alloy 107 is impregnated into moltenWhile melting in metal bath, liquation element will be to infiltration in silicon intermediate alloy 107. Now, at intermediate alloy element and liquation elementWhen forming alloy solid phase, liquation element is also further soaking into, thereby forms liquid phase. In this liquid phase region, remain siliconAtom and complex element. This silicon atom, complex element are in the time starting to condense from the state of diffusion, and silicon particle 103 is separated out, and doesBecome the network of the alloy of silicon atom and complex element, form three-dimensional mesh structure. That is to say, as shown in Fig. 9 (b), because of siliconThe intermediate alloy element of intermediate alloy 107 is to stripping in liquation etc., and forms second-phase 109, and silicon is separated out as silicon particle 103.Second-phase 109 is alloys of intermediate alloy element and liquation element, or by with intermediate alloy element substitution liquation element structureBecome. In addition, silicon compound particle 105 is not affected by the liquation of liquation element and former state is residual unchangeably. These silicon particles 103,Silication is closed a particle 105 and is bonded with each other, and forms three-dimensional mesh structure.

And, in the dipping process in bath of molten metal, even independent silicon primary crystal or silicon and the complex element of siliconCompound infiltration have liquation element, can not cause condensing again of silicon atom or complex element, silicon primary crystal, complex element yetCompound former state residual unchangeably. Thus, preferably the cooling velocity when improving the making of silicon intermediate alloy 107, entersTheir particle diameter control of row.

,, as shown in Fig. 9 (c), when having been used the methods such as the dealloying of acid or alkali etc., utilization removes second-phase 109 thereafterTime, the Porous silicon complex particles 1 that just can obtain the silicon particle 103 to engage with silicon compound particle 105.

According to above operation, for intermediate alloy element, complex element and liquation element, need following condition.

Condition 1: the fusing point of liquation element is than more than the low 50K of the fusing point of silicon.

Suppose that the fusing point of liquation element and the fusing point of silicon approach, at the liquation that silicon intermediate alloy is impregnated into liquation elementWhen middle, silicon will be dissolved in liquation, and therefore condition 1 is essential.

In the time forming the alloy of silicon and intermediate alloy element, in the situation that increasing, silicon concentration works as in hypereutectic regionTime, will form thick silicon primary crystal. This silicon primary crystal do not produce the silicon atom in dipping process diffusion, condense again, do not formThree-dimensional mesh structure.

This is because in the time of intermediate alloy element and liquation element formation second-phase, need to make not contain in second-phase silicon.

In the situation that intermediate alloy element and liquation element are separated into 2 phase, intermediate alloy element just can not be from silicon alloyMiddle separation, thus can not produce silicon atom diffusion, condense again. And then, even if carry out by sour processing, also can be at silicon particleIn residual intermediate alloy element.

Condition 5: silicon is not separated into 2 phases with complex element.

In the situation that silicon is easily separated into 2 phase with complex element, finally cannot obtain by silicon and complex elementThe silicon compound particle that alloy forms.

Condition 6: the intermediate alloy element corresponding with liquation element do not comprise compound volume elements in the element that can selectElement.

Complex element is to can be used as the element that intermediate alloy element is selected, and is possessing foregoing intermediate alloy unitIn the situation of feature of element, liquation element and complex element formation second-phase, compound volume elements in the time carrying out by sour processingElement is just removed.

If consider above condition 1～6, can be for the manufacture of the intermediate alloy element of Porous silicon complex, multipleThe voidage of fit element and the combination of liquation element and the Porous silicon complex of gained is as follows. In addition, complexThe ratio of element is 1～33 atom % of silicon. And then the ratio of silicon is with respect to silicon, intermediate alloy element and described complexElement sum is more than 10 atom %, and is the value of the Si maximum level in the following table 2 corresponding with intermediate alloy element(in the situation that comprising multiple intermediate alloy element, be by the Si maximum level in the table 2 corresponding with each intermediate alloy elementCorresponding to the ratio of intermediate alloy element the value of distributing) below. In addition, in the situation that containing multiple intermediate alloy element,Use can jointly be used in complex element and the liquation element in each intermediate alloy element.

[table 2]

In the operation of formation silicon intermediate alloy 107, preferred fabrication silicon (X atom %), intermediate alloy element (Y atom %)With a kind of above complex element (Z₁、Z₂、Z₃, atom %) have in the middle of the silicon of the composition that meets following formulaAlloy. And [Si maximum level] is the value of the Si maximum level in the described table 2 corresponding with intermediate alloy element, have manyIn the situation of individual intermediate alloy element, be that the Si maximum level of each intermediate alloy element is divided with the ratio of each intermediate alloy elementThe value of joining. In addition, in the situation that having multiple intermediate alloy element, Y atom % is the ratio sum of multiple intermediate alloy elements.

10≤X < [Si maximum level] (1)

10≤a ÷ (a+Y) × 100≤[Si maximum level] (2)

Wherein, a=X-1.5 × (Z₁+Z₂+Z₃、····)

(the first manufacture method of Porous silicon complex particles)

Manufacture method to Porous silicon complex particles of the present invention describes. And, below use Porous siliconThe device using in the manufacture method of particle describes, and gives identical symbol to each intermediate alloy, and for the manufacture of porousThe intermediate alloy of matter silicon complex particles contains complex element, in this with centre for the manufacture of Porous silicon particleAlloy difference.

First the group that, uses silicon, selects Co, the Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Ti, the Zr that record in Free Surface 2 to form1 kind of above intermediate alloy element and the table 2 corresponding with intermediate alloy element in more than one the compound volume elements recordedElement, coordinates silicon, intermediate alloy element, complex element, by the heating in vacuum drying oven etc. of the mixture of gained, melt. Now,Form silicon and the alloy of intermediate alloy element and the compound of silicon and complex element.

, for example, use single roll cast-rolling mill 11 as shown in Figure 3 etc. thereafter, by melting silicon alloy 13 from crucible 15Drip, in contacting with the steel roller 17 of rotation, make it to solidify, manufacture in the middle of thin ribbon shaped silicon intermediate alloy 19 or wire siliconAlloy. Cooling velocity when the solidifying of silicon intermediate alloy is more than 10K/s, more than being preferably 100K/s, and more preferably 200K/sAbove. The high speed of this cooling velocity contributes to reduce the silicon compound particle in early solidification generation in microstructure. SubtractThe size of little silicon compound particle contributes to shorten the heat treatment time in subsequent processing. Thin ribbon shaped silicon intermediate alloy 19 or wireThe thickness of silicon intermediate alloy be 0.1 μ m～2mm, be preferably 0.1～500 μ m, more preferably 0.1～50 μ m. Or, also canSilicon intermediate alloy is made to the foil-like that is different from the certain length of having of wire or thin ribbon shaped. In addition, intermediate alloy is micro-The preferably 0.1 μ m～1mm of average-size that sees tissue, is preferably 0.1～500 μ m, more preferably 0.1～300 μ m. This be because ofFor, in operation (b), to flood in bath of molten metal in the situation that, bathe element and preferentially spread crystal boundary, thereafter in crystal boundaryDiffusion.

Then, silicon intermediate alloy is impregnated into be selected from table 2 Ag, the Al corresponding with intermediate alloy element that record, Au,In the metal bath of at least a kind of above liquation element of Be, Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, Zn, Si is carried out from dividing mutuallySeparate, form as the second-phase of the alloy of intermediate alloy element and liquation element or by with intermediate alloy element substitution described inThe second-phase that liquation element forms. Dipping process for example uses liquation immersion system 21 as shown in Figure 4, in the middle of thin ribbon shaped siliconAlloy 19 or wire silicon intermediate alloy are impregnated in the liquation 23 of liquation element. Thereafter, will by submergence roller 25 or backing roll 27Its coiling. Liquation 23 is heated to than the temperature more than high 10K of the liquidus temperature of liquation element. Though the dipping in liquation 23So also to determine according to melt temperature, but be preferably 5 seconds above below 10000 seconds. This be because, if implement 10000 secondsAbove dipping, will generate thick Si grain. In addition, due to long dipping, only the surperficial silicon of porous plastid particle is micro-Grain is growth singularly. By dipping after thin ribbon shaped silicon intermediate alloy 19 cooling under non-oxidizing atmosphere, obtain silicon particle 103,The complex of silicon compound particle 105, second-phase 109.

Thereafter, using as the second-phase 109 of the alloy of intermediate alloy element and liquation element or by with or intermediate alloy unitThe more than at least a kind dissolving of second-phase 109 use acid that the described liquation element that element has been replaced forms, alkali, organic solvent and general onlyThis second-phase 109 is removed, and cleans, is dried. As acid, as long as dissolving intermediate alloy element and liquation element, non-dissolves siliconAcid, can enumerate nitric acid, hydrochloric acid, sulfuric acid etc. Or by this second-phase 109 is heated up decompression and only by this second-phaseEvaporation is removed.

And, removing after second-phase 109, obtain the thick agglomerate of Porous silicon complex particles 101, therefore useThe pulverizing such as ball mill, the average grain diameter that makes agglomerate is 0.1 μ m～20 μ m.

(other examples of the first manufacture method of Porous silicon complex particles 101)

As other examples of the first manufacture method of Porous silicon complex particles 101, also can replace wire or thinBanded silicon intermediate alloy 19 and use Powdered, granular, block silicon intermediate alloy.

First the group that, uses silicon, selects Co, the Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Ti, the Zr that record in Free Surface 2 to form1 kind of above intermediate alloy element and the table 2 corresponding with intermediate alloy element in a kind of above complex element recording,Silicon, intermediate alloy element, complex element are coordinated, by the heating in vacuum drying oven etc. of the mixture of gained, melt.

,, utilize the silicon intermediate alloy of the grain/powdery approximate spherical with the atomization manufacture as shown in Fig. 5 (a), (b) thereafterMethod or utilize with the ingot autofrettage shown in Fig. 6 and obtain block ingot bar, carry out as required mechanical pulverizing againMethod make powder shape, granular or block silicon intermediate alloy.

Fig. 5 (a) represents to utilize the make powder gas atomization device 31 of shape silicon intermediate alloy 39 of gas atomization. ?In crucible 33, have and utilize silicon that eddy-current heating etc. melted and the silicon alloy 13 of intermediate alloy element and complex element, willWhen this silicon alloy 13 drips from nozzle 35, blow from the gas that has been supplied to the ejection such as inert gas, air gas 36The gas jet 38 of body spraying machine 37, pulverizes the liquation of silicon alloy 13, makes it to form in Powdered silicon as droplet solidificationBetween alloy 39.

Fig. 5 (b) represents to utilize the make powder rotating circular disk atomization of shape silicon intermediate alloy 51 of rotating circular disk atomizationDevice 41. In crucible 43, there are the silicon that melted and the silicon alloy 13 of intermediate alloy element and complex element, by this silicon alloyFrom nozzle 45, drip, the liquation of silicon alloy 13 is fallen on the rotating circular disk 49 of High Rotation Speed, tangentially apply and cutShear force and by its fragmentation, form Powdered silicon intermediate alloy 51.

Fig. 6 is that explanation utilizes ingot autofrettage to form the figure of the operation of bulk silicon intermediate alloy 57. First, by silicon alloy 13Liquation add mold 55 from crucible 53. Thereafter, interior by cooling silicon alloy 13 at mold 55, after solidifying, remove mold 55 and obtainTo bulk silicon intermediate alloy 57. Bulk silicon intermediate alloy 57 former states can be used unchangeably, or also can enter as requiredRow is pulverized, and uses as granular silicon intermediate alloy.

The particle diameter of Powdered, granular or block silicon intermediate alloy is preferably 10 μ m～50mm, more preferably 0.1～10mm, more preferably 1～5mm. Cooling velocity when the solidifying of silicon alloy is more than 0.1K/s. And, if in the middle of siliconThe thickness of alloy is greatly to more than 50mm, and heat treatment time is elongated, and therefore the particle diameter of Porous silicon complex particles is grown up, therebyThere is coarsening, so not preferred. In this situation, can pulverize, thickness is established by this silicon intermediate alloy is implemented to mechanical typeFor 50mm deals with below.

The crystal grain diameter of the intermediate alloy being made up of this silicon and described intermediate alloy element or described complex element is bestBe below 1000 μ m, more preferably below 500 μ m, more preferably below 50 μ m. If crystal grain diameter is more than 1000 μ m,The diffusion of the crystal boundary of the liquation element in operation (b) will preferentially be carried out, and intragranular diffusion is stagnated, thereby cannot carry out uniformlyReaction.

Then, silicon intermediate alloy is impregnated into the liquation unit recording in the table 2 corresponding with used intermediate alloy elementIn the liquation of element, form silicon from phase decomposition with as the second-phase of the alloy of intermediate alloy element and liquation element. And,Well the oxygen in this liquation is reduced to below 100ppm in advance, is preferably below 10ppm, more preferably below 2ppm. This be because ofFor, the dissolved oxygen in liquation and pasc reaction and form silica, silicon taking be the growth of facet shape as core, there is coarsening.As its countermeasure, can utilize the solid reduction such as charcoal, graphite material or non-oxidizing gas to be reduced, in addition also can be pre-First add the element strong with the affinity of oxygen. In this dipping process, start to form silicon particle.

Dipping process uses the liquation immersion system 61 as shown in Fig. 7 (a), granular silicon intermediate alloy 63 is put into dipping and useIn cage 65, be impregnated in the liquation 69 of liquation element. Now, as shown in Fig. 7 (a), move up and down by making to push cylinder 67, to siliconIntermediate alloy or liquation apply mechanical vibration, or utilize ultrasonic wave to apply vibration, or utilization has been used shown in Fig. 7 (b)Mechanical type mixer 81 mechanical agitation, used gas to blow plug 83 gas injection or electromagnetic force to stir moltenLiquid, just can advance reaction at short notice. Under non-oxidizing atmosphere mentioned and cooling, thereafter. By liquation 69 or 79Be heated to than the temperature more than high 10K of the liquidus temperature of liquation element. Although the dipping in liquation also will be according to liquation temperatureSpend and determine, but being preferably 5 seconds above below 10000 seconds. This be because, if implement 10000 seconds above dippings, Jiu HuishengBecome thick Si grain. In addition, due to long dipping, only the surperficial silicon particle of porous plastid particle is grown singularly. And,Aforesaid Powdered, granular, block and so on the shape of silicon intermediate alloy just by shape little aspect ratio (aspect ratio be 5 withUnder) silicon intermediate alloy be called powder, grain, piece according to size, be not strict definition. In addition, in the middle of granular siliconAlloy 63,73,93 is to close in the middle of aforesaid Powdered, granular, bulk silicon intermediate alloy is expressed as to granular silicon typicallyGold.

, with aforesaid manufacture method in the same manner remove second-phase, obtain Porous silicon complex particles thereafter.

(the second manufacture method of Porous silicon complex particles)

The second manufacture method to Porous silicon complex particles of the present invention describes. In the second manufacture method, asShown in Figure 10 (a), form the silicon intermediate alloy 111 being formed by silicon and intermediate alloy element. Thereafter, by being impregnated in liquation unitIn element, add in the liquation of complex element, and as shown in Figure 10 (b), formed silicon particle 103, silicon compound particle 105 andSecond-phase 109. ,, as shown in Figure 10 (c), remove second-phase 109 and obtain Porous silicon complex particles 101 thereafter.

Below, the second manufacture method is specifically described.

First, the powder of silicon is formed with Co, the Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Ti, the Zr that select record in Free Surface 2The powder of a kind of group above intermediate alloy element so that silicon (X atom %), intermediate alloy element (Y atom %) meet formula(3) mode is dissolved.

X ÷ (X+Y) × 100≤[Si maximum level] (3)

Thereafter, identical with the first manufacture method, use single roll cast-rolling mill 11 as shown in Figure 3 etc., manufacture as silicon with inBetween thin ribbon shaped silicon intermediate alloy 19 or the wire silicon intermediate alloy of alloy of alloying element. Or, utilize as Fig. 5 (a), (b) instituteThe atomization the showing shape silicon intermediate alloy that makes powder. In addition, the also ingot of cast silicon intermediate alloy as shown in Figure 6, by itMechanical crushing and make granular.

Then, silicon intermediate alloy is impregnated in table 2 Ag, the Al corresponding with intermediate alloy element that record, Au, Be,In at least a kind of above liquation element of Bi, Cd, Ga, In, Pb, Sb, Sn, Tl, Zn respectively following with 10 atom %, add up toThe complex element of more than one corresponding with intermediate alloy element of recording in the following interpolation of 20 atom % table 2 and closing of makingGold bathe in, form Si the compound from phase decomposition and Si and complex element formation, as intermediate alloy element and liquationThe second-phase of the alloy of element and/or by with intermediate alloy element substitution the second-phase that forms of described liquation element. DippingOperation is used liquation immersion system 21 as shown in Figure 4, and thin ribbon shaped silicon intermediate alloy 19 or wire silicon intermediate alloy are impregnated intoIn the liquation 23 of liquation element, or use liquation immersion system or liquation treating apparatus as shown in Figure 7, close in the middle of granular siliconGold is impregnated in the liquation of liquation element. Liquation 23 is heated to than the temperature more than high 10K of the liquidus temperature of liquation element.Although the dipping in liquation 23 also will be determined according to melt temperature, but be preferably 5 seconds above below 10000 seconds. This be because ofFor, if implement 10000 seconds above dippings, will generate thick Si grain. In addition, due to long dipping, only PorousThe surperficial silicon particle of body particle can be grown singularly. It is cooling under non-oxidizing atmosphere, obtain silicon particle 103, silicationThe complex of compound particle 105, second-phase 109.

And, the liquation that also can record in this silicon intermediate alloy is impregnated into the table 2 corresponding with intermediate alloy elementAfter in the bath of element, be impregnated in the table 2 corresponding with intermediate alloy element in the liquation element of recording with each 10 atom % withUnder, add up to that 20 atom % are following adds corresponding with the intermediate alloy element complex element formation recorded in Free Surface 2 selectedThe complex element of more than one of group and in the alloy baths of making.

And, in operation (b) the intrinsic preferred growth orientation of the metal of bath of molten metal as shown in table 3 become domination wantCause, can control the orientation of silicon particle. And then, operation (c) though in remove second-phase and also can maintain silicon particle orientation. ByThis, can be by selecting bath of molten metal to control the orientation of silicon particle.

And, although reason is not clear, but as the growth orientation more preferably<1010 of liquation element>.

[table 3]

Element	Growth orientation
		Ag	<100>
Al	<100>
		Au	<100>
Be	<1010>
		Bi	<1010>
Cd	<100>
		Ga	<1010>
In	<100>
		Pb	<100>
Sb	<100>
		Sn	<100>
Tl	<1010>
		Zn	<1010>

Figure 22 be in the operation (b) that represents embodiment 1-15 described later to the silicon particle after dipping in liquation metal and theThe section S EM photo of two-phase. Look that the region of blackout is the second-phase that comprises bismuth, look that the position of turning white is silicon particle.Known silicon particle is arranged along the interior upper right of figure. This be because, forming when second-phase, along as the easily knot of growth of bismuthBrilliant orientation<1010>formation silicon particles.

Figure 23 removes the Porous silicon particle surface after second-phase after the operation (c) that is illustrated in embodiment 2-15 described laterThe SEM photo of silicon particle. Known flat columned silicon particle is arranged along the interior upper left of figure.

, with aforesaid first manufacture method in the same manner only second-phase 109 removed, obtain Porous silicon complex grain thereafterSon 101.

(effect of Porous silicon complex particles)

According to the present invention, can obtain the Porous silicon complex particles with three-dimensional mesh shape structure in the past not having.

According to the present invention, the entirety that can obtain particle has roughly the Porous silicon complex grain of pore structure uniformlySon. This is because the separating out from silicon intermediate alloy of the silicon particle in liquation is to carry out in the liquation metal of high temperature, therefore moltenLiquid metal penetration is to inside particles.

If the negative electrode active material using Porous silicon complex particles of the present invention as lithium ion battery uses, just canTo obtain high power capacity, long-life negative pole. Particularly, because complex element is the element that is difficult to inhale storage lithium compared with silicon, because ofWhen this storage of suction at lithium ion, complex element is difficult to expand, and the expansion of silicon is inhibited, and can obtain more long-life negative pole.In addition, due to high with silicon compound particle electric conductivity compared with silicon of the compound of complex element as silicon, therefore the present inventionPorous silicon complex particles can tackle discharging and recharging rapidly compared with common silicon particle.

[embodiment]

Below, use embodiment and comparative example to be specifically described the present invention. Embodiment 1-1～1-16 is relevantThe embodiment of silicon Porous particle, embodiment 2-1～2-16 is the Porous silicon complex grain about comprising complex elementThe embodiment of son.

[embodiment 1]

(embodiment 1-1)

With the ratio of Si:Co=55:45 (atom %), silicon (block, purity: more than 95.0%) is coordinated with cobalt, by itsFusing at 1480 DEG C in vacuum drying oven. ,, use single roll cast-rolling mill to produce thickness of slab with the cooling velocity chilling of 800K/s thereafterThe silicon alloy strip processed of 200 μ m. It is flooded in the tin melt of 940 DEG C after 1 minute to chilling in argon gas immediately. Utilizing shouldProcess, obtain 2 phase complexs of Si and the second-phase being formed by Co-Sn or Sn. By water-soluble at nitric acid 20% this 2 phase complexIn liquid, flood 5 minutes, obtain Porous silicon particle.

(embodiment 1-2～1-11)

Creating conditions of each embodiment, comparative example is summarised in table 4. Embodiment 1-2～1-11 utilizes shown in table 4Intermediate alloy element, the cooperation ratio of each element etc. create conditions, the method for other and embodiment 1-1 obtains many in the same mannerHole matter silicon complex.

(embodiment 1-12)

With the ratio of Si:Mg=12:88 (atom %), silicon (block, purity: more than 95.0%) is coordinated with magnesium, by itsFusing at 1090 DEG C in vacuum drying oven. Thereafter, cooling in mold, produce the square big or small silicon alloy ingot processed of 5mm. WillIt floods after 1 minute in the plumbous liquation of 470 DEG C, immediately chilling in argon gas. Utilize this processing obtain Si with by Mg-Pb or2 phase complexs of the second-phase that Pb forms. This 2 phase complex is flooded 5 minutes in nitric acid 20% aqueous solution, obtain PorousSilicon particle.

(embodiment 1-13～1-16)

Embodiment 1-13～1-16 manufactures bar at the cooperation ratio of the intermediate alloy element shown in table 4, each element etc.Under part, the method for other and embodiment 1-12 obtains Porous silicon complex in the same manner.

(comparative example 1-1)

Ratio with Si:Mg=55:45 (atom %) coordinates Si powder with magnesium dust, by its in argon gas atmosphereFusing at 1087 DEG C. ,, use twin-roll cast-rolling mill to produce the silicon alloy band processed of thickness of slab 1mm with the cooling velocity of 200K/s thereafter.It is flooded after 1 minute in the bismuth liquation of 890 DEG C, immediately chilling in argon gas. By this complex at nitric acid 20% aqueous solutionMiddle dipping 5 minutes.

(comparative example 1-2)

The silicon particle of average grain diameter 5 μ m (SIE23PB, high-purity chemical institute system) is used to the hydrogen that has mixed 20wt%The nitration mixture of the nitric acid of fluoric acid water and 25wt% carries out etch processes, filters and obtains Porous silicon particle.

(comparative example 1-3)

Use the silicon particle (SIE23PB, high-purity chemical institute system) of average grain diameter 5 μ m.

[evaluation]

Evaluation result is summarised in table 5. And embodiment 1-13, has therefore used because silicon particle is large to 1-16The particle diminishing after pulverizing with mortar carries out evaluating characteristics. For example, the particle footpath of the Porous silicon particle of embodiment 1-13Mean the Porous that the Porous silicon particle pulverizing of original average grain diameter 130 μ m is obtained to average grain diameter 33 μ mSilicon particle.

[table 4]

[table 5]

As shown in table 5, the average grain diameter x of the silicon particle of each embodiment is in 2nm～2 μ m, the mark of the particle diameter of silicon particleAccurate deviations is 1～500nm, and (σ/x) is 0.01～0.5 for the ratio of average x and standard deviation. In addition, in each embodiment, on averageLong diameter a is 1.1～50 with the average ratio (a/b) of the shortest diameter b. In addition the linking part of silicon particle and adjacent silicon particle,Thickness is below 80% with the ratio (link thickness ratio) of the diameter of a larger side's of adjacent silicon particle silicon particle.

In each embodiment, owing to being that manufacture method by having utilized dealloying (dealloying) is made satisfiedThe Porous silicon particle of each important document of recording in technical scheme 1, therefore after the circulation of 50 times in each embodiment, capacity dimension holdup is high,Cycle characteristics is good. Can infer, because the particle diameter of silicon particle is even, the therefore expansion/receipts of the active material in the time discharging and rechargingWhen contracting, do not have stress to the inhomogeneous position of particle diameter concentrate, thereby cycle characteristics is increased substantially.

Each embodiment is compared with comparative example 1-1～1-3, and after 50 circulations, capacity dimension holdup is high, by discharging and recharging repeatedlyThe ratio of the reduction of the discharge capacity causing is little, therefore can estimate as the life-span of battery long.

In addition, in each embodiment, because negative electrode active material is the porous with three-dimensional mesh structure or continuous spaceTherefore matter silicon particle, even if produce the volume of the alloying by Li and the Si/expansion/contraction that de-alloying causes while discharging and rechargingChange, also can not produce breaking or micronizing of silicon particle, discharge capacity sustainment rate is high.

If compared in further detail, in comparative example 1-1, in the time that intermediate alloy is made as primary crystal crystallizationGo out pure Si, and then generate eutectic structure (Si and Mg latter stage solidifying₂Si). This primary crystal Si is the thick grain that reaches 10 μ m left and rightSon. Even if be impregnated in bismuth liquation, can not make it miniaturization yet, on the contrary can coarsening, also can be with after etching work procedureForm is originally remaining. Can think thus, repeatedly carrying out the intrusion of Li/while emitting, with the Si simple substance headed by thick Si withoutMethod is followed the Volume Changes by the expansion/contraction due to the alloying of discharge and recharge=Li and Si/de-alloying, breaks or collapsesCollapse, the ratio of losing current collection passage or electrode function becomes many, the lifetime of battery.

In comparative example 1-2, because the etching that utilizes hydrofluoric acid or nitric acid forms pore structure, therefore at particle central partBe formed with the position that does not form pore. Can think, the part of this core cannot be followed by the Volume Changes due to discharging and recharging, circulationCharacteristic is poor.

In comparative example 1-3, owing to being the simple silicon particle without pore structure, therefore can think, cannot followBy the Volume Changes due to discharging and recharging, cycle characteristics is poor.

(evaluation of shape of particle)

Use scanning infiltration type electron microscope (NEC's system, JEM3100FEF) has carried out Porous silicon particleThe observation of shape of particle. In Figure 11, express the SEM photo of the particle of embodiment 1-12, Tu12Zhong, expresses comparative example 1-The SEM photo of 1 particle. In Figure 11, observe, the silicon particle of particle diameter 20nm～100nm be bonded with each other and assembled many, shapeBecome Porous silicon particle. On the other hand, in Figure 12, observe the structure of the wall shape of thickness 5 μ m left and right.

Utilize the image information of electron microscope (SEM) to determine the average grain diameter of silicon particle. In addition, by Porous silicon grainSon is divided on radial direction on more than 50% near surface region and radial direction 50% with interior inside particles region, calculatesGo out the ratio of average grain diameter Ds separately and Di. The value of Ds/Di in an embodiment all between 0.5～1.5, but is being utilized etchingIn the comparative example 1-2 that method obtains, compared with inside particles region, the average grain diameter of the particulate near surface region diminishes, Ds/The value of Di diminishes.

Utilize ICP ICP Atomic Emission Spectrophotometer instrumentation to make the Si concentration of silicon particle and Porous silicon particle. Be all contain 80 formerSilicon more than sub-%.

Utilize mercury penetration method (JISR1655) to use 15mL liquid pool to determine the average void fraction of Porous silicon particle.

In addition, Porous silicon particle is divided on radial direction on more than 50% near surface region and radial direction50% with interior inside particles region, utilizes the image information of SEM to determine the Xs as average void fraction and Xi separately, meterCalculate the ratio of Xs and Xi. In embodiment, the value of Xs/Xi is between 0.5～1.5, but at the comparative example that utilizes etching method to obtainIn 1-2, due to compared with inside particles region, the pore structure prosperity near surface region, therefore Xs/Xi becomes large.

In addition, Figure 13 be measure the Porous silicon particle that forms embodiment 1-12 silicon particle and X-ray diffraction lightGrid picture. Owing to observing the diffraction of the crystal that comes from silicon, can obtain diffraction a little, therefore known silicon particle is by monocrystalline silicon structureBecome.

(evaluation of cycle characteristics when particle is used for to negative pole)

(i) preparation of cathode size

By the particle of embodiment or comparative example and acetylene black (Deuki Kagaku Kogyo Co., Ltd's system) respectively with 40 mass partsDrop in mixer with the ratio of 45 mass parts. Again using as styrene butadiene ribber (SBR) the 40 quality %'s of adhesiveThe sodium carboxymethylcellulose of the thickener of the viscosity of slurry is adjusted in emulsion (Japanese Zeon (strain) system, BM400B) and conduct(Daicel chemical industry (strain) system) 1 quality % solution is to be scaled 5 mass parts and to change with solid constituent with solid constituent respectivelyCalculation is that slurry is produced in the ratio mixing of 10 mass parts.

(ii) making of negative pole

Use automatic coating device to be coated on the collector body electrolysis of thick 10 μ m with the thickness of 10 μ m in prepared slurry(Furukawa electrical industry (strain) system, NC-WS) is upper for Copper Foil, after being dried at 70 DEG C, and through the thick operation of tune by stamping machine, systemProduce negative electrode for lithium ion battery.

(iii) evaluating characteristics

Be φ 20mm by negative electrode for lithium ion battery stamping-out, using metal Li to electrode with in extremely, inject by containingThere is the LiPF of 1mol/L₆Ethylene carbonate and the electrolyte that forms of the mixed solution of diethyl carbonate, form electrochemical testBattery. And the assembling of electrochemical test battery is to carry out in dew point is the glove box below-60 DEG C. Charge-discharge characteristicEvaluation is the discharge capacity after the charge/discharge by measuring first discharge capacity and 50 times circulation, calculates discharge capacitySustainment rate and carrying out. Discharge capacity calculates taking the gross weight of storing/emitting effective active material Si for the suction of lithium as benchmark. FirstFirst, under 25 DEG C of environment, under the galvanostatic conditions that current value is made as to 0.1C, charge, be reduced to 0.02V at magnitude of voltageThe time point of (using the oxidation-reduction potential with reference to utmost point Li/Li+ as 0V benchmark, below identical) stops charging. Then, at electric currentUnder the condition of value 0.1C, discharge, until be 1.5V with respect to the voltage with reference to the utmost point, determine the 0.1C initial stage appearance of dischargingAmount. And so-called 0.1C, is can be with the current value of full charging in 10 hours. Then, repeatedly carry out with the speed that discharges and recharges of 0.1CAbove-mentioned the discharging and recharging of 50 circulations. With percentage obtain repeatedly carry out 50 times circulation discharge and recharge time discharge capacity with respect at the beginning ofThe ratio of phase discharge capacity, as discharge capacity sustainment rate after 50 circulations.

[embodiment 2]

Below, the embodiment 2 relevant with the Porous silicon complex particles that contains complex element described.

(embodiment 2-1)

With the ratio of Si:Fe:Mg=25:5:70 (atom %) by Si powder (block purity is more than 95.0%), iron powder(granular: 2mm, purity: more than 99.999%) and magnesium dust (powder purity: more than 98.0%) coordinate, by it in argon gas atmosphereIn at 1120 DEG C fusing. ,, use single roll cast-rolling mill to produce thickness of slab 40 μ m's with the cooling velocity chilling of 800K/s thereafterSilicon alloy strip processed (operation (a)). It is flooded after 1 minute in the bismuth liquation of 500 DEG C, immediately chilling in argon gas. UtilizeThis processing, the silicon compound particle that obtains silicon particle, formed by Si-Fe alloy, the second-phase being formed by Mg-Bi alloy or BiComplex (operation (b)). This complex is flooded 5 minutes in nitric acid 20% aqueous solution, obtain Porous silicon complex grainSon (operation (c)).

(embodiment 2-2～2-8,2-10,2-11)

Creating conditions of each embodiment, comparative example is summarised in table 6. Embodiment 2-2～2-8,2-10,2-11 existThe cooperation ratio of the intermediate alloy element shown in table 6, complex element, each element etc. is created conditions down, other and embodimentThe method of 2-1 obtains Porous silicon complex in the same manner. And, in embodiment 2-4, cannot form the silicon of continuous thin ribbon shapedAlloy disconnects in the time of 1～2cm, is therefore the silicon alloy of foil-like. So-called φ in the wire silicon intermediate alloy of embodiment 2-5100 μ m, the diameter that refers to the intermediate alloy of wire is 100 μ m. Also identical in embodiment 2-8.

(embodiment 2-9)

With the ratio of Si:V:P=40:1:59 (atom %), Si powder, vanadium powder end and phosphor powder are coordinated, by it at argon gasFusing at 1439 DEG C in atmosphere. ,, use gas atomization to produce average grain diameter with the cooling velocity chilling of 800K/s thereafterThe granular silicon alloy (operation (a)) of 40 μ m. It is flooded after 1 minute in the cadmium liquation of 750 DEG C, anxious in argon gas immediatelyCold. Utilize this processing, the silicon compound particle that obtain silicon particle, is formed by the alloy of Si and V and by P-Cd alloy or Cd structureThe complex (operation (b)) of the second-phase becoming. This complex is flooded 5 minutes in nitric acid 20% aqueous solution, obtain PorousSilicon complex particles (operation (c)). In addition, the so-called φ 40 μ m in particulate master alloy, refer to the average of particulate master alloyParticle diameter is 40 μ m.

(embodiment 2-12)

Ratio with Si:Mg=31:69 (atom %) coordinates silicon with magnesium, it is melted in argon gas atmosphere. Exist, thereafterCooling in mold, produce the square big or small silicon alloy ingot processed of 5mm. By it in the bismuth liquation of the arsenic that contains 1 atom %Flood after 1 minute chilling in argon gas immediately. Utilize this processing, the silicon compound that obtains silicon particle, formed by Si-As alloyThe complex of particle and the second-phase that formed by Mg-Bi alloy or Bi. This complex is flooded in nitric acid 20% aqueous solution50 minutes, obtain Porous silicon complex particles.

(embodiment 2-13～2-16)

Embodiment 2-13～2-16 the cooperation ratio of the intermediate alloy element shown in table 6, each element, etc. manufacture barUnder part, the method for other and embodiment 2-12 obtains Porous silicon complex particles in the same manner. And, embodiment 2-13,2-15,2-16 uses cooling of water-cooled to improve cooling velocity.

(comparative example 2-1)

With the ratio of Si:Fe:Mg=55:1:44 (atom %), Si powder, iron powder and magnesium dust are coordinated, by it veryFusing at 1195 DEG C in empty stove. , use copper billet casting, produce the square silicon alloy of 5mm with the cooling velocity of 1K/s thereafterClamp dog. It is flooded after 200 minutes in the bismuth liquation of 930 DEG C, immediately chilling in argon gas. By this 2 phase complex at nitric acidIn 20% aqueous solution, flood 50 minutes. This comparative example does not meet a ÷ (a+Y) × 100≤[the Si maximum level] of formula (2).

(comparative example 2-2)

With the ratio of Si:Fe:Mg=25:11:64 (atom %), Si powder, iron powder and magnesium dust are coordinated, by itsFusing at 1105 DEG C in vacuum drying oven. , use copper billet casting, produce the square silicon of 5mm with the cooling velocity of 1K/s and close thereafterGold clamp dog. It is flooded after 10 minutes in the bismuth liquation of 410 DEG C, immediately chilling in argon gas. By this 2 phase complex at nitric acidIn 20% aqueous solution, flood 50 minutes. This comparative example does not meet 10≤a ÷ (a+Y) × 100 of formula (2).

(comparative example 2-3)

With the ratio of Si:Mg=24:76 (atom %), Si powder and magnesium dust are coordinated, by its in vacuum drying oven 1095Fusing at DEG C. , use water-cooled copper block casting, produce the silicon alloy strip processed of 300 μ m with the cooling velocity of 800K/s thereafter. WillIt floods after 250 minutes in the alloy baths of the bismuth 85 atom % of 895 DEG C and nickel 15 atom %, chilling in argon gas immediately. WillThis 2 phase complex floods 50 minutes in nitric acid 20% aqueous solution. Independent complex element in the alloy baths of this comparative exampleConcentration be greater than 10 atom %.

(comparative example 2-4)

With the ratio of Si:Fe=90:10 (atom %), Si powder and iron powder are coordinated, by its in vacuum drying oven 1390Fusing at DEG C. , use single roll cast-rolling mill cooling velocity chilling with 110K/s, produce silicon alloy foliation sheet thereafter. By itsIn hydrofluoric acid nitric acid, flood after 10 minutes washing.

(comparative example 2-5)

Ratio with Si:Fe=66:34 (atom %) coordinates Si powder with iron powder, by its in vacuum drying oven 1250Fusing at DEG C. , utilize gas atomization carry out quench solidification, produce FeSi thereafter₂Intermetallic compound. After being sieved, reclaimThe particle of particle diameter distribution 1～10 μ m. By silicon particle (SIE23PB, the high-purity chemical research institute of this particle and average grain diameter 5 μ mSystem) mix with 2:1, use styrene butadiene ribber (SBR) granulation as adhesive.

[evaluation]

Evaluation result is summarised in table 7. And, embodiment 2-13 to 2-16, comparative example 2-3 because silicon particle is large,Therefore use the particle diminishing after pulverizing with mortar to carry out evaluating characteristics. For example, the Porous silicon complex of embodiment 2-13The average grain diameter of particleMean, the Porous silicon complex particles that is 130 μ m by original average grain diameter is pulverizedAfter obtain the Porous silicon complex particles that average grain diameter is 33 μ m.

[table 6]

[table 7]

As shown in table 7, the average grain diameter x of the silicon particle of each embodiment is in 2nm～2 μ m, the standard of the particle diameter of silicon particleDeviations is 1～500nm, and (σ/x) is 0.01～0.5 for the ratio of average x and standard deviation. In addition, in each embodiment, on average the longestDiameter a is 1.1～50 with the average ratio (a/b) of the shortest diameter b. And then, the linking part of silicon particle and adjacent silicon particle thickDegree is below 80% with the ratio (link thickness ratio) of the diameter of a larger side's of adjacent silicon particle silicon particle.

In each embodiment, owing to being that manufacture method by having utilized dealloying (dealloying) is made satisfiedThe Porous silicon complex particles of each important document of recording in technical scheme 9, therefore capacity dimension after the circulation of 50 times in each embodimentHoldup is high, and cycle characteristics is good. Can infer, because the particle diameter of silicon particle is even, the therefore active material in the time discharging and rechargingWhen expansion/contraction, do not have stress to the inhomogeneous position of particle diameter concentrate, thereby cycle characteristics is significantly improved.

Each embodiment is compared with each comparative example, and after 50 circulations, capacity dimension holdup is high, by repeatedly causing of discharging and rechargingThe ratio of reduction of discharge capacity little, therefore can estimate that the life-span of battery is long.

In addition, in each embodiment, because negative electrode active material is the porous with three-dimensional mesh structure or continuous spaceTherefore matter silicon complex particles, even if produce the expansion/contraction that the alloying by Li and Si/de-alloying causes while discharging and rechargingVolume Changes, can not produce breaking or micronizing of silicon complex particles yet, discharge capacity sustainment rate is high.

If compared in more detail,, in comparative example 2-1, in the time that intermediate alloy is made, as primary crystal, crystallization goes out pure Si, entersAnd generate eutectic structure (Si and Mg latter stage solidifying₂Si). This primary crystal Si is the thick particle that reaches 10 μ m left and right. Even willIt is impregnated in bismuth liquation, also can not make it miniaturization, also can be remaining with original form after etching work procedure. Thus canThink, repeatedly carrying out the intrusion of Li/while emitting, cannot follow by discharge and recharge=Li and Si with the Si simple substance headed by thick SiThe Volume Changes of the expansion/contraction due to alloying/de-alloying, breaks or avalanche, loses current collection passage or electrode meritIt is many that the ratio of energy becomes, the lifetime of battery.

In comparative example 2-2, because to be compared to mutually the amount of iron of complex element many with silicon, most silicon forms silicationThing, therefore discharge capacity is little.

In comparative example 2-3, owing to adding to, the amount of the Ni as complex element in flooded liquation is many, large portionThe silicon dividing forms silicide, and therefore discharge capacity is little.

Figure 24 is the surperficial SEM photo of the Porous silicon particle of comparative example 2-4. Can observe a lot of particle diameter 1～The particle of 2 μ m.

In comparative example 2-4, because the etching that utilizes hydrofluoric acid or nitric acid forms pore structure, therefore at particle central partBe formed with the position that does not form pore. Can think, the part of this core cannot be followed the Volume Changes causing by discharging and recharging, circulationCharacteristic is poor.

In comparative example 2-5, owing to being the simple particle without pore structure, therefore can think, cannot follow byDischarge and recharge the Volume Changes causing, cycle characteristics is poor.

(evaluation of shape of particle)

Use scanning infiltration type electron microscope (NEC's system, JEM3100FEF) to carry out Porous silicon complexThe observation of the shape of particle of particle. In Figure 14, express the surperficial SEM photo of the particle of embodiment 2-1, Tu15Zhong, representsGo out the SEM photo in the cross section of the inside particles of embodiment 2-1, Tu16Zhong, particle surperficial of expressing embodiment 2-1SEM photo. In Figure 14, Figure 15, observe, the silicon particle of particle diameter 20nm～50nm be bonded with each other and assembled many, form porousMatter silicon complex particles. In addition, in Figure 14 and Figure 15, observe, aspect the particle diameter of voidage, silicon particle, there is no large difference.In Figure 16, observe the appearance that has engaged little silicon particle on the particle of large silicide.

Figure 17 is the X-ray diffraction grating image that forms the silicon particle of silicon complex particles. Observe the crystal that comes from siliconHot spot, known silicon particle is monocrystalline.

Utilize the image information of electron microscope (SEM) to determine the average grain diameter of silicon particle and silicon compound particle. WillPorous silicon complex particles is divided on radial direction on more than 50% near surface region and radial direction 50% with interiorInside particles region, according to SEM photo separately, obtains average grain diameter Ds and Di separately, calculates their ratio. Ds/DiValue in an embodiment all between 0.5～1.5, but in the comparative example 2-4 that utilizes etching method to obtain, with inside particlesRegion is compared, and the average grain diameter of the particulate near surface region is little, and the value of Ds/Di diminishes. Putting down of Porous silicon complex particlesAll particle diameter has used the aforesaid observation of SEM and the method for DLS of simultaneously using.

Utilize ICP ICP Atomic Emission Spectrophotometer instrumentation make the Si of the Si concentration of silicon particle, Porous silicon complex particles and answerThe concentration of fit element etc. In embodiment arbitrarily, silicon particle all contains silicon more than 80 atom %.

Utilize mercury penetration method (JISR1655) to use 15mL liquid pool to determine the average of Porous silicon complex particlesVoidage.

In addition, Porous silicon complex particles is divided into more than 50% near surface region and radius side on radial directionUpwards 50% with interior inside particles region, with the position arbitrarily in surface scan type electron microscope observation regional,Obtain the Xs as average void fraction and Xi separately, calculate the ratio of Xs and Xi. In an embodiment the value of Xs/Xi 0.5～Between 1.5, but in the comparative example 2-4 that utilizes etching method to obtain, compared with inside particles region, due near surface districtThe pore structure prosperity in territory, therefore Xs/Xi becomes large.

Except calculating and put as benchmark using silicide and the gross weight of storing/emitting effective active material Si for the suction of lithiumBeyond capacitance, evaluate in the same manner cycle characteristics with embodiment 1.

[embodiment 3]

(embodiment 3-1)

Use the process identical with embodiment 1 and change the various conditions of operation (a) to (c), change silicon alloy particulateParticle diameter, shape, distribution. Particularly, changed dipping temperature, the time in operation (b). In addition, as a comparative example, to operation(b) bath of molten metal has applied mechanical agitation (agitation energy) or vibration (amplitude: 1mm × 60Hz). These conditions are representedIn table 8. In addition, by utilizing Porous silicon particle that this method for making obtains and silicon particle and embodiment 1 to comment in the same mannerValency, is shown in the result of gained in table 9.

[table 8]

[table 9]

Rear capacity dimension holdup in each comparative example, circulate for 50 times lower than 80%, but in each embodiment, after 50 circulations, holdAmount sustainment rate exceedes 80%.

The average grain diameter x of the silicon particle of each embodiment is in 2nm～2 μ m, and the standard deviation of the particle diameter of silicon particle is 1～500nm, (σ/x) is 0.01～0.5 for the ratio of average x and standard deviation. In addition, in each embodiment, average longest diameter a is with flatAll the ratio (a/b) of the shortest diameter b is 1.1～50. And then the thickness of the linking part of silicon particle and adjacent silicon particle is with adjacentThe ratio (link thickness ratio) of the diameter of a larger side's of silicon particle silicon particle is below 80%.

Figure 18 is the SEM photo of the Porous silicon particle of embodiment 3-7. The known silicon of having assembled multiple diameter 30nm left and rightParticulate.

In addition, Figure 19 is the TEM photo that forms the silicon particle of the Porous silicon particle of embodiment 3-7. Silicon particle averageParticle diameter x is 28.6nm, and standard deviation is 5.3nm, σ/x=0.19. Known particle diameter is even, and between silicon particle with thick connectionEngage.

Figure 20 is the size distribution that forms the silicon particle of the Porous silicon particle of embodiment 3-7. Silicon particle is one by oneFlat spherical particle is these particles are engaged and form therefore known distribution Non-Gaussian Distribution.

Figure 21 is the TEM photo that forms the silicon particle of the Porous silicon particle of embodiment 3-8, and upper left is the observation in TEMSEAD picture in region. In TEM photo, in a silicon particle, there is no crystal boundary, known is monocrystalline. In addition, in choosingIn district's electronic diffraction picture, observe the hot spot of the crystal that comes from silicon, still known silicon particle is monocrystalline. In addition, this silicon particleForm flat spherically, major axis footpath is 36nm, and short shaft diameter is 27nm. In addition even if get the average of multiple silicon particles, be also average,The shortest diameter a is 36nm, and on average the shortest diameter b is 27nm, a/b=1.33.

Figure 25 is the SEM photo of the Porous silicon particle of embodiment 3-1. Observe the much silicon that is polygonal columnar growthParticulate. Average strut diameter x is 203.6nm, and standard deviation is 80.6nm, and σ/x is 0.40.

Figure 26 is the SEM photo of the Porous silicon particle of embodiment 3-2. Observe about many strut diameter 20nmBe the silicon particle of columnar growth.

Figure 27 is the SEM photo of the Porous silicon particle of comparative example 3-3. Observe many silicon particles of growing up. Average particleFootpath x is 694.0nm, and standard deviation is 231.7nm, and σ/x is 0.33. In addition, due to long-time dipping, silicon particle surperficialThe diameter of particulate is large, and it is 1.08 than Es/Ei.

Figure 28 is the microstructure photo of the intermediate alloy of embodiment 1-15.

Above, in reference to accompanying drawing, be preferred embodiment illustrated of the present invention, but the present invention alsoBe not limited to this example. Obviously, as long as those skilled in the art, just can be at the category of the disclosed technological thought of the applicationIn, expecting various modifications or fixed case, can understand, certainly also belong to technical scope of the present invention for them.

Utilizability in industry

Porous silicon complex particles of the present invention not only can, in the negative pole of lithium ion battery, can also be served as lithiumThe negative pole of ionistor, solar cell, luminescent material, wave filter materials'use.

[explanation of Reference numeral]

1 ... Porous silicon particle

3 ... silicon particle

S ... near surface region

I ... inside particles region

7 ... silicon intermediate alloy

9 ... second-phase

11 ... single roll cast-rolling mill

13 ... silicon alloy

15 ... crucible

17 ... steel roller

19 ... thin ribbon shaped silicon intermediate alloy

21 ... liquation device

23 ... liquation

25 ... submergence roller

27 ... backing roll

31 ... gas atomization device

33 ... crucible

35 ... nozzle

37 ... gas spraying machine

39 ... Powdered silicon intermediate alloy

41 ... rotating circular disk atomising device

43 ... crucible

45 ... nozzle

47 ... gas spraying machine

49 ... rotating circular disk

51 ... Powdered silicon alloy

53 ... crucible

55 ... mold

57 ... bulk silicon intermediate alloy

61 ... liquation immersion system

63 ... bulk silicon intermediate alloy

65 ... dipping cage

67 ... pushing cylinder

69 ... liquation

71 ... liquation immersion system

73 ... bulk silicon intermediate alloy

75 ... dipping cage

77 ... pushing cylinder

79 ... liquation

81 ... mechanical type mixer

83 ... gas blows plug

101 ... Porous silicon complex particles

103 ... silicon particle

105 ... silicon compound particle

S ... near surface region

I ... inside particles region

107 ... silicon intermediate alloy

109 ... second-phase

111 ... silicon intermediate alloy

Claims

1. a Porous silicon particle, is the Porous silicon particle multiple silicon particles joints to continuous space, its spyLevy and be,

The average x on particle diameter, strut diameter or the pillar limit of described silicon particle is 2nm～2 μ m,

The standard deviation on particle diameter, strut diameter or the pillar limit of described silicon particle is 1～500nm,

The ratio of described average x and described standard deviation (σ/x) is 0.01～0.5,

The average particle of the described silicon particle in the near surface region on the radial direction of described Porous silicon particle more than 50%50% average with the described silicon particle in interior inside particles region on the radial direction of footpath Ds and described Porous silicon particleThe ratio Ds/Di of particle diameter Di is 0.5～1.5.

2. Porous silicon particle according to claim 1, is characterized in that,

The shape of described silicon particle has flat spherical, cylindric or polygonal column, and average longest diameter or longest edge a are with flatAll the ratio (a/b) of the shortest diameter or minor face b is 1.1～50.

3. Porous silicon particle according to claim 1, is characterized in that,

The average grain diameter of described Porous silicon particle is 0.1 μ m～1000 μ m,

The average void fraction of described Porous silicon particle is 15～93%,

Voidage Xs near surface region on the radial direction of described Porous silicon particle more than 50% and described porousOn the radial direction of matter silicon particle, the 50% ratio Xs/Xi taking the voidage Xi in interior inside particles region is as 0.5～1.5,

Contain silicon more than 80 atom % with the ratiometer of the element except oxygen.

4. Porous silicon particle according to claim 1, is characterized in that,

By described Porous silicon particle be divided on radial direction on more than 90% near surface region S and radial direction 90% withUnder inside particles region I, the average grain diameter of described silicon particle that forms described near surface region S is made as to Es, by structureWhile becoming the average grain diameter of the described silicon particle of described inside particles region I to be made as Ei, Es/Ei is 0.01～1.0.

5. Porous silicon particle according to claim 1, is characterized in that,

Described silicon particle is to be characterised in that with the ratiometer of the element except oxygen to contain the solid of more than 80 atom % siliconSilicon particle.

6. Porous silicon particle according to claim 1, is characterized in that,

The area at the junction surface between described silicon particle is below 30% of surface area of described silicon particle.

7. Porous silicon particle according to claim 1, is characterized in that,

In the junction surface of described silicon particle and adjacent described silicon particle, the thickness at described junction surface or diameter are adjacent instituteState below 80% of diameter of a larger side's of silicon particle silicon particle,

Described junction surface is made up of crystallized silicon or Si oxide.

8. Porous silicon particle according to claim 2, is characterized in that,

Multiple described silicon particles have produced orientation,

The direction of the major axis of multiple described silicon particles all in certain direction ± 30 ° in.

9. a Porous silicon complex particles, engages multiple silicon particles and have continuous with multiple silicon compound particleThe Porous silicon complex particles in space, is characterized in that,

Described silicon compound particle contain silicon with select free As, Ba, Ca, 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, Te, Th, Ti, Tm, U, V, W, Y, Yb, Zr formThe compound of the complex element of more than one of group,

Putting down of the described silicon particle in the near surface region on the radial direction of described Porous silicon complex particles more than 50%On the radial direction of equal particle diameter Ds and described Porous silicon complex particles, 50% is micro-with the described silicon in interior inside particles regionThe ratio Ds/Di of the average grain diameter Di of grain is 0.5～1.5.

10. Porous silicon complex particles according to claim 9, is characterized in that,

11. Porous silicon complex particles according to claim 9, is characterized in that,

The average grain diameter of described Porous silicon complex particles is 0.1 μ m～1000 μ m.

12. Porous silicon complex particles according to claim 9, is characterized in that,

Described silicon particle is the solid silicon particle that contains silicon more than 80 atom % with the ratiometer of the element except oxygen.

13. Porous silicon complex particles according to claim 9, is characterized in that,

The average grain diameter of described silicon compound particle is 50nm～50 μ m,

Described silicon compound particle is to be characterised in that the silicon that contains 50～90 atom % with the ratiometer of the element except oxygenThe particle of solid silicon compound.

14. Porous silicon complex particles according to claim 9, is characterized in that,

The voidage Xs in the near surface region on the radial direction of described Porous silicon complex particles more than 50% with described inOn the radial direction of Porous silicon complex particles, the ratio Xs/Xi of the 50% voidage Xi taking interior inside particles region is as 0.5～1.5。

15. Porous silicon complex particles according to claim 9, is characterized in that,

Described Porous silicon complex particles is divided on radial direction on more than 90% near surface region S and radial directionInside particles region I below 90%, is being made as the average grain diameter of the described silicon particle that forms described near surface region SEs, when the average grain diameter of described silicon particle that forms described inside particles region I is made as to Ei, Es/Ei is 0.01～1.0.

16. Porous silicon complex particles according to claim 9, is characterized in that,

In the junction surface of described silicon particle and adjacent described silicon particle, the thickness at described junction surface or radius are adjacent instituteState below 80% of radius of a larger side's of silicon particle silicon particle,

Described junction surface is made up of crystallized silicon or Si oxide.

17. Porous silicon complex particles according to claim 10, is characterized in that,

Multiple described silicon particles have produced orientation,