TWI437746B - Non-aqueous electrolyte secondary battery - Google Patents

Description

Nonaqueous electrolyte secondary battery

The present invention relates to a nonaqueous electrolyte secondary battery, and more particularly to a nonaqueous electrolyte secondary battery having high capacity and excellent cycle characteristics.

A lithium ion secondary battery is mainly used in a portable device, and is required to have a high capacity as the size and function of the use device are reduced. However, the theoretical capacity of a carbon-based material such as artificial graphite or natural graphite of a negative electrode active material of a lithium ion secondary battery used today is 372 mAh/g, and it is not desired to increase the capacity to the above.

Therefore, it is proposed to use a metal material such as ruthenium (Si) or tin (Sn) having a larger theoretical capacity or a negative electrode thereof (for example, refer to Patent Document 1), although it attracts attention, but these materials are in the initial number. Although the degree of the secondary cycle shows a very high capacity, the micronization is caused by the expansion and contraction of the active material by repeated charge and discharge, and the negative electrode active material is detached from the current collector, and the cycle characteristics are extremely poor.

In this regard, a method of suppressing deterioration due to charge and discharge cycles by mixing a component such as Si and Sn capable of absorbing Li and a component such as Cu and Fe in which Li cannot be stored by mechanical chemical method is proposed (for example, reference) Patent Document 2).

On the other hand, as a method for producing an electrode, a film of these materials is formed on a current collector by a CVD method, a sputtering method, a vapor deposition method, or a plating method (for example, Patent Document 3). Furthermore, a method of adding a cyclic carbonate having an unsaturated bond to an electrolytic solution is proposed as a method of setting a coating film on the electrode surface formed by the method (for example, Patent Document 4).

Advanced technical literature 1

Patent literature

Patent Document 1: Japanese Patent Publication No. 07-29602

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-78999

Patent Document 3: Japanese Laid-Open Patent Publication No. 11-135115

Patent Document 4: Japanese Laid-Open Patent Publication No. 2004-171877

However, the invention described in Patent Document 2 is difficult to uniformly disperse each component at a nanometer size, and in particular, it is expected to be put into practical use as a negative electrode material, and the volume change during charging and discharging is large, and cracking easily occurs, and it is not possible to sufficiently prevent it. Deterioration of cycle characteristics.

In the invention described in Patent Document 3 and Patent Document 4, the negative electrode active material layer is formed by a CVD method, a sputtering method, a vapor deposition method, or a plating method, and deterioration of cycle characteristics can be suppressed to some extent. The thickness of the layer cannot be formed only by a thin film electrode, and it is difficult to put it into practical use because the quality of the active material is insufficient when constituting the lithium secondary battery. Furthermore, the invention described in Patent Document 4 suppresses decomposition of the electrolytic solution by forming a strong film on the surface of the active material layer of the thin film electrode, and suppresses deterioration of cycle characteristics, but forms an active material layer by a coating method. The past coated electrode cannot achieve a suppressing effect.

The present invention has been made in view of the above problems, and an object thereof is to obtain a nonaqueous electrolyte secondary battery which realizes high capacity and good cycle characteristics.

As a result of intensive studies to achieve the above object, the inventors of the present invention have found that by using a negative electrode active material mainly having a nano-size having a lithium occlusion property, micronization of the negative electrode active material can be suppressed. Further, it has been found that the first phase absorbing lithium by the transmission interface and the second phase not absorbing lithium can suppress the volume expansion of the first phase due to charge and discharge. Further, in the case where the negative electrode active material layer is formed by using the negative electrode active material having such a nanometer size in the electrode by a coating method, it is found that the electrolyte is formed on the surface of the negative electrode active material layer because the electrolyte contains an organic substance capable of reductive polymerization having an unsaturated bond. A stable film to inhibit the decomposition of the electrolyte. Then, it was finally found that the formation of such a film depends on the electronic arrangement of the substance contained in the negative electrode, and the form of the more effective and diverse negative electrode active material can be exhibited. The present invention has been completed based on these findings.

That is, the present invention provides the following invention.

(1) A nonaqueous electrolyte secondary battery characterized in that it has a positive electrode capable of occluding and releasing lithium ions, a negative electrode capable of occluding and releasing lithium ions, and an isolation disposed between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are provided in a nonaqueous electrolytic solution having lithium ion conductivity, and the negative electrode active material of the negative electrode includes a first particle containing the element X and a first element containing the element M. 2 particles, wherein the element X is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, and the element M is a transition from the 4th to the 11th. One element selected from the group consisting of metal elements, the first particle is composed of a monomer or a solid solution of the element X, and the second particle is composed of a monomer or a compound of the element M. The electrolyte solution contains an organic substance having an unsaturated bond in the molecule and capable of being reduced in polymerization.

(2) The nonaqueous electrolyte secondary battery according to the above aspect, wherein the first particles have an average particle diameter of 2 nm to 500 nm, and the second particles have an average particle diameter of 2 nm to 10 μm.

(3) The nonaqueous electrolyte secondary battery according to the above aspect, wherein the surface of the first particle is within 1 μm from the surface of the second particle.

(4) A non-hydrolyzable electrolyte secondary battery comprising: a positive electrode capable of occluding and releasing lithium ions; a negative electrode capable of occluding and releasing lithium ions; and an isolation disposed between the positive electrode and the negative electrode The positive electrode, the negative electrode, and the separator are provided in a nonaqueous electrolytic solution having lithium ion conductivity, and the negative electrode active material of the negative electrode is composed of nanosized particles including an element X and an element M. The element X is one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, and the element M is a transition metal element of Groups 4 to 11. At least one element selected from the group consisting of the monomer having at least the element X or the first phase of the solid solution, and the monomer of the element M or the second phase of the compound. The electrolytic solution contains an organic substance having an unsaturated bond in the molecule and capable of being reduced in polymerization.

(5) The non-hydrolyzed electrolyte secondary battery according to the above aspect, wherein the first phase and the second phase of the nanosized particle are exposed to an outer surface and are bonded to each other through the interface. The outer surface of the phase is generally spherical.

(6) The non-hydrolyzed electrolyte secondary battery according to the above (4), wherein the nano-sized particles have an average particle diameter of from 2 nm to 500 nm.

(7) The non-hydrolyzed electrolyte secondary battery according to the above (4), wherein the nanosized particle system further contains an element M' which is composed of Cu, Fe, Co, Ni, Ca, Sc, Ti, V, Selected from the group consisting of Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanides (excluding Ce and Pm), Hf, Ta, W, Re, Os, and Ir At least one element of the element M' is an element different from the type of the element M constituting the second phase; and further has a monomer or a further second phase of the compound of the element M'.

(8) The non-hydrolyzed electrolyte secondary battery according to the above aspect, wherein the nano-sized particle system further contains an element X' which is composed of Si, Sn, Al, Pb, Sb, Bi, Ge, In, At least one element selected from the group consisting of Zn, and further having a monomer of the aforementioned element X' or a third phase of a solid solution.

(9) The non-hydrolyzed electrolyte secondary battery according to the above aspect, wherein the third phase-based transmission interface is joined to at least one of the first phase and the second phase.

(10) The non-hydrolyzed electrolyte secondary battery according to (1), wherein the first particle is a nano-sized particle described in (4).

(11) The non-hydrolyzed electrolyte secondary battery according to the above (1) or (4), wherein the organic compound having an unsaturated bond in the molecule and capable of being reductively polymerized is a fluoroethylene carbonate or a vinylene carbonate. At least one selected from the group consisting of its derivatives and ethylene carbonate.

(12) The non-hydrolyzed electrolyte secondary battery according to the above (11), wherein the amount of the organic substance having an unsaturated bond in the molecule and capable of being reductively polymerized is 0.1% by weight to 10% by weight based on the weight of the electrolyte.

(13) The non-hydrolyzed electrolyte secondary battery according to the above aspect, wherein the negative electrode is coated with a coating liquid containing at least a negative electrode active material, a conductive material, and an adhesive material, and then dried. form.

According to the present invention, a nonaqueous electrolyte secondary battery which realizes high capacity and good cycle characteristics can be obtained.

Form of implementing the invention

Embodiments of the present invention will be described in detail below based on the drawings.

(1. Composition of nonaqueous electrolyte secondary battery)

First, a nonaqueous electrolyte secondary battery according to an embodiment of the present invention will be described with reference to Fig. 1 .

The nonaqueous electrolyte secondary battery 1 of the present invention has a positive electrode 3 capable of occluding and releasing lithium ions, a negative electrode 5 capable of occluding and releasing lithium ions, and a separator 7 disposed between the positive electrode 3 and the negative electrode 5, and The positive electrode 3, the negative electrode 5, and the separator 7 are provided in the nonaqueous electrolytic solution 8 having lithium ion conductivity.

The present invention is characterized in that the negative electrode 5 is used as an active material, and a particle composed of an element of a lithium ion having a simple characteristic is used, and the electrolytic solution 8 used for the negative electrode contains an unsaturated bond in the molecule and can Reductive polymerization of organic matter.

(2. Negative electrode)

(2-1. Configuration of Negative Electrode Active Material A of First Embodiment)

On the other hand, the first embodiment of the negative electrode active material of the present invention will be described with reference to Fig. 2 . 2 is a schematic view showing a configuration example of a negative electrode active material including a first particle 9 containing an element X and a second particle 10 containing an element M.

The first particle 9 may be formed of a monomer of the element X or a solid solution containing the element X as a main component. Here, the element X is one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn. Further, the element X "as a main component" means that the ratio of the element X is 50 atom% or more, and more preferably 70 atom% or more. In the case where the first particle 9 is a solid solution of the element X, the element X and the element forming the solid solution may be selected from the elements indicated in the group of the aforementioned elements X, and the other may be selected. Since the element X is an element which easily absorbs lithium, the first particle 9 can also store lithium. Further, the first particles 9 can be substantially spherical, and the other aspects are described in detail later.

Further, in the first particle 9, it is preferable that the element X is Si from the viewpoint of the storage property of lithium ions. In this case, the conductivity of the crucible can be improved by adding phosphorus or boron to the crucible. Indium or gallium can be used instead of phosphorus, and arsenic can be used instead of boron. By increasing the conductivity of the first particles 9, the internal resistance of the negative electrode 5 is reduced, and a large current can be made to flow, and good high-efficiency characteristics can be exhibited.

The second particles 10 may be formed of a monomer of the element M or a compound containing the element M as a main component. Here, the element M is at least one element selected from the group consisting of transition metal elements of Groups 4 to 11 of the periodic table, for example, a stable element among the transition metal elements of Groups 4 to 11, specific There are Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Au, and the like. These elements M are elements that do not readily absorb lithium. The element which forms a compound with the element M is not particularly limited, and may be the aforementioned element X. The second particle 10 has almost no lithium occlusion characteristics, and the lithium occlusion property can be adjusted by the ratio of the element M and the element forming the compound. Further, the compound may contain various alloys, intermetallic compounds, oxides, and the like.

Next, in the present invention, the second particles 10 are formed of a monomer or a compound of the element M, and two or more electrons are present in the d electron domain. For example, the outermost electrons of Ti, Fe, and Ni are configured as Ti:3d[2]4S[2], Fe:3d[6]4S[2], Ni:3d[8]4S[2], and d-electrons There are 2, 6, and 8 electrons in the orbital domain. By the presence of a plurality of d electrons in the negative electrode active material, it is considered that the non-aqueous electrolyte contained in the non-aqueous electrolyte solution 8 to be described later has an unsaturated bond and can be reduced and polymerized. The organic substance is polymerized to promote the formation of a film for protecting the negative electrode 5. Further, in the case where, for example, Ti is used as the element M, the case where Fe or Ni is used can confirm that the formation of the coating film is promoted, and it is conceivable that the number of electrons in the d electron domain is large.

In the negative electrode active material of the present invention, the first particles 9 and the second particles 10 are arranged such that the distance between the surfaces of the first particles 9 and the second particles 10 which are closest to each other is 1 μm as shown by A in FIG. 2 . Within. Within 1 μm of the distance A, the range in which the interaction between the electrons at the interface between the first particle 9 and the second particle 10 is reachable is a distance around the thickness of the electric double layer. When lithium is stored in the element X of the first particle 9, electrons are supplied to the element M of the second particle 10, and the non-aqueous electrolyte solution 8 is contained in the molecule and has an unsaturated bond, and can be reduced and polymerized. Polymerization of organic matter. Further, when the distance between the first particles and the second particles is within 1 μm, the first particles are adsorbed on the first particles in addition to the reduction product formed on the surface of the first particles, and the more stable reduction products generated by the second particles are adsorbed on the first particles. On the surface, decomposition of the electrolyte is suppressed by coating the surface.

Further, the average particle diameter of the first particles 9 is preferably from 2 nm to 500 nm, more preferably from 2 nm to 300 nm, even more preferably from 50 nm to 200 nm. According to Hall-Petch's law, the yield stress is high because of the small particle size. If the average particle size of the nano-sized particles is about 2 nm to 500 nm, the particle size and yield stress are large, and it is not easy to be charged and discharged. Chemical. Further, when the average particle diameter is less than 2 nm, it is difficult to use the nanoparticles after the synthesis of the nanoparticles, and if the average particle diameter is more than 500 nm, the particle size is too large, and sufficient yield stress cannot be obtained, which is not preferable.

The second particle 10 on the other side may have an influence on the micronization, and may have an average particle diameter of 2 nm to 10 μm. The lower limit of 2 nm is the same as that of the first particle 9 described above, and is a target value which is not difficult to use, and the upper limit of 10 μm is caused by the unevenness of the active material when the electrode active material is applied to the current collector. The reason for the reduction in cycle characteristics. In addition, when the second particles 10 are excessively large, the surface area per unit weight is reduced, and the catalytic action is also reduced. In order to obtain an effect, a large amount of the second particles 10 is required, and the entire battery is caused. From the viewpoint of the weight increase, the particle size of the second particles 10 is preferably small.

In the negative electrode 5 of the present invention, the ratio of the second particles 10 to the first particles 9 can be arbitrarily set within a range in which the desired lithium storage amount can be secured by the first particles 9 as an approximate target. The number of atoms of X constituting the first particle 9 is preferably 1% to 30%, and more preferably 7% to 10%. When the atomic ratio is less than 1%, the effect of forming a coating film on the surface of the negative electrode and the effect of suppressing the volume change of the negative electrode attached to the charge and discharge cannot be obtained. If the number of atoms is more than 30%, it is less preferable because it is impossible to ensure a sufficient lithium storage amount.

(2-2. Effect of negative electrode active material A)

According to the negative electrode of the first embodiment, the second particles 10 which do not store lithium are contained in addition to the first particles 9 which retain lithium, and the second particles 10 which do not absorb lithium can be used in the negative electrode active material layer by the catalytic action of the second particles 10 The surface is effectively formed into a stable coating film which has an unsaturated bond in the molecule and which can reduce the polymerization of the organic substance contained in the non-aqueous electrolyte solution 8 to be described later, and stabilizes the negative electrode active material to prevent decomposition of the electrolyte material. A negative electrode having excellent cycle characteristics was obtained.

In addition, in the case of the second particle 10 including the element M having high conductivity, the first particle 9 having low conductivity is used as the negative electrode active material, and the conductivity of the entire negative electrode 5 is greatly increased. In other words, even if the conductive auxiliary agent is small, the conductive negative electrode active material is provided, and a high-capacity electrode can be formed, and a negative electrode active material having high efficiency characteristics can be obtained. In particular, by using a metal element such as Fe or Cu having high conductivity as the second particle 10, a negative electrode active material having excellent conductivity can be obtained as compared with the case of only the nanoparticle.

Further, as the negative electrode active material, the second particles are contained in addition to the first particles 9, and the lithium is occluded with respect to the first particles 9 to expand the volume, and the second particles 10 do not store lithium, thereby suppressing the entire negative electrode. Volume change. Therefore, even if lithium is stored, the distortion accompanying the volume expansion of the negative electrode can be alleviated, and the decrease in the discharge capacity at the time of suppressing the cycle characteristics can be suppressed.

(2-3. Configuration of Negative Electrode Active Material B of Second Embodiment)

Next, a second embodiment of the negative electrode active material of the present invention will be described. Fig. 3 is a schematic cross-sectional view showing the nanosized particle 11 constituting the negative electrode active material of the negative electrode 5 of the present invention. The nanosized particle 11 contains an element X and an element M.

Similarly to the first embodiment described above, the element X is one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn. Element X is easy to absorb the elements of lithium.

And the element M is at least one element selected from the group consisting of transition metal elements of Groups 4 to 11, for example, a stable element among the transition metal elements of Groups 4 to 11, specifically Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Au, and the like. These elements M are elements that do not readily absorb lithium.

On the other hand, the nanosized particle 11 of the present invention has at least the first phase 13 and the second phase 15.

The first phase 13 may be a monomer of the element X or a solid solution containing Si as a main component. Further, the first phase 13 may be crystalline or amorphous. The element X is other than the element indicated in the group forming the solid solution element selectable element X. This first phase 13 can store lithium. After the primary phase 13 is accommodating lithium for primary alloying, lithium is de-alloyed to become amorphous.

The second phase 15 may be a monomer of the element M or a compound containing the element M as a main component. This second phase 15 system hardly occludes lithium. Further, as described above, the element M has two or more electrons in the d electron domain, and the formation of the film for protecting the negative electrode 5 is promoted, and the cycle characteristics can be improved.

When the element X and the element M are a combination of compounds, the second phase 15 may be formed of MX _Y or the like of the compound of the element X and the element M. On the other hand, element X and element M In the case where a combination of compounds cannot be formed, the second phase 15 may be a monomer or a solid solution of the element M.

For example, in the case where the element X is Si and the element M is Cu, the second phase 15 may be formed of a copper bismuth compound of the element M and the compound of the element X. For example, in the case where the element X is Si and the element M is Ag or Au, the second phase 15 may be formed by a monomer of the element M or a solid solution containing the element M as a main component.

In the case where the element X is Si, Si and the element M can form a compound represented by MX _Y (1 < Y ≦ 3). Such a compound may, for example, be specifically FeSi ₂ , CoSi ₂ , or NiSi ₂ (Y=2), Rh ₃ Si ₄ (Y=1.33), Ru ₂ Si ₃ (Y=1.5), or Sr ₃ Si ₅ ( Y = 1.67), Mn ₄ Si ₇ or Tc ₄ Si ₇ (Y = 1.75), IrSi ₃ (Y = 3), and the like. Here, the atomic ratio of the element M occupying the total of Si and the element M is preferably 0.01 to 25%. When the atomic ratio is 0.01 to 25%, when the nanosized particle 11 is used as a negative electrode active material, both cycle characteristics and high capacity can be achieved. On the other hand, when it is less than 0.01%, the volume change of the nanosized particle 11 when lithium is stored cannot be suppressed, and if it exceeds 25%, the advantage of high capacity will especially disappear.

On the other hand, as shown in FIG. 3, the first-sized particles 13 and the second phase 15 are exposed to the outer surface of the nano-sized particles 11, and are bonded to each other through the interface. The interface between the first phase 13 and the second phase 15 shows a plane or a curved surface. Moreover, the interface can also be stepped. The outer surface of the first phase 13 is substantially spherical. The interface shape of the joint portion between the first phase 13 and the second phase 15 is circular or even elliptical. By the presence of the second phase 15 in which the lithium is not stored in the first phase 13 which is expanded by the occlusion of lithium, the expansion of the first phase 13 due to lithium occlusion can be suppressed.

Further, the outer surface of the first phase 13 is substantially spherical, and the surface of the first phase 13 other than the interface between the first phase 13 and the second phase 15 is formed by a substantially smooth curved surface, in other words, It means that the contact between the first phase 13 and the second phase 15 is first removed, and the first phase 13 is spherical or even elliptical. The vocabulary performance of a ball or even an elliptical ball does not mean a geometrically rigid sphere and an elliptical sphere. It is a shape different from the shape of a shape having an angle on the surface as represented by the shape of the particles formed by the crushing method.

Further, as shown in FIG. 3(b), the nano-sized particles 15 of the element M or the second phase 15 of the compound may be dispersed in the first phase 13. The second phase 15 is covered by the first phase 13. The second phase 15 is the same as the second phase 15 exposed to the outer surface, and hardly occludes lithium. Further, as shown in FIG. 3(c), a part of the second phase 15 covered by the first phase 13 may be exposed on the surface. That is to say, it is not necessary that all of the periphery of the second phase 15 is covered with the first phase 13, and the first phase 13 may cover only a part of the periphery of the second phase 15.

Further, in FIG. 3(b), although the plurality of second phases 15 are dispersed in the first phase 13, a single second phase 15 may be coated.

As shown in Fig. 4(a), the second phase 15' has a polyhedral shape due to the influence of the stability of the crystal of the monomer or compound of the element M.

Further, as in the case of the nano-sized particles 11 shown in FIG. 4(b), a plurality of second phases 15 may be provided in the first phase 13. For example, in the production process of particles, when the ratio of the element M is small, and the frequency of collision between the elements M in the gas state or the liquid state is small, the relationship between the melting point of the first phase 13 and the second phase 15 is The second phase 15 is considered to be dispersed in the surface of the first phase 13 due to the influence of the cooling rate and the like.

When the plurality of second phases 15 are provided in the first phase 13, the area of the interface between the first phase 13 and the second phase 15 is increased, and the expansion and contraction of the first phase 13 can be further suppressed. Further, since the second phase 15 is higher in electrical conductivity than the first phase 13, the second phase 15 can promote the movement of electrons, and the nanosized particle 11 has a plurality of collecting points in each of the nanosized particles 11. Therefore, the nanosized particle 11 having a plurality of second phases 15 is a negative electrode material having a high powder conductivity, and the conductive auxiliary agent can be reduced, and a high capacity negative electrode can be formed. Further, a negative electrode having high efficiency and excellent characteristics can be obtained.

In the case where two or more elements selected from the group of the selectable elements M are used as the element M, the other element M is a solid solution or a compound which is included in the compound of one element M and the element X. 2 phase 15 in. In other words, even in the case where the nanosized particles include two or more elements selected from the group of the selectable elements M, there is a case where the other second phase 19 is not formed as in the element M described later. . For example, in the case where the element X is Si, one element M is Ni, and the other element M is Fe, Fe is present in the NiSi ₂ as a solid solution. Further, in the case of observation by EDS, there is a case where the distribution of Ni is substantially the same as the distribution of Fe, and another element M may be uniformly contained in the second phase 15, or may be partially contained.

Further, the nano-sized particles may contain the element M' in addition to the element M. The element M' is composed of Cu, Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanides (Ce and Pm). At least one element selected from the group consisting of Hf, Ta, W, Re, Os, and Ir is an element different from the element M constituting the second phase.

The nanosized particle 17 shown in Fig. 5(a) contains the element M and the element M', and has a second phase 19 in addition to the monomer of the element M or the second phase 15 of the compound. For example, the first phase 13 has a second phase 15 at one end and another second phase 19 at the other end, and the nano-sized particles 17 may have a shape in which two small balls are joined to the surface of the large sphere. In the monomer or compound of the second phase 19 element M', almost no lithium is occluded in the same manner as the second phase 15. Further, the nanosized particle 17 may contain a solid solution (not shown) composed of the element M and the element M'. For example, the second phase 15 is a compound of Si and Fe, the other second phase 19 is a compound of Si and Co, and the solid solution formed by the element M and the element M' is a solid solution of Fe and Co. Situation, etc.

Further, as shown in FIG. 5(b), the monomer of the element M or the second phase 15 of the compound, and the monomer of the element M' or the other second phase 19 of the compound may be dispersed in the first phase 13. . Further, although Figs. 5(a) and 5(b) show an example in which two types of elements are selected from the group of elements of the selectable element M and the element M', three or more elements may be selected.

In the case where two or more elements are selected from the group of the element M and the element M′ as described above, the group of the element M and the element M′ is the total of the elements of the group of the element X and the element M and the element M′. The atomic ratio of the total of the elements is preferably from 0.01 to 30%.

Further, in the present invention, it is preferable that the first phase 13 is mainly crystalline ruthenium and the second phase 15 is crystalline ruthenium. Further, the first phase 13 is more preferably Si added with phosphorus or boron. The conductivity of germanium can be improved by the addition of phosphorus or boron. Indium or gallium can be used instead of phosphorus, and arsenic can be used instead of boron. By increasing the conductivity between the first phase 13, the internal resistance of the negative electrode using such nano-sized particles is small, and a large current can be flowed, thereby having excellent high-efficiency characteristics.

In the present invention, the average particle diameter of the nano-sized particles 11 and 17 and 21 described later is preferably 2 to 500 nm, more preferably 50 to 200 nm. According to Hall-Page's law, the yield stress is high because the particle size is small, and if the average particle size of the nano-sized particles is about 2 to 500 nm, the particle size is sufficiently small, the yield stress is sufficiently large, and the powder is not easily charged and discharged. Chemical. Further, when the average particle diameter is less than 2 nm, it is difficult to use the nanoparticles after the synthesis of the nanoparticles, and if the average particle diameter is more than 500 nm, the particle size is too large and the yield stress is insufficient.

Further, since the fine particles are usually aggregated, the average particle diameter of the nanoparticles of the size refers to the average particle diameter of the primary particles. The measurement of the particles is combined with the image information of the electron microscope (SEM) and the volume-based median diameter of the dynamic light scattering photometer (DLS). In the average particle size, the particle shape can be confirmed by SEM image, and the particle size can be obtained by image analysis (for example, "A-Jun" trademark of Asahi Kasei Engineering Co., Ltd.), and the particles are dispersed in a solvent and DLS (for example, manufactured by Otsuka Electronics Co., Ltd.). DLS-8000) Determination and the like. When the fine particles are sufficiently dispersed without being agglutinated, substantially the same measurement results can be obtained by SEM and DLS. Further, the shape of the nano-sized particles is also the same in the case of a highly developed structural shape such as acetylene black. Here, the average particle diameter is defined by the primary particle diameter, and the average particle diameter can be obtained by image analysis of the SEM photograph.

Further, the outermost surface of the nano-sized particles 11 or 17 may also be bonded to oxygen. If the nano-sized particles are taken out in the air, the oxygen in the air reacts with the elements on the surface of the nano-sized particles. In other words, the outermost surface of the nanosized particle 11 or 17 may have an amorphous layer having a thickness of about 0.5 to 15 nm, and may have an oxide film layer particularly when the first phase is mainly a crystalline germanium.

(2-4. Effect of negative electrode active material B)

According to the second embodiment, since the first phase 13 in which lithium is stored still has the second phase 15 including the element M, the catalytic action of the second phase 15 can be utilized in the same manner as in the first embodiment. The surface of the negative electrode active material layer is effective for forming a stable coating film of an organic substance, thereby preventing decomposition of the electrolyte material and improving cycle characteristics.

Further, although the first phase 13 absorbs lithium as a volume, the second phase 15 does not store lithium, and the expansion of the first phase 13 that is in contact with the second phase 15 can be suppressed. In other words, even if the first phase 13 is to occlude lithium to expand the volume, the second phase 15 is difficult to expand, and the second phase 15 exerts an effect such as a wedge or a pin, and the expansion of the entire nano-sized particles 11 or 17 is suppressed. Therefore, the nanosized particle 11 or 17 having the second phase 15 is less likely to swell when the lithium is occluded than the particles having no second phase 15, and the restoring force acts upon returning lithium to easily return to the original shape. Therefore, according to the present invention, even if the lithium-sized particles 11 or 17 absorb lithium, the distortion accompanying the volume expansion can be alleviated, and the discharge capacity at the time of suppressing the cycle characteristics can be lowered.

Further, according to the second embodiment, since the nanosized particle 11 or 17 is not easily expanded, it is difficult to react with oxygen in the atmosphere even if the nanosized particle is taken out to the atmosphere. On the other hand, if a nano-sized particle having only one of the phases is placed in the atmosphere without protecting the surface, it will react with oxygen from the surface, and the entire surface of the nano-sized particles will be oxidized by oxidation from the surface to the inside of the particle. . However, when the nanosized particle 11 or 17 of the present invention is placed in the atmosphere, although the outermost surface of the particle reacts with oxygen, the entire size of the nanoparticle is not easily expanded, so that oxygen does not easily intrude into the interior, and it is difficult to oxidize and To the center of the nanometer-sized particles. Therefore, although the usual metal nanoparticles have a large specific surface area and are also oxidized to generate heat or volume expansion, the nanosized particle 11 or 17 of the present invention does not necessarily require special surface plating with an organic substance or a metal oxide. It can be used as it is in the atmosphere. Such a feature is of great value in industrial use.

Further, according to the second embodiment, the second phase 15 has high conductivity due to the inclusion of the element M, and even the first phase 13 containing the element X having low conductivity is present as the main phase, and the nano-sized particles 11 or 17 are all present. The electrical conductivity also rises dramatically. In other words, the nano-sized particle 11 or 17 is equivalent to a structure having a nano-level collector point in each nano-sized particle, and is a negative electrode material having conductivity even if the conductive additive is small, and can form a high-capacity material. Further, the electrode can obtain a negative electrode active material having high efficiency and excellent characteristics. In particular, by using a metal element such as Fe or Cu having high conductivity in the second phase 15, a negative electrode active material having excellent conductivity can be obtained as compared with the case of the individual ruthenium nanoparticles.

Further, the first phase 13 includes the nano-sized particles 11 of the second phase 15 and the first phase 13 including the second phase 15 and the other nano-sized particles 19 of the second phase 19, which are the first phase. More of the portion of 13 is in contact with the phase which does not absorb lithium, and the expansion of the first phase 13 can be more effectively suppressed. As a result, the nanosized particle 17 can exhibit an effect of suppressing volume expansion with a small amount of the element M, and can effectively increase the amount of the element X such as Si which can absorb lithium, thereby improving the high capacity and cycle characteristics.

The nanosized particle 17 having both the second phase 15 and the other second phase 19 exposed to the outer surface has the same effect as described above, and the nanometer-level collector point is increased to make the current collecting performance effective. Upgrade. When two or more elements of the element M and the group of the elements M' are added, two or more kinds of compounds are produced, and since these compounds are easily separated from each other, it is easy to separate different compounds, and it is preferable to make the collection points easy to add. .

(2-5. Configuration of Negative Electrode Active Material C of Third Embodiment)

Further, the nanosized particle 21 of the third embodiment of the negative electrode 5 of the present invention will be described. In the following embodiments, the same components as those in the second embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

Fig. 6 is a schematic cross-sectional view showing the nanosized particle 21 constituting the negative electrode active material of the negative electrode 5 of the present invention. As shown in FIG. 6(a), the nanosized particle 21 further has a third phase 23 in addition to the first phase 13 and the second phase 15 which are the same as described above. The third phase 23 includes an element X' which is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, and is different from the element X. The element. These elements X' are elements which are easily occluded with lithium. The third phase 23 may be a monomer of the element X' or a solid solution containing the element X' as a main component. The element X' and the element forming the solid solution may be an element selected from the group of the selectable elements X', and may also be an element not mentioned in the aforementioned group. The third phase 23 can absorb lithium.

All of the first phase 13, the second phase 15, and the third phase 23 are all exposed to the outer surface, and the outer surfaces of the first phase 13, the second phase 15, and the third phase 23 may be substantially spherical. The second phase 15 is joined to the first phase 13 and the third phase 23 through the interface and at least one of the first phase 13 and the second phase 15 are joined to each other. For example, the second phase 15 is present at one end of the first phase 13 and the third phase 23 is formed at the other end, and the nano-sized particles 21 may have a shape in which the surface of the large sphere and the two small spheres are joined. The interface between the third phase 23 and the first phase 13 displays a plane or a curved surface. On the other hand, as shown in FIG. 7(a), the second phase 15 and the third phase 23 can also be bonded through the interface.

In the case of such a nano-sized particle 21, the lithium storage property and the conductivity of the negative electrode active material are considered, for example, the first phase 13 is Si, the second phase 15 is a compound of Si and Fe, and the third phase 23 is exemplified. For Sn and so on.

Further, as in the nanosized particle 21 shown in Fig. 6(b), the monomer of the element M or the second phase 15 of the compound, and the monomer of the element X' or the third phase 23 of the solid solution may be dispersed. In the first phase 13. Further, a phase (not shown) of the compound of the element X' and the element M may be dispersed. Although the phases 15 and 23 are covered by the first phase 13, as shown in Fig. 6(c), a part of the phases 15, 23 may be exposed to the surface. In other words, it is not necessary to cover all of the phases 15 and 23 dispersed in the first phase 13 by the first phase 13, or the first phase 13 may cover only a part of the periphery. Further, in the first phase 13, a plurality of phases may be dispersed, for example, any of the phases of the second phase 15, the third phase 23, the element X' and the compound of the element M may be dispersed.

Further, the shape of the surface other than the interface of the third phase 23 is the same as the third phase 23 shown in FIG. 6(a), and the surface may be a substantially smooth spherical surface, as shown in FIG. 7(b). The third phase 23' is generally a polyhedral shape. The polyhedral shape is produced by joining the nano-sized particles 11, 17, or 21 through the third phase 23 and then peeling off.

Further, the first phase 13 and the third phase 23 are capable of suppressing the position of reaction with lithium by containing oxygen. Although the inclusion of oxygen reduces the capacity, the volume expansion accompanying the occlusion of lithium can be suppressed. When the amount z of oxygen added is, for example, XO _z or X'O _z , it is preferably in the range of 0 < z < 1. When z is 1 or more, the Li occlusion position of the element X and the element X' is suppressed, and the capacity is largely lowered.

In the case where the nanosized particle contains the element X, the element X', the element M, and the element M', the atomic ratio of the element M and the element M' which occupy the total of these is preferably 0.01 to the same reason as described above. 25% or so. When the atomic ratio is 0.01 to 25%, when the nanosized particle 21 is used as a negative electrode active material, both cycle characteristics and high capacity can be achieved.

Further, regarding the configuration of the nanosized particle 21 of the present invention, other various aspects can be considered. For example, a plurality of third phases 23 may be provided on the surface of the first phase 13. Further, for example, the nanosized particle 21 may further contain two or more elements X'. For example, the second element X' is one element selected from the group of the elements X', and the first element X' is an element of a different type. For example, element X may be used, and element X' may be tin or aluminum. The element X' may form another third phase by a monomer or a solid solution, or may form a compound with the element M and the element M'. The other third phase system is the same as the third phase 23, and the outer surface is spherical and can be exposed to the outer surface of the nano-sized particles 21. Further, the phase of the compound of the element X' and the element M may be dispersed in the first phase 13 or the third phase 23. Further, the nanosized particle 21 may contain the element M' in addition to the element M.

As such, the nano-sized particles 21 may include elements of the group of elements X, X', elements of the group of elements M, and various combinations of elements of the group of elements M', compounds of various compositions, and solid solution. Body phase. Such a phase may be exposed to the surface of the nano-sized particles 21 or may be dispersed in the first phase 13 or any other phase.

Further, the outermost surface of the nanosized particle 21 may be bonded to oxygen. When the nanosized particle 21 is taken out in the air, oxygen in the air reacts with the element on the surface of the nanosized particle 21. In other words, the outermost surface of the nanosized particle 21 may have an amorphous layer having a thickness of about 0.5 to 15 nm, and may have an oxide film layer particularly when the first phase is mainly a crystalline ruthenium.

(2-6. Effect of negative electrode active material C)

According to the third embodiment, the same effects as those obtained in the second embodiment can be obtained. However, according to the third embodiment, the first phase 13 absorbs lithium as a volume, and the third phase 23 expands as soon as lithium is stored. However, in the first phase 13 and the third phase 23, the electrochemical potential of occluding lithium is different, and the phase occludes lithium in preference to one phase. When the phase volume of one side expands, the volume expansion of the other phase is relatively Less, the other side of the phase will become less of a volume expansion on this side. Therefore, the nanosized particle 21 having the first phase 13 and the third phase 23 is less likely to swell when absorbing lithium than the particles in the case where the third phase 23 is not present. Therefore, according to the third embodiment, the nanosized particle 21 can suppress volume expansion even when lithium is stored, and can suppress the decrease in discharge capacity at the time of cycle characteristics.

(2-7. Other aspects of the negative electrode active material)

Moreover, as the negative electrode active material of the present invention, the first particle 9 of the negative electrode active material A may be a nano-sized particle of the negative electrode active material B and C. By doing so, the negative electrode active material A can further obtain the same effects as the negative electrode active materials B and C.

Further, as the negative electrode active material of the present invention, for example, copper, tin, zinc, silver, nickel or carbon is coated on the first particles 9 of the negative electrode active materials A to C, and the nanosized particles 11 and 17, At least a portion of the surface of 21. The thickness of the coating is exemplified as a range of 0.01 to 0.5 μm. Such a configuration can also be understood as, for example, in the nano-sized particles 17 shown in FIG. 5, Cu is selected as the element M', and the other second phase 19 of the monomer of the element M' is not the surface of the first phase 13 The bonding is performed to cover the first phase 13 and the second phase 15 (not shown).

By coating the surface of the negative electrode active material with a material having good conductivity, the conductivity of the entire negative electrode can be improved and the cycle characteristics can be improved without using a conductive auxiliary material or the like. Further, since the surface of the negative electrode active material is coated, oxidation of ruthenium or the like can be suppressed. By covering the surface, the volume change caused by charge and discharge is also improved.

(2-8. Manufacturing method of nanometer size particles)

Here, a method of producing nano-sized particles will be described.

Nanosized particles can be synthesized by gas phase synthesis. Specifically, nanosized particles can be produced by slurrying and heating the raw material powder to a temperature equivalent to 10,000 K, followed by cooling.

A specific example of a manufacturing apparatus used for producing nano-sized particles will be described below based on Fig. 8 . In the nano-sized particle production apparatus 37 shown in Fig. 8, a high-frequency coil 46 for generating plasma is wound around the upper outer wall of the reaction chamber 39. An alternating current voltage of several MHz is applied to the high frequency coil 46 with the high frequency power source 47. The preferred frequency is 4 MHz. Further, the outer wall of the upper portion of the wound high-frequency coil 46 is a cylindrical double-layered tube made of quartz glass or the like, and cooling water is passed through the gap to prevent the quartz glass from being melted by the plasma.

Further, a raw material powder supply port 41 and a shielding gas supply port 43 are provided in the upper portion of the reaction chamber 39. The raw material powder 42 supplied from the raw material powder feeder is supplied to the plasma 49 through the raw material powder supply port 41 together with the carrier gas 45 (inert gas such as helium or argon). Further, the shielding gas 44 is supplied to the reaction chamber 39 through the shielding gas supply port 43. Further, the raw material powder supply port 41 is not necessarily provided on the upper portion of the plasma 49 as shown in Fig. 8, and a nozzle may be provided in the lateral direction of the plasma 49. Further, the raw material powder supply port 41 may be water-cooled by cooling water. Further, the state of the raw material of the nano-sized particles supplied to the plasma is not limited to the powder, and a slurry of the raw material powder or a gaseous raw material may be supplied.

The reaction chamber 39 serves to maintain the pressure of the plasma reaction portion and suppress the dispersion of the produced fine powder. The reaction chamber 39 is also water-cooled in order to prevent damage due to plasma. Further, the suction pipe is connected to the side portion of the reaction chamber 39, and a filter 51 for collecting the synthesized fine powder is provided in the middle of the suction pipe. The suction pipe connecting the reaction chamber 39 and the filter 51 is also water-cooled with cooling water. The pressure in the reaction chamber 39 is adjusted by the suction force of the vacuum pump VP (not shown) provided on the downstream side of the filter 51.

The method for producing a nano-sized particle is a method in which a plasma is passed through a gas or a liquid to form a solid, and a nano-sized particle is precipitated from the bottom to the bottom, and the first phase 13 and the second phase 15 are formed in a droplet shape. Spherical. On the other hand, in the method of reducing the large particles from top to bottom as in the case of the crushing method or the mechanochemical method, the shape of the particles is not smooth, and the shape of the spherical shape of the nano-sized particles 11 is greatly different.

Further, when a mixed powder of the powder of the element X and the element M is used as the raw material powder, the nanosized particle 11 of the second embodiment can be obtained. On the other hand, when the mixed powder of the powder of the element X, the element M, and the element M' is used as the raw material powder, the nanosized particle 17 of the second embodiment can be obtained. Further, when a mixed powder of the element X, the element M (and the element M'), and the powder of the element X' is used as the raw material powder, the nanosized particle 21 of the second embodiment can be obtained.

The first particle and the second particle of the first embodiment can be produced by using the above-described nano-sized particle production apparatus and method, and can be produced by various methods known in the art.

Further, the method of coating the surface of the particles is not particularly limited, and various methods known in the art can be employed. For the coating of the metal, electroless plating or displacement plating may be used, and plating may be performed in the case where the surface of the particles such as ruthenium is small in oxidation and conductive. For the carbon coating, a method of heat-treating in an inert or reducing atmosphere after mixing an organic-based carbon source such as inorganic black or polyvinyl alcohol such as carbon black can be used. Further, a thermal decomposition CVD method in which carbon is applied to the surface of the particles by thermal decomposition of the hydrocarbon-based gas to 600 ° C or higher is used.

(2-9. Manufacturing method of negative electrode)

Next, a method of producing a negative electrode for a nonaqueous electrolyte secondary battery will be described. The negative electrode of the present invention can be formed by applying a coating liquid containing at least a negative electrode active material, a conductive material, and a bonding material to a current collector, followed by drying. The coating liquid can be prepared by, for example, putting the slurry raw material 57 into the mixer 53 and kneading it to form a slurry (coating liquid) 55, as shown in Fig. 9 . The slurry raw material 57 is a nano-sized particle, a conductive auxiliary agent, an adhesive, a tackifier, a solvent, and the like.

The solid content in the slurry 55 can be adjusted to, for example, 25 to 90% by weight of the nanosized particles, 5 to 70% by weight of the conductive auxiliary agent, 1 to 30% by weight of the adhesive, and 0 to 25% by weight of the tackifier.

The mixer 53 can be a general kneader for the preparation of a slurry, or a device capable of adjusting to a so-called slurry using a kneader, a mixer, a disperser, a mixer or the like. In addition, one or a mixture of two or more kinds of polysaccharides such as carboxymethyl cellulose and methyl cellulose can be suitably used as the tackifier. Also, water can be used as a solvent. Further, when preparing an organic slurry, it can be used as a solvent for N-methyl-2-pyrrolidone.

The conductive auxiliary agent is a powder composed of at least one conductive material selected from the group consisting of carbon, copper, tin, zinc, nickel, silver, and the like. It may be a powder of a monomer of carbon, copper, tin, zinc, nickel or silver, or a powder of each alloy. For example, general carbon black such as furnace black or acetylene black can be used. Further, the carbon nanohorn can be added as a conductive additive. In particular, in the case where the element X of the nano-sized particles is low in conductivity, the ruthenium is exposed to the surface of the nano-sized particles, and since the conductivity is lowered, it is preferable to add the nano-carbon corner as a conductive auxiliary agent. Here, the carbon nanosphere (CNH) is a structure in which a graphite film is rounded into a conical shape, and the actual form is a large number of CNH vertices facing outward, and exists in a form of a radial sea urchin. The outer diameter of the urchin-like aggregate of CNH is about 50 nm to 250 nm. Particularly preferred is CNH having an average particle diameter of about 80 nm. These materials may be used alone or in combination of two or more.

The average particle size of the conductive additive also specifies the average particle size of the primary particles. The same is true in the case of a highly developed structural shape such as acetylene black. Here, the average particle diameter is defined by the primary particle diameter, and the average particle diameter can be obtained by image analysis of the SEM photograph.

Further, both a particulate conductive auxiliary agent and a conductive conductive auxiliary agent may be used. The wire-like conductive auxiliary agent is a conductive material lead wire, and can be used as a conductive material exemplified for the particulate conductive auxiliary agent. As the wire-like conductive auxiliary agent, a linear body having an outer diameter of 300 nm or less, such as a carbon fiber, a carbon nanotube, a copper nanowire, or a nickel nanowire, can be used. By using a conductive conductive auxiliary agent, it is easy to maintain electrical connection with a negative electrode active material, a current collector, etc., and while improving current collecting performance, a fibrous substance is added to a porous film-shaped negative electrode, and cracks are less likely to occur in the negative electrode. For example, it is considered to use copper powder as a particulate conductive auxiliary agent, and a wire-shaped conductive auxiliary agent is used as a vapor grown carbon fiber (VGCF: Vapor Grown Carbon Fiber). Further, in addition to the particulate conductive auxiliary agent, only a wire-shaped conductive auxiliary agent may be used.

The length of the wire-shaped conductive auxiliary agent is preferably from 0.1 μm to 2 mm. The outer diameter of the conductive auxiliary agent is preferably from 4 nm to 1000 nm, more preferably from 25 nm to 200 nm. When the length of the conductive auxiliary agent is 0.1 μm or more, the productivity of the conductive auxiliary agent is increased to a sufficient length, and when the length is 2 mm or less, the application of the slurry is facilitated. Further, in the case where the outer diameter of the conductive auxiliary agent is thicker than 4 nm, it is easy to synthesize, and when the outer diameter is smaller than 1000 nm, the kneading of the slurry is easy. The method of measuring the outer diameter and length of the conductive material is carried out by image analysis based on SEM.

Further, as an adhesive for the resin, a fluororesin such as polyvinylidene fluoride (PVdF) or a synthetic rubber such as styrene butadiene rubber (SBR), an acrylate resin, or a cellulose such as carboxymethyl cellulose can be used. Organic materials such as polyimine and polyamidoximine. Any one of these materials may be used, or two or more types may be used in combination.

As the solvent, water or N-methyl-2-pyrrolidone (NMP) or the like can be used.

Next, as shown in FIG. 10, the slurry 55 is applied to one surface of the current collector 61 using, for example, an applicator 59. As the applicator 59, a general coating device capable of applying the slurry 55 to the current collector 61, for example, a roll coater, a blade-based applicator, a notch applicator, and a slit coater can be used.

The current collector 61 is a foil formed of at least one metal selected from the group consisting of copper, nickel, and stainless steel. Each metal can be used alone or as a separate alloy. The thickness is preferably from 4 μm to 35 μm, and more preferably from 8 μm to 18 μm.

After that, it is dried at about 50 to 150 ° C, and a negative electrode for a nonaqueous electrolyte secondary battery can be obtained by rolling under pressure to adjust the thickness. As the adhesive material, in the case of using polyimide or polyamidimide, it is preferred to further heat-treat in the range of 250 ° C to 450 ° C.

(3. Positive)

As the positive electrode 3, various positive electrodes capable of occluding and releasing lithium ions can be used. The positive electrode for a lithium ion battery can be produced by mixing a positive electrode active material, a conductive auxiliary agent, an adhesive, a solvent, and the like to prepare a composition of a positive electrode active material, which is directly coated/dried on a metal current collector such as an aluminum foil.

The positive electrode active material can be used as long as it is generally used, and examples thereof include LiCoO ₂ , LiMn ₂ O ₄ , LiMnO ₂ , LiNiO ₂ , LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , A compound such as LiFePO ₄ .

As the conductive auxiliary agent, for example, carbon black can be used, and as an adhesive, for example, polyvinylidene fluoride (PVdF), a water-soluble acrylate-based adhesive can be used, and as a solvent, N-methyl-2-pyrrolidone can be used. (NMP), water, etc. In this case, the contents of the positive electrode active material, the conductive auxiliary agent, the adhesive, and the solvent are generally used in a grade such as a nonaqueous electrolyte secondary battery.

(4. spacer material)

As the separator, any one of the nonaqueous electrolyte secondary batteries can be used as long as it has a function of conducting electrons of the insulated positive electrode and the negative electrode. For example, a microporous polyolefin film can be used.

(5. electrolyte / electrolyte)

As the electrolyte solution and electrolyte used in a lithium ion secondary battery or a Li polymer battery, a nonaqueous organic electrolyte solution having lithium ion conductivity can be used.

Specific examples of the solvent of the organic electrolytic solution include carbonates such as ethyl acetate, propyl carbonate, butyl carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate; diethyl ether and dibutyl Ethers such as ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether; benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyl An aprotic solvent such as lactone, dioxane, 4-methyldioxane, N,N-dimethylformamide, dimethylacetamide, dimethylchlorobenzene or nitrobenzene, or A mixed solvent obtained by mixing two or more kinds of solvents.

The electrolyte of the organic electrolyte may be composed of LiPF ₆ , LiClO ₄ , LiBF ₄ , LiAlO ₄ , LiAlCl ₄ , LiSbF ₆ , LiSCN, LiCl, LiCF ₃ SO ₃ , LiCF ₃ CO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ or an electrolyte composed of a lithium salt or a mixture of two or more kinds.

Next, the present invention is characterized in that the electrolyte contains an organic substance having an unsaturated bond in the molecule and capable of being reductively polymerized. By adding such an organic substance to the electrolyte, an effective solid electrolyte interface coating film can be formed on the surface of the negative electrode active material, and decomposition of the electrolyte material can be suppressed. A substance having an unsaturated bond in a molecule and capable of reducing polymerization upon charging, for example, in addition to a carbonate such as fluoroethylene carbonate, vinylene carbonate (VC) or ethylene carbonate, and a derivative thereof, Unsaturated carbonates, phosphates, borates, alcohols, and the like. Among them, vinylene carbonate (VC) is used as a preferred example.

Such an organic substance is preferably added in an amount of from 0.1% by weight to 10% by weight based on the weight of the electrolyte in order to obtain a stable solid electrolyte interface coating film. More preferably, it is added in an amount of about 1% by weight to 5% by weight. When the amount of addition is in the range of 0.1% by weight to 10% by weight, it can be reduced at the time of charging, and a stable coating film can be formed on the surface of the negative electrode active material layer, thereby preventing decomposition of the electrolyte material. When the amount of addition is less than 0.1% by weight, it is difficult to form a sufficiently stable coating film on the surface of the negative electrode active material, and in the case where the amount added exceeds 10% by weight, the solid electrolyte formed by the amount of reduction is increased. The interface film becomes thicker, causing the impedance of the battery to rise and is less favorable.

(6. Assembly of nonaqueous electrolyte secondary battery)

In the nonaqueous electrolyte secondary battery of the present invention, the separator is disposed between the positive electrode and the negative electrode as described above to form a battery structure. After winding or folding such a battery structure, a cylindrical or square battery case is placed, and an electrolyte is injected to complete a lithium ion secondary battery.

Specifically, as shown in FIG. 1, the nonaqueous electrolyte secondary battery 1 of the present invention is configured such that the positive electrode 3 and the negative electrode 5 are laminated in the order of the separator-negative electrode-separator-positive electrode through the separator 7, and the positive electrode 3 is wound back. The inner electrode plate group is inserted into the battery can body 25. Then, the positive electrode 3 is connected to the positive electrode terminal 29 through the positive electrode lead 27, and the negative electrode 5 is connected to the battery can body 25 through the negative electrode lead 31. The chemical energy generated inside the nonaqueous electrolyte secondary battery 1 is taken out as electric energy and taken out to the outside. Next, the non-aqueous electrolyte solution 8 is filled in the battery can body 25 so as to cover the electrode plate group, and then the sealing plate composed of the circular cover plate and the upper positive electrode terminal 29 is provided with a safety valve mechanism inside. The body 33 is attached to the upper end (opening) of the battery can 25 through an annular insulating spacer, whereby the nonaqueous electrolyte secondary battery 1 of the present invention can be produced.

(7. Effect of the nonaqueous electrolyte secondary battery of the present invention)

Nonaqueous electrolyte secondary battery of the present invention By using a nano-sized particle containing Si having a capacity higher than that of carbon per unit volume as a negative electrode active material, the capacity is larger than that of a conventional lithium ion secondary battery, and it is excellent in that the nano-sized particles are not easily micronized. Cycle characteristics.

Further, in the case of using such a nano-sized negative electrode active material to form a negative electrode by a coating method, it is also effective to form a stable surface on the surface of the negative electrode active material layer by including an organic substance capable of reductive polymerization having an unsaturated bond in the electrolyte. The film stabilizes the negative electrode active material and inhibits decomposition of the electrolyte to improve cycle characteristics.

Example

Hereinafter, the present invention will be specifically described by way of Examples and Comparative Examples.

[Example 1]

(nano size particles)

Using the apparatus of FIG. 8, the tantalum powder and the iron powder are mixed in a molar ratio of Si:Fe=23:2, and the dried mixed powder is used as a raw material powder, and is continuously supplied to the reaction chamber by a carrier gas. In the plasma of Ar gas, the nanoparticles of niobium and iron are produced.

In detail, it is manufactured by the following method. After the reaction chamber was evacuated by a vacuum pump, Ar gas was introduced to atmospheric pressure. This exhaust gas and the introduction of Ar gas were introduced three times, and the residual exhaust gas in the reaction vessel was left. Thereafter, Ar gas as a plasma gas was introduced into the reaction vessel at a flow rate of 13 L/min, an alternating voltage was applied to the high frequency coil, and high frequency plasma was generated by a high frequency electromagnetic field (frequency: 4 MHz). The board power at this time is 20 kW. The carrier gas system for supplying the raw material powder uses an Ar gas having a flow rate of 1.0 L/min. The obtained fine powder was recovered by a filter.

(Evaluation of the composition of nanometer-sized particles)

Regarding the crystallinity of the nano-sized particles, XRD analysis was carried out using RINT-Ultima III manufactured by Rigaku Corporation. An XRD diffraction pattern of the nano-sized particles of Example 1 is shown in FIG. The nanosized particle obtained in Example 1 was composed of two components of Si and FeSi ₂ . Further, it is understood that Fe is present in the form of telluride FeSi ₂ , and the Fe element of the elemental monomer (valence number 0) hardly exists.

The particle shape of the nano-sized particles was observed using a scanning transmission electron microscope (manufactured by JEOL Ltd., JEM 3100FEF). Fig. 12 (a) is a BF-STEM (Bright-Field Scanning Transmission Electron Microscopy) diagram of the nano-sized particles of Example 1. It was observed that hemispherical particles were bonded to the substantially spherical particles having a particle diameter of about 80 to 100 nm through the interface. In the same particle, the darker color was composed of iron-containing iron telluride, and the lighter color was caused by 矽. Composition. Further, it was found that an oxide film of ruthenium having an amorphous thickness of 2 to 4 nm was formed on the surface of the nanosized particles. Fig. 12 (b) is a STEM photograph obtained by HAADF-STEM (High Angle Annular Dark Field Scanning Transmission Electron Microscopy). In HAADF-STEM, in the same particle, the lighter color is composed of iron sulphate and the darker color is composed of strontium.

The observation of the particle shape of the nano-sized particles and the composition analysis were carried out by scanning a transmission electron microscope (JEM 3100FEF, manufactured by JEOL Ltd.), and the particle shape of HAADF-STEM was observed, and EDS (Energy Dispersive Spectroscopy) was used. Analysis) analysis. Fig. 13(a) is a HAADF-STEM image of nano-sized particles, Fig. 13(b) is an EDS spectrum of germanium atoms at the same observation point, and Fig. 13(c) is an EDS spectrum of iron atoms at the same observation point.

According to Fig. 13 (a), nano-sized particles having a particle diameter of about 50 to 150 nm were observed, and each of the nano-sized particle systems was substantially spherical. As is clear from Fig. 13(b), the ruthenium atom is present in the entire nano-sized particle, and as is clear from Fig. 13(c), a large amount of iron atoms are detected in the bright portion observed in Fig. 13(a). As can be seen from the above, the nanosized particle structure has a structure in which the second phase formed of a compound of cerium and iron is bonded to the first phase formed by cerium.

The particle shape observation and composition analysis of the other nano-sized particles of Example 1 were carried out in the same manner as in Figs. 14 (a) to (c). Fig. 14 is also the same as Fig. 13 and shows a structure in which a second phase formed of a compound of bismuth and iron is bonded to a first phase formed of ruthenium.

Next, the formation process of the nano-sized particles obtained was studied. Figure 15 is a binary system state diagram of Si and Fe. The tantalum powder and the iron powder were mixed in a molar ratio of Si:Fe=23:2 so that the raw material powder had a molar Si/(Fe+Si)=0.92. The thick line in Fig. 15 shows the line of Moer Si / (Fe + Si) = 0.92. The plasma generated by the high-frequency coil is equivalent to 10,000 K, far beyond the temperature range of the state diagram, and a plasma in which iron atoms and helium atoms are uniformly mixed can be obtained. When the plasma is cooled, it grows into spherical droplets during the process of changing from plasma to gas and from gas to liquid. When cooled to about 1470K, both Fe ₃ Si ₇ and Si are precipitated. Thereafter, when cooled to about 1220 K, the Fe ₃ Si ₇ phase changes to FeSi ₂ and Si. Therefore, if the plasma of ruthenium and iron is cooled, nano-sized particles in which FeSi ₂ and Si are interfacially bonded to each other are formed. Since Si has a low affinity with Fe, Si and Fe have a shape in which two particles are joined to each other so as to reduce the contact area with each other.

The obtained nano-sized particles had an average particle diameter of 100 nm.

(Evaluation of powder conductivity)

In order to evaluate the electron conductivity of the powder state, the powder electrical conductivity was evaluated using the powder resistance measurement system MCP-PD51 manufactured by Mitsubishi Chemical Corporation. The conductivity is determined by the resistance of the sample powder as it is compressed by any pressure. The information in Table 1 below is the value measured by compressing the sample powder at 63.7 MPa.

(Evaluation of cycle characteristics of nonaqueous electrolyte secondary battery)

(i) Modulation of negative electrode slurry

The nano-sized particles of Si and Fe obtained as described above are used as a negative electrode active material, and acetylene black (manufactured by Electric Chemical Industry Co., Ltd., powdery product) which is a conductive material is put into a mixer, and further mixed as Adhesive of styrene-butadiene rubber (SBR) 40wt% emulsion (made by Japan ZEON Co., Ltd., BM-400B), sodium carboxymethyl cellulose as a tackifier for adjusting the viscosity of the slurry (Daicel Chemical industry (stock), #2200) 1wt% solution to make a slurry. The slurry was prepared so that the negative electrode active material was 64% by weight, the conductive material was 16% by weight, the subsequent material (in terms of solid content) was 5% by weight, and the tackifier (in terms of solid content) was 15% by weight.

(ii) Production of negative electrode

The prepared slurry was applied to an electrolytic copper foil for a current collector (manufactured by Furukawa Electric Co., Ltd., NC-WS) having a thickness of 10 μm using a doctor blade of an automatic coating device, and dried at 70 ° C for 10 minutes. To manufacture the negative electrode A.

(iii) Evaluation

The test electrode used the negative electrode A, the counter electrode and the reference electrode were made of lithium, the separator was made of a polyolefin microporous film, and the electrolyte was used for an ethylene carbonate (EC) containing 1.3 mol/L of LiPF _{6 or} a methyl carbonate. An electrolyte solution containing 1% by weight of vinylene carbonate (VC) was added to a mixed solution of an ester (EMC) and dimethyl carbonate (DMC) to form a battery for evaluation, and the charge and discharge characteristics were examined.

The evaluation of the charge and discharge characteristics was carried out by measuring the initial discharge capacity and the discharge capacity after charging/discharging for 50 cycles, and calculating the ratio of the discharge capacity after charge/discharge with respect to the initial discharge capacity and the cycle of 50 cycles. For the capacity retention rate. The discharge capacity is calculated by removing the ruthenium and tin which do not occlude/release lithium, such as a telluride, and based on the weight of the active material Si (in the case where Sn is also included, Si and Sn) in which lithium is efficiently stored/released. First, at a current of 25 ° C, a constant current is charged to a voltage of 0.02 V at a current of 0.1 C, and constant voltage charging is performed until the current value is lowered to 0.05 C. Next, a constant current discharge was performed to a voltage of 1.5 V at a current of 0.1 C, and an initial discharge capacity of 0.1 C was measured. The 1C system can fully charge the current value in 1 hour. Next, the above charge and discharge cycle was repeated 50 times.

[Embodiment 2]

Using the apparatus of FIG. 8, the tantalum powder and the iron powder were mixed in a molar ratio of Si:Fe=38:1, and the dried mixed powder was used as a raw material powder, and the average particle diameter was produced in the same manner as in Example 1. It is a nanometer size particle of 100 nm. Then, using this nano-sized particle as a negative electrode active material, the negative electrode B was produced in the same manner as in Example 1, and a battery for evaluation was constructed, and the charge and discharge characteristics were examined.

Figure 16 shows an XRD diffraction pattern of the nano-sized particles of Example 2. It is understood that Example 2 is composed of two components of Si and FeSi ₂ . Further, it is understood that Fe is all present in the telluride FeSi ₂ , and Fe of the elemental monomer hardly exists. Further, when compared with FIG. 9, the ratio of Fe was smaller than that of the nanosized particles of Example 1, and the peak derived from FeSi ₂ was only a trace amount and could not be confirmed.

The results of STEM observation are shown in Fig. 17. According to Fig. 17 (a), a large number of substantially spherical particles having a diameter of about 50 to 150 nm were observed. In the non-overlapping particles, the dark-colored portion is considered to be iron-telluride, and the light-colored portion is considered to be sputum. Further, it was observed that the atomic system of the ruthenium portion was regularly arranged, and it was found that the ruthenium was crystalline in the first phase. Further, as is clear from Fig. 17(b), the surface of the nano-sized particles is partially covered with an amorphous layer having a thickness of about 1 nm, and the iron-deuterated portion is covered with an amorphous layer having a thickness of about 2 nm. Further, by comparing STEM photograph of FIG. 12 and FIG. 17, confirmed that the relative size of Si and FeSi _2, FeSi understood Example 2 nm of particle size than that of Example ₂ FeSi-based particle size of ₁₂ nm Small .

The particle shape observed by HAADF-STEM and the results of EDS analysis are shown in Figs. 18 and 19 . According to Fig. 18 (a), it was observed that the nano-sized particle systems having a particle diameter of about 150 to 250 nm were substantially spherical. As is clear from Fig. 18(b), the ruthenium atom is present in the entire size of the nano-sized particles, and as is clear from Fig. 18(c), a large amount of iron atoms are detected in the bright portion observed in Fig. 18(a). As is clear from Fig. 18(d), it is considered that the oxygen atom system derived from oxidation is distributed substantially over the entire nano-sized particles.

Similarly, according to Fig. 19 (a), substantially spherical nano-sized particles having a particle diameter of about 250 nm were observed, and as shown in Fig. 19 (b), germanium atoms existed in the entire nano-sized particles, as shown in Fig. 19 (c). It can be seen that a large amount of iron atoms were detected in the bright portion observed in Fig. 19 (a). As is clear from Fig. 19(d), it is considered that the oxygen atomic system derived from oxidation is distributed substantially over the entire nano-sized particles. As can be seen from the above, the nanosized particle structure has a structure in which the second phase formed of a compound of cerium and iron is bonded to the first phase formed by cerium.

[Example 3]

Using the apparatus of FIG. 8, the tantalum powder and the iron powder were mixed in a molar ratio of Si:Ni=12:1, and the dried mixed powder was used as a raw material powder, and the average particle diameter was produced in the same manner as in Example 1. It is a nanometer size particle of 100 nm. Then, using this nano-sized particle as a negative electrode active material, the negative electrode C was produced in the same manner as in Example 1, and a battery for evaluation was constructed, and the charge and discharge characteristics were examined.

An XRD diffraction pattern of the nano-sized particles of Example 3 is shown in FIG. It is understood that Example 3 is composed of two components of Si and NiSi ₂ . Further, it was found that all of the Ni-based telluride NiSi _{2 was} present, and Ni of the elemental monomer (valence number 0) hardly existed. It can be seen that the diffraction angles 2θ of Si and NiSi ₂ are identical, and the surface intervals are almost the same.

Fig. 21(a) is a BF-STEM diagram, and Fig. 21(b) is a HAADF-STEM diagram of the same field of view. According to Fig. 21, nano-sized particles having a particle diameter of about 75 to 150 nm were observed, and each of the nano-sized particles had a shape in which substantially other hemispherical particles were bonded to the respective substantially spherical particles through the interface.

Fig. 22 is a high-resolution TEM image of the nano-sized particles of Example 3. In (a) to (c) of Fig. 22, the lattice diagram is observed, and the lattice fringes of the 矽 phase and the bismuth phase are substantially identical, and it is understood that the bismuth compound has a polyhedral shape. Moreover, the boundary between the 矽 phase and the 矽 phase is linear, curved, or stepped. Further, it is understood that the surface of the nanosized particle is covered with an amorphous layer having a thickness of about 2 nm.

The HAADF-STEM image of the nano-sized particles of Example 3 and the results of EDS analysis are shown in FIG. According to Fig. 23 (a), nanosized particles having a particle diameter of about 75 to 150 nm were observed. As is clear from Fig. 23(b), the ruthenium atom is present in the entire size of the nano-sized particles, and as is clear from Fig. 23(c), a large amount of nickel atoms are detected at the bright portion observed in Fig. 23(a). As can be seen from the above, the nanosized particle structure has a structure in which the second phase formed of a compound of ruthenium and nickel is bonded to the first phase formed by ruthenium. Further, as is clear from Fig. 23(d), it is considered that the oxygen atom system derived from oxidation is distributed substantially in the entire nano-sized particles.

[Example 4]

Using the apparatus of Fig. 8, the tantalum powder and the iron powder were mixed in such a manner that the molar ratio Si:Fe:Sn=21:1:1, and the dried mixed powder was used as the raw material powder, and the same method as in Example 1 was used. A nano-sized particle having an average particle diameter of 100 nm was produced. Then, using this nano-sized particle as a negative electrode active material, the negative electrode D was produced in the same manner as in Example 1, and a battery for evaluation was constructed, and the charge and discharge characteristics were examined.

Figure 24 is an X-ray diffraction (XRD) pattern of the nano-sized particles of Example 4. It is understood that the nanosized particles of Example 4 have Si, Sn, and FeSi ₂ .

25(a) to (b) show STEM photographs of the nanosized particles of Example 4. It was observed that the outer surface having a particle diameter of about 50 to 150 nm is a substantially spherical nano-sized particle. In Fig. 25(a), the portion having a rich color is considered to be Sn, and the portion having a light color is considered to be Si.

26(a) to (b) show STEM photographs of the nanosized particles of Example 4. It was observed that the outer surface having a particle diameter of about 50 to 150 nm is a substantially spherical nano-sized particle. The bright areas are considered to be mainly composed of Sn, while the dark areas are considered to be mainly composed of Si.

According to Fig. 27 (a), nano-sized particles having a particle diameter of about 100 to 150 nm were observed. As is apparent from Fig. 27 (b), a large amount of germanium atoms were detected in the dark portion observed in Fig. 27 (a). As can be seen from Fig. 27(c), a large amount of iron atoms were detected in the slightly bright spots observed in Fig. 27(a). As is clear from Fig. 27(d), a large amount of tin atoms were detected in the bright portion observed in Fig. 27(a). As is clear from Fig. 27(e), it is considered that the oxygen atomic system derived from oxidation is distributed over the entire nano-sized particles.

Figure 28 is a map further showing the results of EDS analysis. Fig. 28(a) is an EDS spectrum of Fe and Sn, and their superimposed views, and Fig. 28(b) is a HAADF-STEM image in the same field of view. According to Fig. 28(a), it is detected that the overlap of the places of Sn and Fe is small. In the XRD analysis, since the peak derived from the Sn-Fe alloy could not be confirmed, the Sn-Fe alloy was not formed in the Bennite size particles. Further, since Si and Sn are not alloyed, Sn is present as a monomer.

Fig. 29 is a graph showing the results of EDS analysis at the first to third places in the nanosized particle. In the first place of Fig. 29 (b), Si is mainly observed, and Sn is observed secondarily. Si and Sn were observed at the second place of Fig. 29 (c). At the third place of Fig. 29(d), Si and Fe are mainly observed, and Sn is observed secondarily. Further, the Cu background derived from the TEM mesh holding the sample was widely observed at the time of observation.

[Comparative Example 1]

Using a nanoparticle having an average particle diameter of 100 nm (manufactured by Hefei Kai'er NanoTech Co., Ltd.) instead of a nanosized particle as a negative electrode active material, a negative electrode E was produced in the same manner as in Example 1, and a battery for evaluation was constructed. Charge and discharge characteristics.

[Comparative Example 2]

As the test electrode, the negative electrode A produced in the same manner as in Example 1 was used, lithium was used for the counter electrode and the reference electrode, and a microporous film made of polyolefin was used as the separator. The electrolyte solution was made to have a carbonation scale of 1.3 mol/L of LiPF ₆ . An electrolyte solution of a mixed solution of ethyl ester (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) was used to constitute a battery for evaluation, and the charge and discharge characteristics were examined. That is, no vinylene carbonate (VC) was added to the electrolytic solution.

[Comparative Example 3]

The negative electrode B prepared in the same manner as in Example 2 was used as a test electrode, and then a battery for evaluation was constructed in the same manner as in Comparative Example 2, and the charge and discharge characteristics were examined.

[Comparative Example 4]

Using the negative electrode C prepared in the same manner as in Example 3 as a test electrode, a battery for evaluation was constructed in the same manner as in Comparative Example 2, and the charge and discharge characteristics were investigated.

[Comparative Example 5]

The negative electrode D prepared in the same manner as in Example 4 was used as a test electrode, and then a battery for evaluation was constructed in the same manner as in Comparative Example 2, and the charge and discharge characteristics were examined.

[Comparative Example 6]

The negative electrode E prepared in the same manner as in Comparative Example 1 was used as a test electrode, and then a battery for evaluation was constructed in the same manner as in Comparative Example 2, and the charge and discharge characteristics were examined.

(Evaluation of nanometer size particles)

Table 1 shows the powder electrical conductivity measured for the Si-based nano-sized particles of Examples 1 to 4 and Comparative Examples 1 to 6 by the method shown in Example 1 and the conditions of compressing the powder particles at 63.7 MPa.

The powder conductivity of Examples 1 to 4 and Comparative Examples 2 to 5 was 4 × 10 ^-8 [S/cm] or more, and the powder conductivity of Comparative Examples 1 and 6 was less than 4 × 10 ^-8 [S /cm]. Further, Comparative Examples 1 and 6 were smaller than the measurement limit of 1 × 10 ^-8 [S/cm]. If the conductivity of the powder is high, the formulation of the conductive auxiliary agent can be reduced, and the capacity per unit volume of the electrode can be increased, which is advantageous in terms of high efficiency characteristics.

The discharge capacity and capacity retention ratio of Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 2. Moreover, FIG. 30 shows the relationship between the number of cycles of Examples 1 to 4 and Comparative Examples 1 to 6 and the discharge capacity retention ratio.

As can be seen from Table 2 and FIG. 30, in Comparative Examples 1 to 4 and Comparative Examples 2 to 5, when VC was added to the electrolytic solution, the capacity retention ratio after the cycle was increased by 50 times or more. It is understood that the nonaqueous electrolyte secondary batteries of Examples 1 to 4 can suppress a decrease in capacity and have good cycle characteristics.

Next, it is understood that the results of Comparative Example 1 and Comparative Example 6 show that the above-described non-aqueous electrolyte secondary battery of the present invention has a preferable effect of suppressing the decrease in capacity obtained by adding VC to the electrolytic solution, but In addition to the inability to obtain all the effects of the non-aqueous electrolyte secondary battery using the nano-sized particles of Si as the negative electrode active material, the charge and discharge characteristics were also lowered.

In the present embodiment, as the negative electrode active material, Fe and Ni are used as the element M which forms the second phase with the compound of Si, and Sn is used as the element A which forms the third phase, but can be used for the negative electrode of the present invention. The active material is not limited to this. As long as it is a nano-sized particle of a second phase containing at least a first phase composed of Si and a compound MSi _X (1<X≦3) of the element M and Si, for example, Ti and Ni are used in addition to Fe and Ni. Co speculates that the same result can be obtained.

In the present embodiment, although vinylene carbonate is used as an organic substance capable of reduction polymerization in the molecule having an unsaturated bond, the organic substance which can be used for the reduction polymerization of the molecule having an unsaturated bond in the molecule is not limited. this. It is only necessary to reductively polymerize at the charge potential of the negative electrode, and a stable coating film can be formed on the surface of the negative electrode active material. For example, it is estimated that the same tendency as in the present embodiment can be obtained by using ethylene carbonate.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the examples. It is to be understood that various changes and modifications may be made without departing from the scope of the invention.

1. . . Nonaqueous electrolyte secondary battery

3. . . positive electrode

5. . . negative electrode

7. . . Separator

8. . . Non-aqueous electrolyte

9. . . First particle

10. . . Second particle

11. . . Nanosized particle

13. . . Phase 1

15. . . Phase 2

17. . . Nanosized particle

19. . . Another second phase

twenty one. . . Nanosized particle

twenty three. . . Phase 3

25. . . Battery can

27. . . Positive lead

29. . . Positive terminal

31. . . Negative wire

33. . . Sealing body

37. . . Nano-sized particle manufacturing device

39. . . Reaction chamber

41. . . Raw material powder supply port

42. . . Raw material powder

43. . . Protective gas supply port

44. . . Protective gas

45. . . Carrier gas

46. . . High frequency coil

47. . . High frequency power supply

49. . . Plasma

51. . . filter

53. . . mixer

55. . . Slurry

57. . . Slurry raw material

59. . . Applicator

61. . . Collector

Fig. 1 is a schematic cross-sectional view showing an example of a nonaqueous electrolyte secondary battery of the present invention.

Fig. 2 is a schematic view showing an example of the configuration of the negative electrode active material of the first embodiment.

3(a) to 3(c) are schematic cross-sectional views of the nanosized particle of the second embodiment.

4(a) and 4(b) are schematic cross-sectional views showing nanosized particles of the second embodiment.

Fig. 5 (a) and (b) are schematic cross-sectional views showing the nanosized particles of the second embodiment.

6(a) to 6(c) are schematic cross-sectional views of the nanosized particle of the third embodiment.

Fig. 7 (a) and (b) are schematic cross-sectional views showing the nanosized particles of the third embodiment.

Fig. 8 is a view showing the apparatus for producing nano-sized particles of the present invention.

Fig. 9 is a view showing a mixer for producing the negative electrode of the present invention.

Fig. 10 is a view showing an applicator for producing the negative electrode of the present invention.

Fig. 11 shows the results of XRD analysis of the nano-sized particles of Example 1.

Fig. 12 (a) is a BF-STEM photograph of the nano-sized particles of Example 1, and (b) is a HAADF-STEM photograph of the nano-sized particles of Example 1.

Fig. 13 (a) is a HAADF-STEM photograph of the first observation of the nanosized particle of Example 1, and (b) and (c) are EDS spectra of the same field of view.

Fig. 14 (a) is a HAADF-STEM photograph of the second observation of the nanosized particle of Example 1, and (b) and (c) are EDS spectra of the same field of view.

Figure 15 is a binary system state diagram of Fe and Si.

Fig. 16 is a result of XRD analysis of the nano-sized particles of Example 2.

17(a) and (b) are STEM photographs of the nano-sized particles of Example 2.

Fig. 18 (a) is a HAADF-STEM photograph of the first observation of the nano-sized particles of Example 2, and (b) to (d) are EDS spectra of the same field of view.

Fig. 19 (a) is a HAADF-STEM photograph of the second observation of the nanosized particle of Example 2, and (b) to (d) an EDS spectrum of the same field of view.

Fig. 20 is a result of XRD analysis of the nano-sized particles of Example 3.

Fig. 21 (a) is a BF-STEM photograph of the nano-sized particles of Example 3, and (b) is a HAADF-STEM photograph of the same field of view.

Figure 22 is a high resolution TEM photograph of the nano-sized particles of Example 3 of (a) to (c).

Fig. 23 (a) is a HAADF-STEM image of the nano-sized particles of Example 3, and (b) to (d) are EDS patterns of the same field of view.

Fig. 24 is a result of XRD analysis of the nanosized particle of Example 4.

Fig. 25 (a) is a BF-STEM photograph of the nano-sized particles of Example 4, and (b) is a HAADF-STEM photograph of the nano-sized particles of Example 4.

26(a) and (b) are HAADF-STEM photographs of the nano-sized particles of Example 4.

Fig. 27 (a) is a HAADF-STEM photograph of the nano-sized particles of Example 4, and (b) to (e) are EDS spectra of the same field of view.

Fig. 28 (a) is an EDS spectrum of the nano-sized particles of Example 4, and (b) a HAADF-STEM photograph of the same field of view.

Fig. 29 (a) is a HAADF-STEM photograph of the nano-sized particles of Example 4, (b) is the EDS analysis result at the first place in (a), and (c) is the second in (a) The EDS analysis result at the place, and (d) is the EDS analysis result at the third place in (a).

Fig. 30 is a graph showing the relationship between the number of cycles and the discharge capacity retention ratio of the nonaqueous electrolyte secondary batteries of the examples and the comparative examples.

1. . . Nonaqueous electrolyte secondary battery

3. . . positive electrode

5. . . negative electrode

7. . . Separator

8. . . Non-aqueous electrolyte

25. . . Battery can

27. . . Positive lead

29. . . Positive terminal

31. . . Negative wire

33. . . Sealing body

Claims (12)

A nonaqueous electrolyte secondary battery comprising: a positive electrode capable of occluding and releasing lithium ions; a negative electrode capable of occluding and releasing lithium ions; and a separator disposed between the positive electrode and the negative electrode, and The positive electrode, the negative electrode, and the separator are provided in a nonaqueous electrolytic solution having lithium ion conductivity, and the negative electrode active material of the negative electrode includes a first particle containing the element X and a second particle containing the element M, The element X is at least one element selected from the group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn, and the element M is composed of a transition metal element of Groups 4 to 11. One element selected from the group consisting of a monomer or a solid solution of the element X, and the second particle is composed of a monomer or a compound of the element M, and the electrolysis The liquid system contains 0.1% by weight to 10% by weight of an organic substance having an unsaturated bond in the molecule and capable of being reduced in polymerization. The nonaqueous electrolyte secondary battery according to claim 1, wherein the first particles have an average particle diameter of 2 nm to 500 nm, and the second particles have an average particle diameter of 2 nm to 10 μm. The nonaqueous electrolyte secondary battery according to claim 1, wherein the surface of the first particle is within 1 μm from the surface of the second particle. A non-hydrolyzed electrolyte secondary battery characterized in that it has a positive electrode capable of occluding and releasing lithium ions, a negative electrode capable of occluding and releasing lithium ions, and a separator disposed between the positive electrode and the negative electrode, and The positive electrode, the negative electrode, and the separator are provided in a non-aqueous electrolyte having lithium ion conductivity. The negative electrode active material of the negative electrode is composed of nano-sized particles containing an element X and an element M, and the element X is a group consisting of Si, Sn, Al, Pb, Sb, Bi, Ge, In, and Zn. One element selected, the element M being at least one element selected from the group consisting of transition metal elements of Groups 4 to 11, the nano-sized particles having at least the monomer of the aforementioned element X or The first phase of the solid solution and the monomer of the element M or the second phase of the compound, wherein the electrolyte solution contains 0.1% by weight to 10% by weight of an organic substance having an unsaturated bond in the molecule and capable of reduction polymerization. The non-hydrolyzed electrolyte secondary battery according to claim 4, wherein the first phase and the second phase of the nanosized particle are exposed to an outer surface and are bonded through an interface, and the first phase is externally The surface is generally spherical. The non-hydrolyzed electrolyte secondary battery of claim 4, wherein the nano-sized particles have an average particle diameter of from 2 nm to 500 nm. The non-hydrolyzed electrolyte secondary battery according to claim 4, wherein the nano-sized particle system further comprises an element M′ which is composed of Cu, Fe, Co, Ni, Ca, Sc, Ti, V, Cr, Mn. At least 1 selected from the group consisting of Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ba, lanthanide (except Ce and Pm), Hf, Ta, W, Re, Os, Ir The element M' is an element different from the type of the element M constituting the second phase, and further has a monomer or a further second phase of the compound M'. The non-hydrolyzed electrolyte secondary battery of claim 4, wherein the nano-sized particle system further comprises an element X' which is composed of Si, Sn, Al, At least one element selected from the group consisting of Pb, Sb, Bi, Ge, In, and Zn further has a monomer of the aforementioned element X' or a third phase of a solid solution. A non-hydrolyzable electrolyte secondary battery according to claim 8, wherein the third phase system is bonded to at least one of the first phase and the second phase. The non-hydrolyzed electrolyte secondary battery according to claim 1, wherein the first particle is a nano-sized particle of the fourth aspect of the patent application. The non-hydrolyzed electrolyte secondary battery according to claim 1 or 4, wherein the organic substance having an unsaturated bond in the molecule and capable of being reductively polymerized is a fluoroethylene carbonate, a vinylene carbonate and a derivative thereof, and At least one selected from the group consisting of ethylene carbonate. The non-hydrolyzed electrolyte secondary battery according to claim 1 or 4, wherein the negative electrode is formed by applying a coating liquid containing at least a negative electrode active material, a conductive material, and an adhesive material to a current collector and drying.