JP2019119638A - Silicon-based nanoparticle-containing hydrogen polysilsesquioxane, silicone oxide structure, and manufacturing method therefor - Google Patents

Abstract

To provide an anode material for secondary battery capable of further excellent capacity maintenance rate in a secondary battery, an anode active material for secondary battery, an anode for secondary battery, and a secondary battery.SOLUTION: There is provided a silicon oxide structure containing a silicon oxide skeleton containing Si and O in an atom composition, and a silicon-based nanoparticle chemically binding to the silicon oxide skeleton as constitutional elements, and having 50% cumulative mass particle diameter distribution diameter D50 of less than 3.0 μm.SELECTED DRAWING: Figure 5

Description

  The present invention relates to silicon-based nanoparticle-containing hydrogen polysilsesquioxane and silicon oxide structures in which the particle size of secondary aggregates is controlled within a predetermined range, and a method for producing them. Furthermore, the present invention relates to a negative electrode active material for a secondary battery including the silicon oxide structure, a negative electrode for a secondary battery including the negative electrode active material, and a secondary battery including the negative electrode for a secondary battery.

The development and progress of the lithium ion secondary battery starts with the creation of the basic technology of the lithium ion secondary battery developed by Yoshino et al. In 1985 (Patent Document 1). This lithium ion secondary battery uses a lithium compound (positive electrode active material) capable of releasing lithium ions at the positive electrode, and uses a carbonaceous material capable of absorbing and releasing lithium ions at the negative electrode. And since this secondary battery was developed, various types of lithium ion secondary batteries have been developed so far.
In particular, in recent years, with the rapid development of electronic devices and communication devices, the need for downsizing and weight reduction of such devices, and the spread of eco cars such as hybrid vehicles, a secondary having excellent battery characteristics such as higher capacity and longer life. There is a growing demand for battery development. In the development of secondary batteries excellent in such battery characteristics, technological development focusing on the improvement of the negative electrode is also active.

As a technique which paid its attention to the negative electrode, the negative electrode active material disclosed by patent document 2 is mentioned, for example. The negative electrode active material disclosed in Patent Document 2 is specifically a silicon oxide containing silicon and oxygen, and in particular, the atomic ratio of oxygen to silicon is 0 to 2, and X-ray diffraction using CuKα ray In the above, it has a predetermined pattern. More specifically, SiO particles of micrometer scale are heat-treated in a predetermined temperature range in a non-oxidizing atmosphere such as argon atmosphere or under reduced pressure to further reduce the amount of SiO ₂ present in large amounts on the surface of the particles to thereby obtain electrons. A step of reacting with a fluorine-containing compound or an alkaline aqueous solution is provided for the purpose of enhancing conductivity, and the silicon oxide specified by the above-mentioned predetermined measurement pattern is obtained. Patent Document 2 suggests that such a negative electrode active material can provide good charge / discharge cycle performance.

Furthermore, Patent Document 3 describes an amorphous silicon oxide that exhibits a predetermined binding energy, a predetermined silicon peak, and the like in an X-ray photoelectron spectrum, and a negative electrode active material including the same and a method for producing the same are disclosed. ing. Although this amorphous silicon oxide is expressed as SiO _x (0 <x <2), specifically, hydrogen polysil obtained by sol / gel reaction of a silane compound under an acid catalyst It is a baked product of sesquioxane. Patent Document 3 suggests that excellent charge / discharge characteristics are exhibited by using such a negative electrode active material. Although Patent Document 3 describes that amorphous silicon oxide represented by SiO _x (0 <x <2) is adopted, another silicon material is added in addition to hydrogen polysilsesquioxane. There is no mention or suggestion to add. Therefore, Patent Document 3 is substantially equivalent to the silicon oxide of SiO _x where x <1.5 and the method for producing the same.

  Further, Patent Document 4 discloses a negative electrode active material for non-carbon-based lithium ion secondary batteries, which includes a core containing silicon and silicon nanoparticles formed on the surface of the core, and a method for producing the same. . Specifically, in the negative electrode active material described in Patent Document 4, silicon oxide (SiO) and silicon nanoparticles are dispersed in an aqueous solution to which carboxymethyl cellulose or a dispersing agent is added, and mechanical such as ball milling is further performed. The silicon nanoparticles are attached to the surface of the silicon oxide by mixing using a stirring method and then removing the solvent through a drying process. In Patent Document 4, according to the configuration of such a silicon oxide, the decrease in the initial efficiency of the irreversible reaction due to lithium and oxygen generated at the time of initial charge is suppressed, and the increase in volume expansion coefficient at the time of charge and discharge It is mentioned that it can prevent.

  In addition, Patent Document 5 is a Chinese patent document, but the hydrolysis / coupling reaction of a silane coupling agent to the surface of nanoscale silicon particles, and 400 to 600 ° C. and 2 to 5 hours The negative electrode active material obtained by forming a SiO film through the sintering process of It is thought that Patent Document 5 suggests that such a negative electrode active material configuration can prevent inhibition of cycle stability due to volume expansion of the negative electrode. According to Patent Document 5, it can be said that the silane coupling agent of Patent Document 5 contains an organic functional group, and as a result, there is a high possibility that carbon is contained in the SiO film.

Japanese Patent Application Laid-Open No. 62-90863 JP 2004-71542 A JP, 2008-171813, A JP, 2016-514898, A CN105514382A

  By the way, the present inventors worked on research and development for the purpose of providing a more practical negative electrode active material while maintaining various battery performances in a more balanced manner than conventional negative electrode materials. As a result, we have developed a negative electrode active material that exhibits well-balanced and good battery characteristics to the extent that it can withstand practical use. Applicants have already completed patent applications for the same invention (Japanese Patent Application No. 2016-129861 and Japanese Patent Application No. 2017-2953). Specifically, the technology described in Japanese Patent Application No. 2016-129861 is composed of silicon-based nanoparticles, and silicon nanoparticles and a silicon oxide structure derived from hydrogen polysilsesquioxane have a chemical bond. , A silicon-based nanoparticle-containing hydrogen-polysilsesquioxane fired product having an atomic composition of Si-H bond and predetermined silicon (Si) / oxygen (O) / hydrogen (H) and containing essentially no carbon It is a technique which uses as a negative electrode material material.

  The present inventors are searching for a negative electrode material capable of exhibiting further excellent battery characteristics toward practical use of the above-described technology, and focusing on not only the chemical composition of the negative electrode material but also a predetermined physical structure, the battery characteristics In particular, it has been found that a negative electrode material capable of exhibiting further excellent characteristics in capacity retention rate can be manufactured. The present invention has been completed based on such findings. That is, the object of the present invention is to provide a negative electrode material for a secondary battery capable of exhibiting a further excellent capacity retention ratio in a secondary battery, and a negative electrode active material for a secondary battery using the same, a negative electrode for a secondary battery and a secondary battery To provide.

In order to solve the above problems, according to one aspect of the present invention, the following silicon oxide structure is provided.
[1] Silicon oxide skeleton containing Si and O in atomic composition,
Silicon-based nanoparticles chemically bonded to the silicon oxide skeleton;
Contains as a component,
50% cumulative mass particle size distribution diameter D50 in the particle size distribution is less than 3.0 μm,
Silicon oxide structure.

[2] The silicon oxide structure according to [1], wherein a secondary aggregate in which the silicon-based nanoparticles are collected as primary particles is formed.
[3] The silicon oxide structure according to [1] or [2], having a Si-H bond.

[4] The silicon oxide according to any one of [1] to [3], having an atomic composition represented by the general formula SiO _{x 2} H _{y 2} (0 <x2 <2, 0 <y2 <0.35) Object structure.
[5] It has an atomic composition represented by the general formula SiO _{x 2} H _{y 2} (0.3 <x2 <1.5, 0.01 <y2 <0.35), and has a Si—H bond, [1] The silicon oxide structure according to any one of [4].
[6] The silicon oxide structure according to any one of [1] to [5], which is essentially free of carbon.
[7] The silicon oxide structure according to any one of [1] to [6], wherein the volume-based average particle diameter of the silicon-based nanoparticle is 10 nm to 500 nm.
[8] The silicon oxide structure according to any one of [1] to [7], containing 5 to 65% by mass of the silicon-based nanoparticle.

[9] In the spectrum measured by infrared spectroscopy, the Si-O-Si bond in 1000 to 1200 ^-1 and the intensity of peak 1 _{(I 1)} derived from Si-H bonds in 820～920Cm ^-1 The silicon oxide according to any one of [1] to [8], wherein the ratio (I ₁ / I ₂ ) of the intensity (I ₂ ) of peak 2 derived therefrom is in the range of 0.01 to 0.35. Structure.
[10] In the spectrum measured by infrared spectroscopy, of the peak attributable to the bond of Si-O-Si, 1170Cm strength (peak 2-1) in the vicinity of ^-1 _{(I 2-1)} and 1070cm around ^-1 the silicon of the peak ratio of the intensity of the (peak _{2-2) (I 2-2) (I} 2-1 / I 2-2) is greater than 1, according to any one of [1] to [9] Oxide structure.
[11] The silicon oxide structure according to any one of [1] to [10], wherein the 50% cumulative mass particle size distribution diameter D50 is 2.0 μm or less.

Furthermore, according to another aspect of the present invention, the following negative electrode active material for a secondary battery is provided.
[12] A negative electrode active material for a secondary battery, comprising the silicon oxide structure according to any one of [1] to [11].

Furthermore, according to the further another aspect of this invention, the following negative electrode for secondary batteries is provided.
The negative electrode for secondary batteries containing the negative electrode active material for secondary batteries as described in [13] [12].

Furthermore, according to still another aspect of the present invention, the following secondary battery is provided.
[14] A secondary battery comprising the negative electrode for a secondary battery according to [13].

Furthermore, according to still another aspect of the present invention, the following method for producing a silicon oxide structure is provided.
[15] A method for producing a silicon oxide structure according to any one of [1] to [11], comprising the following steps (A) and (B):
(A) Hydrolysis and condensation reaction of a silicon compound represented by the following general formula (1) under the conditions of pH 2.95 or higher and in the presence of silicon-based nanoparticles, silicon-based nanoparticles containing hydrogen polysilsesquioxane To generate
HSi (R) ₃ (1)
(Wherein R represents identical or different, respectively, halogen, hydrogen, substituted or unsubstituted alkoxy having 1 to 10 carbons, substituted or unsubstituted aryloxy having 6 to 20 carbons, and 7 to 30 carbons) It is a group selected from substituted or unsubstituted arylalkoxy, provided that substituted or unsubstituted alkoxy having 1 to 10 carbon atoms, substituted or unsubstituted aryloxy having 6 to 20 carbon atoms, and 7 to 30 carbon atoms In the substituted or unsubstituted arylalkoxy of the above, any hydrogen may be substituted with a halogen); and (B) the silicon oxidation by firing the silicon-based nanoparticle-containing hydrogen polysilsesquioxane. Get the object structure.

[16] The method according to [15], wherein the hydrolysis and condensation reaction of the silicon compound is carried out in the step (A) under conditions of pH 3.0 to 7.0.
[17] In the step (A), the silicon compound is added to a dispersion of silicon-based nanoparticles to which an acid has been added so that the pH is 3.0 or more, and the silicon compound is hydrolyzed and condensed. The method as described in [15] or [16].
[18] The method according to [17], wherein the acid is at least one selected from the group consisting of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

[19] The method according to [17] or [18], wherein the acid is hydrochloric acid or acetic acid.
[20] The method according to any one of [15] to [19], wherein the step (B) is performed under a non-oxidizing atmosphere and at a temperature of 600 ° C to 900 ° C.
[21] The method according to [21], wherein the non-oxidizing atmosphere is a hydrogen gas atmosphere or a mixed gas atmosphere of 2 vol% or more of hydrogen gas and an inert gas.
[22] The silicon-based nanoparticle-containing hydrogen polysilsesquioxane has an atomic composition represented by the general formula SiO _x1 H _y1 (0.25 <x1 <1.35, 0.16 <y1 <0.90) The method according to any one of [15] to [21], having a chemical bond between the surface of the silicon-based nanoparticle and the hydrogen polysilsesquioxane.

Furthermore, according to still another aspect of the present invention, there is provided the following method for producing silicon-based nanoparticle-containing hydrogen polysilsesquioxane.
[23] A method of producing silicon-based nanoparticle-containing hydrogen polysilsesquioxane, comprising the following step (A):
(A) Hydrolysis and condensation reaction of a silicon compound represented by the following general formula (1) under the conditions of pH 2.95 or higher and in the presence of silicon-based nanoparticles, silicon-based nanoparticles containing hydrogen polysilsesquioxane To generate
HSi (R) ₃ (1)
(Wherein R represents identical or different, respectively, halogen, hydrogen, substituted or unsubstituted alkoxy having 1 to 10 carbons, substituted or unsubstituted aryloxy having 6 to 20 carbons, and 7 to 30 carbons) It is a group selected from substituted or unsubstituted arylalkoxy, provided that substituted or unsubstituted alkoxy having 1 to 10 carbon atoms, substituted or unsubstituted aryloxy having 6 to 20 carbon atoms, and 7 to 30 carbon atoms In the substituted or unsubstituted arylalkoxy, any hydrogen may be substituted with halogen).

[24] The method according to [23], wherein the hydrolysis and condensation reaction of the silicon compound is performed in the step (A) under conditions of pH 3.0 to 7.0.
[25] In the step (A), the silicon compound is added to a dispersion of silicon-based nanoparticles to which an acid is added so that the pH is 3.0 or more, and the silicon compound is hydrolyzed and condensed. The method according to [23] or [24].
[26] The method according to [25], wherein the acid is at least one selected from the group consisting of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.
[27] The method according to [25] or [26], wherein the acid is hydrochloric acid or acetic acid.
[28] The silicon-based nanoparticle-containing hydrogen polysilsesquioxane has an atomic composition represented by the general formula SiO _x1 H _y1 (0.25 <x1 <1.35, 0.16 <y1 <0.90) The method according to any one of [23] to [27], having a chemical bond between the surface of the silicon-based nanoparticle and the hydrogen polysilsesquioxane.

In addition, according to still another aspect of the present invention, the following silicon-based nanoparticle-containing polysilsesquioxane is provided.
[29] Silicon-based nanoparticle-containing hydrogen polysilsesquioxane produced by the method according to any one of [23] to [27].

[30] containing Si and O in atomic composition,
Further, it contains hydrogen polysilsesquioxane and silicon-based nanoparticles (preferably, silicon-based nanoparticles having a volume-based average particle diameter of preferably 10 nm to 500 nm) as primary particles,
It has a chemical bond between the surface of the silicon-based nanoparticle and the hydrogen polysilsesquioxane,
A secondary aggregate in which the silicon-based nanoparticles are assembled as primary particles is formed;
50% cumulative mass particle size distribution diameter D50 in the particle size distribution is less than 3.0 μm,
Silicon-based nanoparticle-containing hydrogen polysilsesquioxane.

[31] The silicon-based nanoparticle-containing hydrogen polysilsesquioxane according to [29] or [30], wherein the 50% cumulative mass particle size distribution diameter D50 is 2.0 μm or less.
[32] A compound represented by the general formula SiO _x1 H _y1 (0.25 <x1 <1.35, 0.16 <y1 <0.90), preferably containing 5 to 65% by mass of the above siliconanoparticles [ The silicon type nanoparticle containing hydrogen polysilsesquioxane as described in any one of 29]-[31].
[33] In the spectrum measured by infrared spectroscopy, of the peak attributable to the bond of Si-O-Si, 1170Cm strength ^-1 vicinity of the peak (peak 2-1) _{(I 2-1)} and 1070 cm ^-1 the ratio of the intensity around the peak (peak _{2-2) (I 2-2) (I} 2-1 / I 2-2) exceeds 1, according to any one of [29] - [32] Silicon-based nanoparticle-containing hydrogen polysilsesquioxane.

  According to the present invention, it is possible to exhibit various battery characteristics in a well-balanced manner in a secondary battery, and to secure a higher level of capacity maintenance rate.

FIG. 1 shows the results of measurement by infrared spectroscopy (IR) on the silicon nanoparticles containing hydrogen polysilsesquioxane (3) produced in Reference Example 5 and the hydrogen silsesquioxane polymer produced in Comparative Example 2 It is an IR absorption spectrum acquired as a result of performing. FIG. 2 is a scanning electron microscope (SEM) photograph of silicon nanoparticle-containing hydrogen polysilsesquioxane (3) produced in Reference Example 5. FIG. 3 shows the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (5), (8) and (9) manufactured in Reference Examples 10, 13 and 14, and the silicon nanoparticle mixture manufactured in Comparative Example 1 respectively. It is IR absorption spectrum acquired as a result of measuring by infrared spectroscopy (IR) about silicon oxide (1). FIG. 4 is a SEM photograph of the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (5) produced in Reference Example 10. FIG. 5 is a SEM photograph of silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (10) produced in Example 1 (a): 10,000 times, (b): 1,000 times! FIG. 6 is a particle size distribution of silicon nanoparticle-containing hydrogen polysilsesquioxane calcined products (10) and (13) manufactured in Example 1 and Comparative Example 5, respectively. FIG. 7 is a configuration example of a coin-type lithium ion battery.

<Silicon oxide structure>
A silicon oxide structure according to the present invention comprises, as components, a silicon oxide skeleton containing Si and O in atomic composition, and silicon-based nanoparticles chemically bonded to the silicon oxide skeleton. It is.
In the present invention, “a silicon oxide skeleton containing Si and O in atomic composition” means a chemical skeleton having at least a part of a silicon oxide structure composed of Si and O. More specifically, a chemical skeleton containing Si-O and Si-O-Si can be mentioned, and for example, silicon oxidation caused by heat treatment or firing of silicon-based nanoparticle-containing hydrogen polysilsesquioxane polymer described later It is a concept that also includes the skeleton of product structure.
Furthermore, in the present invention, as the term "silicon-based nanoparticles chemically bonded to silicon oxide skeleton" indicates, silicon-based nanoparticles are chemically bonded to the above-mentioned chemical skeleton as a whole. A silicon oxide structure is to be formed. Here, “the silicon-based nanoparticles are chemically bonded to the silicon oxide skeleton” means that the surface of the silicon-based nanoparticles is Si, for example, in the silicon oxide skeleton in the bonding mode of Si—O—Si. The form which has couple | bonded is mentioned. Since such chemical bonds are strong, the silicon oxide structure of the present invention has a structure or a property in which silicon-based nanoparticles are not easily detached from the structure.
In addition, in the silicon oxide structure of the present invention, formation of a secondary aggregate in which silicon-based nanoparticles are assembled is also a preferable embodiment as described later, but in the present invention, in particular, the silicon oxide The 50% cumulative mass particle size distribution diameter D50 of the structure is controlled to fall within a predetermined range.
According to the configuration as described above, first, the point of employing minimal primary particles (that is, nanometer-scale silicon-based nanoparticles), and the stress at the time of expansion and contraction that occurs when charging and discharging are repeated in the secondary battery Can be mitigated, cycle deterioration can be suppressed, and the effect of cycle characteristics improvement can be expected. Furthermore, since the silicon oxide structure adopting the above-mentioned structure has a network structure by the secondary aggregate formed by the aggregation of primary particles, the binding property with the binding agent becomes good, which is further excellent. It will exhibit cycle characteristics. In addition, the silicon oxide structure of the present invention as a whole has higher levels of 50% cumulative mass particle size distribution diameter D50 in the particle size distribution, in addition to the above effects. It becomes possible to secure a capacity maintenance rate.

  As described above, in the present invention, in particular, the particle size of the secondary assembly is controlled to a predetermined range. More specifically, the 50% cumulative mass particle size distribution diameter D50 in the particle size distribution of the silicon oxide structure is less than 3.0 μm. As a result of the 50% cumulative mass particle diameter distribution diameter D 50 being controlled within such a range, it is possible to secure a higher level of capacity retention rate in the secondary battery.

More specifically, the silicon oxide structure of the present invention has an atomic composition represented by SiO _{x 2} H _{y 2} (0.01 <x2 <2, 0 <y2 <0.35). Here, when y2 is 0, it means that hydrogen (H) is substantially absent. The silicon oxide structure of the present invention preferably has an atomic composition represented by SiO _{x 2} H _{y 2} (0.3 <x2 <1.5, 0.01 <y2 <0.35).

  The silicon oxide structure having the atomic composition as described above is not particularly limited as long as it is a range specified by the above configuration, but, for example, a silicon-based nanoparticle-containing hydrogen policy described in detail below A method for producing rusesquioxane and a method for producing a silicon-based nanoparticle-containing hydrogen polysilsesquioxane calcined product (hereinafter, both may be collectively referred to as “the method of the present invention”) Silicon-based nanoparticle-containing hydrogen polysilsesquioxane baked organisms are mentioned as an example. Hereinafter, specific embodiments of the production method of the present invention will be described, and the silicon oxide structure according to the present invention and the production method of the present invention will be described. The embodiment of the manufacturing method of the present invention and the embodiment of the silicon oxide structure according to the present invention are closely related to each other, and the components that can be adopted in the embodiment of the manufacturing method of the present invention are As long as there is no contradiction, it can be adopted in the embodiment of the silicon oxide structure.

<Production Process of Silicon Silicide-Containing Hydrogen Silsesquioxane Polymer>
The production method of the present invention comprises hydrolyzing and condensing a silicon compound described later under pH conditions of 2.95 or more and in the presence of silicon-based nanoparticles to produce silicon-based nanoparticles-containing hydrogen polysilsesquioxane (Step (A)) is included.

(Silicon based nanoparticles)
First, as the silicon-based nanoparticles, there is a concept including silicon nanoparticles consisting essentially of silicon, and nanoparticles (for example, composed of silica and silicon-based metal compound) containing silicon (silicon) in atomic composition It is. As long as the particle size (volume based average particle size) is in the nanometer scale range, it can be used, and is not particularly limited. When the final product is used as a negative electrode material of a secondary battery and the negative electrode thereof is used for a secondary battery, the volume-based average particle diameter (average particle diameter) of the silicon-based nanoparticles is, for example, 10 nm to 500 nm (or More than 10 nm and less than 500 nm), preferably from 30 nm to 200 nm (or more than 30 nm and 200 nm) is preferred. Use of such silicon-based nanoparticles having a relatively small average particle diameter suppresses cycle deterioration in the finally manufactured secondary battery, and can exhibit excellent cycle characteristics.
In the present invention, "volume-based average particle diameter" means that the particle diameter is calculated on a volume basis, and may be simply referred to as the average particle diameter.

  In addition, commercially available silicon nanopowders can also be used as silicon-based nanoparticles used in the present invention. Such silicon nanopowders may contain other components other than silicon. The silicon-based nanoparticles (silicon nanopowder) can contain, for example, metals and the like, but the content is usually less than 5% by mass with respect to the silicon-based nanoparticles.

(Silicon compound)
Next, silicon compounds to be subjected to hydrolysis and condensation reactions will be described. The silicon compound is a compound represented by the following general formula (1).
HSi (R) ₃ (1)
(Wherein R represents identical or different, respectively, halogen, hydrogen, substituted or unsubstituted alkoxy having 1 to 10 carbons, substituted or unsubstituted aryloxy having 6 to 20 carbons, and 7 to 30 carbons) A substituted or unsubstituted arylalkoxy group, provided that the substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, the substituted or unsubstituted aryloxy group having 6 to 20 carbon atoms, and the 7 carbon atoms In the substituted or unsubstituted arylalkoxy group, any hydrogen may be substituted with halogen).

Specific examples of the silicon compound represented by the formula (1) include the following compounds.
For example, trihalogenated silanes such as trichlorosilane, trifluorosilane, tribromosilane, dichlorosilane and the like, dihalogenated silanes, tri-n-butoxysilane, tri-t-butoxysilane, tri-n-propoxysilane, tri-i Trialkoxysilanes such as propoxysilane, di-n-butoxyethoxysilane, triethoxysilane, trimethoxysilane, diethoxysilane and dialkoxysilanes, and further triaryloxysilanes, diaryloxysilanes, diaryloxyethoxysilanes and the like There may be mentioned aryloxysilane or aryloxyalkoxysilane.

  Among these, trihalogenated silanes or trialkoxysilanes are preferable from the viewpoint of good reactivity, easy availability and inexpensive production cost, and trihalogenated silanes are particularly preferable.

  The above silicon compounds may be used alone or in combination of two or more.

  The silicon compounds as described above have high hydrolyzability and condensation reactivity, and when using them in step (A), the above-mentioned predetermined silicon-based nanoparticle-containing hydrogen polysilsesquioxane can be easily obtained. In addition, the silicon-based nanoparticle-containing hydrogen polysilsesquioxane thus obtained in the step (B) in the process for producing a silicon-based nanoparticle-containing hydrogen-polysilsesquioxane calcined product according to the present invention described below is not added. In heat treatment under an oxidizing atmosphere, there is also an advantage that it is easy to control the amount of Si-H bonds in the silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product finally obtained.

(Conditions of hydrolysis and polycondensation reaction)
Next, the conditions of the hydrolysis and polycondensation reaction in step (A) will be described in detail.
In the step (A), for example, the mixture of the silicon compound and the silicon-based nanoparticle may be hydrolyzed and subjected to a condensation reaction under the predetermined pH conditions. Alternatively, the following method can also be adopted. First, a dispersion of the silicon-based nanoparticles is prepared, and an acid or a base is added to the dispersion to adjust the pH of the dispersion to the predetermined range. Then, the hydrolysis and condensation reaction of the silicon compound can be advanced by adding the silicon compound to the dispersion.

  Furthermore, as a dispersion liquid of the silicon-based nanoparticles, a mixture of the silicon-based nanoparticles and a predetermined solvent (described later) is subjected to ultrasonic treatment or the like to uniformly disperse the silicon-based nanoparticles in the solvent. Dispersions of the prepared silicon-based nanoparticles can be used. More specifically, an acid or base and optionally a predetermined solvent are further added to the dispersion of silicon-based nanoparticles thus obtained, and a dispersion showing a pH within the above-mentioned predetermined range by mixing It can be done.

More specifically, for example, in addition to water, silicon-based nanoparticles are added to an organic solvent such as alcohol, acetone, hexane, DMF or the like, or a mixed solvent thereof, and a predetermined acid is added to the solution pH. The hydrolysis and polycondensation reaction of the silicon compound can be advanced by adding (for example, dropping) the silicon compound represented by the general formula (1) to the solution after adjusting to the above predetermined range. . Furthermore, the hydrolysis and polycondensation reaction may be performed at normal temperature (room temperature) or may be performed in a heated state.
That is, in addition to the hydrolyzate of the silicon compound represented by Formula (1), the reaction liquid after hydrolysis may contain an acid, water, other solvents, and substances derived therefrom.

Moreover, in the reaction liquid after hydrolysis, the silicon compound finally represented by Formula (1) may not be completely hydrolyzed, and the one part may remain | survive.
In addition to the hydrolysis reaction, the polycondensation reaction of the hydrolyzate also partially proceeds.
Here, the degree to which the polycondensation reaction proceeds can be controlled by the hydrolysis temperature, hydrolysis time, acidity, and / or solvent etc. For example, as described later, the target silicon-based nanoparticle-containing It can be appropriately set according to hydrogen polysilsesquioxane.

In the present invention, in consideration of the productivity and the production cost, it is preferable to carry out the hydrolysis and the polycondensation reaction in one reactor under the same conditions in parallel.
As a reaction condition, the silicon compound represented by the formula (1) is added to the silicon-based nanoparticle dispersion liquid adjusted to be within the above-mentioned predetermined pH range under stirring, −20 ° C. to 50 ° C. The reaction is preferably carried out at a temperature of 0 ° C. to 40 ° C., particularly preferably 10 ° C. to 30 ° C., for 0.5 hour to 20 hours, preferably 1 hour to 10 hours, particularly preferably 1 hour to 5 hours. Furthermore, the addition of the silicon compound represented by Formula (1) to the silicon-based nanoparticle dispersion liquid is not particularly limited, and may be added at once or in small amounts over a plurality of times. Although it may be added, it is convenient to add by adding a small number of times over several times.

  The lower limit value of the pH of the silicon-based nanoparticle dispersion (reaction liquid) is, as described above, about 2.95 or more, preferably 3.0 or more, more preferably 3.1 or more, 3.2 or more. In some cases, for example 3.4 or more, 3.5 or more, 3.6 or more, 3.7 or more, 3.8 or more, 3.9 or more, 4.0 or more. The upper limit value of pH is not particularly limited, but it is usually preferably adjusted to about 7.0 or less, more preferably 6.0 or less, for example, 5.0 or less.

  Furthermore, as a range of pH that can be adopted in the present invention, a range of pH obtained by arbitrarily combining the lower limit value and the upper limit value of the above-mentioned pH can be mentioned, and in particular, silicon-based nanoparticle-containing hydrogen polysil In the sesquioxane calcined product, the pH range can be selected such that the 50% cumulative mass particle size distribution diameter D50 in the particle size distribution of the calcined product (silicon oxide structure) is 3 μm or less. The pH range is, for example, 2.95 to 7.0, preferably 3.0 to 7.0, more preferably 3.2 to 7.0, still more preferably 3.3 to 7.0, and still more preferably Preferably, 2.95 to 6.0, preferably 3.0 to 6.0, more preferably 3.2 to 6.0 can be mentioned.

As an acid which can be used for pH adjustment of a reaction liquid, both an organic acid and an inorganic acid can be used.
Specific examples of the organic acid include formic acid, acetic acid, propionic acid, oxalic acid, and citric acid, and examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. Among these, it is preferable to use hydrochloric acid and acetic acid because the hydrolysis reaction and the subsequent polycondensation reaction can be easily controlled, the cost is low, and the treatment after the reaction is easy.

  Furthermore, in general, the hydrolysis solution is generally adjusted to the acidic side, but in order to realize various physical properties in the obtained silicon-based nanoparticle-containing hydrogen polysilsesquioxane and its calcined product, the alkali side is preferably used. It is assumed that some adjustment may be necessary. In that case, sodium hydroxide, calcium hydroxide, potassium hydroxide, ammonia etc. are mentioned as a base used for pH adjustment.

  In addition, when a halogenated silane such as trichlorosilane is used as the silicon compound represented by the formula (1), an acidic aqueous solution is formed in the presence of water, so that it is not necessary to add an acid separately, Such an embodiment is one of the preferred embodiments of the present invention.

  The amount of the silicon-based nanoparticles is not particularly limited, but is usually blended so as to be 5% by mass to 65% by mass with respect to the obtained silicon-based nanoparticles-containing hydrogen polysilsesquioxane. Preferably, it is 10% by mass to 60% by mass. When the fired product is used as a negative electrode active material of a lithium ion battery at 5% by mass or more, the initial charge / discharge efficiency is high, and the effect of being complexed with silicon-based nanoparticles can be obtained sufficiently and reliably. In addition, when the amount of silicon-based nanoparticles is 65% by mass or less, when it is used as a negative electrode active material of a lithium ion battery, the negative electrode active by charge and discharge due to stress relaxation of complexed hydrogen silsesquioxane The expansion and contraction rate of the substance does not increase, and the capacity retention rate can be sufficiently maintained.

  In the production method of the present invention, after silicon-based nanoparticle-containing hydrogen polysilsesquioxane is produced through hydrolysis reaction and polycondensation reaction in addition to step (A), filtration separation, centrifugation or A step may be provided in which the liquid fraction is separated and removed by a method such as tilting, and the obtained solid fraction is made into silicon-based nanoparticle-containing hydrogen polysilsesquioxane. As various solid-state techniques are known to those skilled in the art, methods for separating such solid content and liquid can be used as appropriate. Furthermore, in some cases, the obtained solid fraction may be provided with a step of washing with water or washing with an organic solvent and drying.

<Structure of Silicon-Based Nanoparticle-Containing Hydrogen Polysilsesquioxane>
The composition of the silicon-based nanoparticle-containing hydrogen polysilsesquioxane obtained as described above contains silicon (Si), oxygen (O) and hydrogen (H), as determined by elemental analysis, and has the general formula SiO represented by _{x1 H y1 (0.25 <x1 <} 1.35,0.16 <y1 <0.90). Furthermore, the silicon-based nanoparticle-containing hydrogen polysilsesquioxane is essentially free of carbon. Furthermore, as described above, in the generation reaction of silicon-based nanoparticle-containing hydrogen polysilsesquioxane, since excessive aggregation of silicon-based nanoparticles is suppressed by controlling the pH, silicon-based nano The relatively small particle size of secondary aggregates formed by particle aggregation is a scanning electron micrograph (Figs. 2, 4 and 5) and corresponding of silicon nanoparticles-containing hydrogen polysilsesquioxane calcined product. It is inferred from the particle size analysis results of the embodiments.

Furthermore, by firing silicon-based nanoparticle-containing hydrogen polysilsesquioxane in the range of 0.25 <x1 <1.35, preferably 0.28 <x1 <1.3 in the general formula SiO _x1 H _y1 With sufficient battery capacity, it is possible to obtain a sintered body (negative electrode active material) having excellent charge and discharge characteristics in which the initial charge and discharge efficiency and the cycle capacity retention ratio are well balanced. Furthermore, if 0.16 <y1 <0.90, preferably 0.16 <y1 <0.86, it can be obtained using a calcined product of silicon-based nanoparticle-containing hydrogen polysilsesquioxane The secondary battery has excellent cycle characteristics with improved charge and discharge capacity and capacity retention rate.

Furthermore, the silicon-based nanoparticle-containing hydrogen polysilsesquioxane of the present invention has 1170 cm ^{− of} peaks derived from the Si—O—Si bond in consideration of the spectrum measured by infrared spectroscopy in the following reference examples. The ratio (I _2-1 / I _2-2 ) of the intensity (I _2-1 ) of peak 2-1 near ¹ and the intensity (I _2-2 ) of peak 2-2 near 1070 cm ^-1 is 1 It is thought that it exceeds. The fact that the above peak intensity ratio exceeds 1 indicates that there is a chemical bond between the silicon-based nanoparticle present inside and the hydrogen polysilsesquioxane, and this chemical It is assumed that the presence of the bond suppresses particle collapse caused by expansion and contraction of silicon particles during charge and discharge cycles.

  According to the SEM photographs shown in FIGS. 2 and 4, the silicon-based nanoparticle-containing hydrogen polysilsesquioxane thus obtained has a number of particles due to aggregation of primary particles which are spherical particles having a particle diameter of submicron. It is observed that micron secondary aggregates are formed. Furthermore, in consideration of the SEM photograph of the silicon-based nanoparticle-containing hydrogen polysilsesquioxane shown in FIG. 5, the particle size of the secondary aggregate in the silicon-based nanoparticle-containing hydrogen polysilsesquioxane of the present invention Is considered to be smaller than the particle size of secondary aggregates in silicon nanoparticles-containing hydrogen polysilsesquioxane (hereinafter, synthesized in the reference example) disclosed in Japanese Patent Application Nos. 2016-129861 and 177641. Ru.

  Furthermore, because the primary particles are small, when the fired product of the silicon-based nanoparticle-containing hydrogen polysilsesquioxane is used as a negative electrode material of a secondary battery such as a lithium ion battery, the expansion occurs when charging and discharging are repeated. The relaxation of the stress at the time of contraction is effective in improving the cycle characteristics to suppress the cycle deterioration. In addition, by having a complex secondary structure, the binding property with the binding agent becomes good, and further excellent cycle characteristics are expressed.

Silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product and method for producing the same
Next, a silicon-based nanoparticle-containing hydrogen polysilsesquioxane obtained by firing a recon nanoparticle-containing hydrogen-polysilsesquioxane fired product to be obtained will be described.
The method for producing a silicon-based nanoparticle-containing hydrogen polysilsesquioxane calcined product of the present invention comprises the silicon-based nanoparticle-containing hydrogen polysilate produced as described above as the step (B) in addition to the step (A). In the following, baking of sesquioxane is included to obtain a silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product, which is one form of the “silicon oxide structure” in the present invention.
That is, the silicon-based nanoparticle-containing hydrogen polysilsesquioxane calcined product obtained in the step (B) is specified by the following configuration as described at the beginning.
(I) comprising, as constituents, a silicon oxide skeleton containing Si and O in atomic composition, and silicon-based nanoparticles chemically bonded to the silicon oxide skeleton;
(Ii) 50% cumulative mass particle size distribution in particle size distribution D50 is less than 3.0 μm.

In the step (B), the silicon-based nanoparticle-containing hydrogen polysilsesquioxane obtained in the above-mentioned step (A) is obtained, for example, by heat treatment in a non-oxidative atmosphere.
In the present invention, “non-oxidizing atmosphere” refers to carbon dioxide when the silicon-based nanoparticle-containing hydrogen polysilsesquioxane is heat-treated such that the silicon oxide structure satisfies the above conditions (i) to (iii). It is sufficient if the atmosphere is such that the formation of silicon is controlled. More specifically, the "non-oxidative atmosphere" may be any atmosphere in which oxygen is substantially removed to such an extent that the silicon oxide structure satisfies the above conditions (i) to (iii). It means that. Furthermore, in this case, it is preferable that the value of I ₁ / I ₂ falls within the predetermined range described below.
Here, I ₁ refers to the intensity (I ₁ ) of peak 1 located at 820 to 920 cm ⁻¹ and derived from Si—H bond. In addition, I ₂ refers to the strength (I ₂ ) that is at 1000-1200 cm ⁻¹ and is derived from Si—O—Si bonds. In such a particularly preferred embodiment, analysis of the atomic composition of the silicon-based nanoparticle-containing hydrogen polysilsesquioxane sintered product produced includes silicon (Si), oxygen (O) and hydrogen (H). It is represented by the general formula SiO _{x 2} H _{y 2} (0.3 <x2 <1.5, 0.01 <y2 <0.35) and essentially free of carbon.

  In the case of a silicon oxide structure (baked product), if the range of 0.3 <x2 <1.5, preferably 0.4 <x2 <1.0, the initial charge and discharge efficiency is sufficient with sufficient battery capacity. It is possible to realize a negative electrode active material having a balance with the cycle capacity retention rate and excellent charge / discharge characteristics. In the silicon oxide structure (baked product), when the range of 0.01 <y2 <0.35, preferably 0.01 <y2 <0.3, the obtained secondary battery has excellent charge and discharge capacity. And good cycle characteristics with improved capacity retention rate.

Furthermore, the silicon oxide structure (calcined product) has an intensity (I ₁ ) of peak 1 at 820 to 920 cm ⁻¹ and derived from Si—H bond in the spectrum measured by infrared spectroscopy (IR) it is preferred that the ratio of 1000~1200cm located to ^-1 and Si-O-Si peak intensity 2 derived from the binding _{(I 2) (I 1 /} I 2) is in the range of 0.01 to 0.35.

Silicon oxide structure ratio of the intensity _{(I 1)} and the intensity of peak 2 peak 1 (calcined _{product) (I 2) (I 1} / I 2) is more preferably from 0.01 0.30 More preferably, if it is in the range of 0.03 to 0.20, high discharge capacity, good initial charge / discharge efficiency and cycle when made into a negative electrode active material of a lithium ion battery due to the presence of a suitable amount of Si-H bond Properties can be expressed.

Furthermore, in the spectrum measured by infrared spectroscopy, the silicon oxide structure (baked product) shows that the intensity of the peak 2-1 near 1170 cm ⁻¹ among the peaks derived from the Si—O—Si bond (I ₂ Preferably, the ratio (I _2-1 / I _2-2 ) of the intensity (I _2-2 ) of the peak 2-2 near _{1 10 7} and 1070 cm ^-1 exceeds 1. The peak intensity ratio of more than 1 means that the silicon-based nanoparticles present inside the silicon-based nanoparticles-containing hydrogen polysilsesquioxane fired product and the skeleton of the silicon oxide structure derived from hydrogen polysilsesquioxane. It is suggested that there is a chemical bond between them, and it is presumed that the presence of this chemical bond suppresses particle collapse caused by expansion and contraction of silicon particles during charge and discharge cycles.

As described above, the heat treatment of the silicon-based nanoparticle-containing hydrogen polysilsesquioxane obtained in the step (A) is preferably performed in a non-oxidative atmosphere. When heat treatment is performed in an atmosphere in which oxygen is present, silicon dioxide is generated, which may make it impossible to obtain the desired composition and the amount of Si—H bonds.
As a non-oxidizing atmosphere, an atmosphere in which oxygen is removed by an inert gas atmosphere or high vacuum (oxygen is removed to such an extent that generation of the target silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product is not inhibited Any atmosphere may be included, a reducing atmosphere and an atmosphere in which these atmospheres are used in combination. The inert gas may, for example, be nitrogen, argon or helium. These inert gases can be used without any problem as long as they are of high purity standard generally used. Moreover, the atmosphere which removed oxygen by high vacuum may be sufficient, without using inert gas. As the reducing atmosphere, an atmosphere containing a reducing gas such as hydrogen is included. For example, a mixed gas atmosphere of 2% by volume or more of hydrogen gas and inert gas can be mentioned. In addition, a hydrogen gas atmosphere can also be used as a reducing atmosphere.

In the present invention, by performing heat treatment in a non-oxidizing atmosphere, dehydrogenation of Si—H bond starts from about 600 ° C. of silicon-based nanoparticle-containing hydrogen polysilsesquioxane, and Si—Si bond is generated, A characteristic silicon oxide structure derived from hydrogen polysilsesquioxane is formed. Even after this heat treatment, the chemical bond between the silicon-based nanoparticles and the hydrogen polysilsesquioxane is maintained. The presence of a silicon oxide structure derived from hydrogen polysilsesquioxane after heat treatment can be known from the measurement by infrared spectroscopy described later, and the like. When grown appropriately, the Si-Si bond is a good Li storage site and a source of high charge capacity. On the other hand, the Si-H bond interacts with a binder having a functional group such as a COO ^- group, which is a known battery material component, to form a flexible and strong bond, so that in the case of a battery, Express good cycle characteristics.
Therefore, it is necessary to leave an appropriate amount of Si-H bonds to achieve both high capacity and good cycle characteristics, and the heat treatment temperature to satisfy such conditions is usually 600 ° C. to 1000 ° C., preferably 750 ° C. To 900 ° C. At less than 600 ° C. Too many Si-H bonds, the discharge capacity is not sufficient, 1000 good cycle characteristics for ° C. exceeds the Si-H bonds to disappear can not be obtained, rigid SiO ₂ further surface There is a tendency that the layer develops and the capacity is less likely to be developed because it inhibits the insertion and detachment of lithium.
The heat treatment time is not particularly limited, but is usually 30 minutes to 10 hours, preferably 1 to 8 hours.

By appropriately adjusting the conditions of the above heat treatment, it is possible to obtain a silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product which is one embodiment of the silicon oxide structure of the present invention. That is, the heat treatment conditions may be appropriately adjusted so that the silicon oxide structure obtained by the heat treatment contains Si and O in the atomic composition. Furthermore, preferably, the silicon oxide structure obtained by the heat treatment is SiO _{x 2} H _{y 2} (0.01 <x2 <2, preferably 0.3 <x2 <1.5, more preferably 0.4 <x2 < The heat treatment conditions are appropriately adjusted to have an atomic composition of 1.0; and 0 <y2 <0.35, preferably 0.01 <y2 <0.35, more preferably 0.01 <y2 <0.3). Preferably. In addition, particularly preferably, the silicon oxide structure obtained by heat treatment has these atomic compositions, and the intensity of peak 1 (I ₁ ) and the intensity of peak 2 (I) measured by infrared spectroscopy. _The heat treatment conditions are appropriately selected such that the ratio (I ₁ / I ₂ ) to ₂ ) falls within the range of 0.01 to 0.35, preferably 0.01 to 0.30, 0.03 to 0.20. Good. When the atomic composition and / or peak ratio I ₁ / I _{2 of the} silicon oxide structure is in such a predetermined range, higher battery capacity is ensured, and further, the balance between the initial charge / discharge efficiency and the cycle capacity retention rate This is because the negative electrode active material exhibiting excellent charge and discharge characteristics can be obtained with high reliability.

  The silicon-based nanoparticle-containing hydrogen polysilsesquioxane calcined product of the present invention thus obtained, that is, the silicon oxide structure, has as its shape the silicon-based nanoparticle-containing hydrogen polysilsesqui obtained by the synthesis method of the present invention. Since it is obtained by heat-treating oxane, as is apparent from the SEM photograph shown in FIG. 5, a secondary aggregate in which primary particles having spherical particles with a submicron particle size can be observed. The particle size or particle size of such secondary assemblies can be observed on the nanometer scale to several microns or so. More specifically, in the silicon oxide structure of the present invention, secondary aggregation with a particle size or particle size of less than 3.0 μm is observed by SEM observation, more preferably 2.9 μm or less, 2.6 μm or less The particle size of 2.5 μm or less, more preferably 2.4 μm or less, still more preferably 2.3 μm or less, 2.2 μm or less, 2.1 μm or less, 2.0 μm or less, 1.9 μm or less, 1.8 μm or less Or secondary aggregates of particle size can be observed.

  And, particularly in the production method of the present invention, when producing silicon-based nanoparticles-containing hydrogen polysilsesquioxane, the silicon particles which are primary particles are controlled by controlling the pH which is one of the reaction conditions within the above-mentioned predetermined range. The aggregation of the nanoparticles is suppressed to a certain extent, and as a result, the increase in the particle size of the secondary aggregate, which is an aggregate of primary particles, is also suppressed to a certain extent. As a result, in the silicon-based nanoparticle-containing hydrogen polysilsesquioxane calcined product (silicon oxide structure) of the final product, the 50% cumulative mass particle size distribution diameter D50 in the particle size distribution is less than 3.0 μm.

Here, the 50% cumulative mass particle diameter distribution diameter D50 is preferably 2.9 μm or less, 2.6 μm or less, 2.5 μm or less, more preferably 2.4 μm or less, still more preferably 2.3 μm or less, It is 2.2 micrometers or less, 2.1 micrometers or less, 2.0 micrometers or less, 1.9 micrometers or less, and 1.8 micrometers or less.
When the 50% cumulative mass particle diameter distribution diameter D50 is in the above range, cycle deterioration is suppressed at a higher level in the secondary battery, and cycle characteristics can be further improved.

  In the present invention, the lower limit of the 50% cumulative mass particle size distribution diameter D50 is naturally determined by the aggregation or aggregation of the silicon-based nanoparticles in view of using the silicon-based nanoparticles having a particle size of nanometer scale in the present invention. It is not particularly limited because the desired effects can be obtained as long as the above upper limit is not exceeded. For example, the lower limit may be 300 nm or more, 400 nm or more, 500 nm or more, 600 nm or more, 700 nm or more, 800 nm or more, 900 nm or more, or 1.0 μm or more.

Furthermore, in addition to the fact that the particle size of the secondary assembly is controlled within a certain range, as described above, the primary particle of the silicon-based nanoparticle in the present invention is on the nanometer scale. Since the stress at the time of expansion and contraction that occurs when repeating charge and discharge is further alleviated when used in the above, not only the particle size of the secondary assembly but also the particle size of the primary particles, the cycle deterioration suppression and cycle characteristics Contribute to improvement.
In addition, it may be said that the binding property with the binding agent is improved by having a complex secondary structure as described above, and further excellent cycle characteristics are exhibited.

<Anode Active Material Containing Silicon Oxide Structure>
Next, a negative electrode active material containing a silicon oxide structure (specifically, the above-mentioned silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product) will be described.

Since the battery is required to have a high capacity and to be charged and discharged with a large current, a material having a low electric resistance of the electrode is required.
Therefore, it is also an aspect of the present invention to composite or coat a carbon-based material on the silicon oxide structure.
In order to composite or coat the carbon-based material, a method of dispersing the silicon oxide structure and the carbon-based material by mechanical mixing method using a mechanofusion, a ball mill, a vibration mill or the like may be mentioned.

  Preferred examples of the carbon-based material include carbon-based materials such as graphite, carbon black, fullerene, carbon nanotube, carbon nanofoam, pitch-based carbon fiber, polyacrylonitrile-based carbon fiber and amorphous carbon.

  The silicon oxide structure and the carbon-based material can be combined or coated at any ratio.

<Negative electrode>
The negative electrode for a secondary battery according to the present invention is a silicon oxide structure (specifically, the above-mentioned silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product) or a silicon oxide composited or coated with the above-mentioned carbon-based material. It is manufactured using the negative electrode active material containing a structure.
For example, the negative electrode is formed based on a method of forming a negative electrode mixed material containing the above-mentioned negative electrode active material and optionally a binder into a predetermined shape, or a method of applying the negative electrode mixed material to a current collector such as copper foil. It may be manufactured. The negative electrode may be formed by any method without particular limitation, and various known methods may be used.

  More specifically, for example, first, a negative electrode active material including a silicon oxide structure obtained by compounding or coating the above silicon oxide structure or a carbon-based material, and various additives such as a binder and a conductive material as required. A composition for a secondary battery negative electrode is prepared. The prepared composition for a secondary battery negative electrode may be directly coated on a current collector such as a rod-like body, a plate-like body, a foil-like body or a net-like body mainly composed of copper, nickel, stainless steel or the like. Alternatively, the composition for a secondary battery negative electrode is separately cast on a support, the negative electrode active material film formed on the support is peeled off, and the peeled negative electrode active material film is laminated on a current collector. A negative electrode plate may be formed. In addition, said form is an illustration to the last, It can not be overemphasized that the negative electrode of this invention is not limited to these, and may be provided as another form.

As the binder, those commonly used in the secondary battery, a Si-H bonds and interactions on the anode active material, COO ^- as long as having a functional group such as a group, either Are also available. Specifically, in addition to carboxymethyl cellulose, polyacrylic acid, alginic acid, glucomannan, amylose, sucrose and derivatives and polymers thereof, and respective alkali metal salts, polyimide resins and polyimide amide resins are exemplified. These binders may be used alone or in combination of two or more.
Furthermore, in addition to the binder, for example, the binding property between the current collector and the negative electrode active material is improved, the dispersibility of the non-permissive substance is improved, and the conductivity of the binder itself is improved. Additives that can impart functions can also be added as needed. Specific examples of such additives include styrene-butadiene rubber polymers, styrene-isoprene rubber polymers, and the like.

<Secondary battery>
The secondary battery according to the present invention may be appropriately designed in consideration of the desired application, function, etc., and the configuration thereof is not particularly limited, but the present secondary battery is referred to with reference to the configuration of the existing secondary battery. A secondary battery can be configured using the negative electrode according to the invention. In addition, the type of secondary battery of the present invention is not particularly limited as long as the negative electrode of the present invention can be applied, but, for example, a lithium ion secondary battery and a lithium ion polymer secondary battery are mentioned Be These batteries are said to be particularly preferred embodiments because the desired effects of the present invention can be exhibited as demonstrated in the following examples.
Hereinafter, the manufacturing method and structure of a lithium ion battery are illustrated.

First, a positive electrode active material composition is prepared by mixing a positive electrode active material capable of reversibly absorbing and desorbing lithium ions, a conductive additive, a binder and a solvent. Similar to the negative electrode, the positive electrode active material composition is directly coated and dried on a metal current collector using various methods to prepare a positive electrode plate.
It is also possible to separately cast the above positive electrode active material composition on a support, peel off the film formed on the support, and laminate the same film on a metal current collector to produce a positive electrode. . Although the shaping | molding method of a positive electrode is not specifically limited, It can form using various well-known methods.

As said positive electrode active material, lithium metal complex oxide generally used in the field | area of the said secondary battery can be used. For example, lithium cobaltate, lithium nickelate, lithium manganate having a spinel structure, lithium cobalt manganate, iron phosphate having an olivine structure, so-called ternary lithium metal composite oxide, nickel lithium metal composite oxide Etc. In addition, V ₂ O ₅ , TiS and MoS, which are compounds capable of lithium ion de-insertion, can also be used.

A conductive aid may be added, and those generally used in lithium ion batteries can be used. It is preferable that it is an electron conductive material which does not cause decomposition or deterioration in the manufactured battery. Specific examples thereof include carbon black (acetylene black and the like), graphite fine particles, vapor grown carbon fibers, and a combination of two or more of them. Further, as the binder, for example, vinylidene fluoride / propylene hexafluoride copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene and mixtures thereof, styrene butadiene rubber Although a system polymer etc. are mentioned, it is not limited to these. Moreover, as a solvent, although N- methyl pyrrolidone, acetone, water etc. are mentioned, for example, it is not limited to these.
At this time, the contents of the positive electrode active material, the conductive additive, the binder and the solvent are not particularly limited, but the amounts generally used in lithium ion batteries can be appropriately selected as a standard. .

As a separator interposed between the positive electrode and the negative electrode, a separator generally used in a lithium ion battery may be used, but it is not particularly limited, and it is appropriately determined in consideration of a desired application, a function, etc. It should be selected. It is preferable that the electrolyte has low resistance to ion migration or is excellent in electrolytic solution impregnating ability. Specifically, it is a material selected from glass fiber, polyester, polyethylene, polypropylene, polytetrafluoroethylene, polyimide, or a compound thereof, and may be in the form of non-woven fabric or woven fabric.
More specifically, in the case of a lithium ion battery, a windable separator made of a material such as polyethylene or polypropylene is used, and in the case of a lithium ion polymer battery, a separator excellent in organic electrolyte impregnation ability It is preferred to use

As an electrolytic solution, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butylene carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4 -Hexafluoride in a solvent such as methyldioxolane, N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene or diethyl ether or a mixed solvent thereof Phosphorus lithium, lithium boron tetrafluoride, lithium hexaantimony, lithium arsenic hexafluoride, Lithium chlorate, lithium _{trifluoromethanesulfonate, Li (CF 3 SO 2)} 2 N, LiC 4 F 9 SO 3, LiSbF 6, LiAlO 4, LiAlCl 4, LiN (C x F 2x + 1 SO 2) (C y F 2y + 1 It is possible to use one of the electrolytes consisting of lithium salts such as Li 2 and LiI, or a mixture of two or more of them dissolved in SO ₂ ) (where x and y are natural numbers), LiCl, and LiI.

  Also, various other non-aqueous electrolytes and solid electrolytes can be used. For example, various ionic liquids to which lithium ions are added, a pseudo-solid electrolyte in which an ionic liquid and a fine powder are mixed, a lithium ion conductive solid electrolyte, and the like can be used.

  Furthermore, for the purpose of improving charge and discharge cycle characteristics, the above-mentioned electrolytic solution can be appropriately made to contain a compound that promotes stable film formation on the surface of the negative electrode active material. For example, vinylene carbonate (VC), fluorobenzene, cyclic fluorinated carbonate (fluoroethylene carbonate (FEC), trifluoropropylene carbonate (TFPC), etc.), or chain fluorinated carbonate (trifluorodimethyl carbonate (TFDMC), Fluorinated carbonates such as trifluorodiethyl carbonate (TFDEC), trifluoroethyl methyl carbonate (TFE MC), etc.] are effective. In addition, the said cyclic fluorinated carbonate and chain | strand-shaped fluorinated carbonate can also be used as a solvent like ethylene carbonate.

  A separator is disposed between the positive electrode plate and the negative electrode plate as described above to form a battery structure. The battery structure is wound or folded and placed in a cylindrical battery case or a rectangular battery case, and then an electrolyte is injected to complete a lithium ion battery.

  In addition, after the battery structure is stacked in a bicell structure, the battery structure is impregnated with an organic electrolytic solution, and the obtained product is put in a pouch and sealed to complete a lithium ion polymer battery.

Among the silicon oxide structures according to the present invention, in contrast to the conventional general atomic composition of silicon oxide, as shown in FIG. 3, in the spectrum measured by infrared spectroscopy (IR), 820~920cm ratio of ^-1 intensity of peak 1 derived from Si-H bonds in the _{(I 1)} and the intensity of peak 2 from the Si-O-Si bond in 1000 to 1200 ^-1 _{(I 2)} ( The general formula SiO _x2 H _y2 (0.3 <x2 <1.5, as I ₁ / I ₂ ) is in the range of 0.01 to 0.35 and can be derived from the elemental analysis values in Table 1 And those having an atomic composition represented by 0.01 <y2 <0.35) are particularly preferable. A secondary battery (for example, a lithium ion secondary battery, a lithium ion polymer secondary battery) using a silicon oxide structure specified by these parameters secures particularly high battery capacity and good initial charge and discharge. Such secondary battery embodiments are particularly preferred because they exhibit efficiency and cycling characteristics.

Furthermore, among the silicon oxide structures according to the present invention, in the spectrum measured by infrared spectroscopy, of the peaks derived from the Si-O-Si bond, the intensity of the peak 2-1 near 1170 cm ⁻¹ (I It is particularly preferable that the ratio (I _2-1 / I _2-2 ) of the intensity (I _2-2 ) of the peak 2-2 in the vicinity of _2-1 ) and 1070 cm ^-1 is more than 1. A secondary battery (for example, a lithium ion secondary battery, a lithium ion polymer secondary battery) using a silicon oxide structure specified by the range of the peak ratio also secures particularly high battery capacity and has a good initial stage. Such secondary battery embodiments are particularly preferred because they exhibit charge and discharge efficiency and cycle characteristics. In addition, the characteristics of the peak ratio of the said baked product are the same about the silicon type nanoparticle containing hydrogen polysilsesquioxane which is a precursor. That is, since the bond between the silicon-based nanoparticles and the silicon oxide structure is maintained even when the heat treatment is performed, the silicon-based nanoparticle-containing hydrogen polysilsesquioxane having the above peak ratio remains I ₂ even after the heat treatment. The state of ₋₁ / I _2-2 > 1 is also maintained.

  In such a silicon-based nanoparticle-containing hydrogen polysilsesquioxane fired product, the silicon-based nanoparticles chemically and strongly react with each other through the silicon oxide structure derived from the hydrogen polysilsesquioxane before heat treatment. It is bonded (for example, Si-O-Si bond). As a result, silicon-based nanoparticles of primary particles form a network structure, and a secondary aggregate in which primary particles are collected is formed.

In the above network structure, the portion of the silicon oxide structure (ie, the skeleton connecting the silicon nanoparticles) excluding the silicon nanoparticles plays a role of a buffer layer for expansion and contraction of the silicon nanoparticles, and as a result, charge and discharge It is inferred that the miniaturization of silicon-based nanoparticles generated at the time of repetition of is suppressed.
And in the present invention, the 50% cumulative mass particle size distribution diameter D50 in the particle size distribution in the above-mentioned oxide structure is controlled to be less than 3.0 μm, so higher levels can be obtained as shown in the following examples. It is possible to secure the capacity maintenance rate of

  In addition, the said structure described about "silicon | silicone-type nanoparticle containing hydrogen polysilsesquioxane baking material" is not limited only to the concept of "silicon | silicone-type nanoparticle containing hydrogen polysilsesquioxane baking material", It should be noted that it can be widely adopted in the broader term "silicon oxide structure" unless there is a particular contradiction. That is, those “silicon oxide structure” embodiments are also substantially as described herein.

  EXAMPLES The present invention will be more specifically described by way of reference examples, examples and comparative examples, but the present invention is not limited to the examples.

Various analyzes and evaluations were performed on some of the samples prepared in the reference examples, examples, and comparative examples.
The measurement devices / methods of “infrared spectroscopy measurement”, “elemental analysis measurement” and “particle size distribution measurement” and “evaluation of battery characteristics” in each reference example, example and comparative example are as follows: .

(Infrared spectroscopy measurement)
Infrared spectroscopy measurement is transmission measurement by KBr method using a Nicolet iS5 FT-IR manufactured by Thermo Fisher Scientific as an infrared spectrometer (resolution 4 cm ⁻¹ , scanning number 16 times, data interval 1.928 cm ⁻¹ , In a detector DTGS KBr), the intensity (I ₂ ) of peak 2 derived from the Si—O—Si bond at 1000 to 1200 cm ⁻¹ was measured. Each peak intensity was obtained by connecting the start point and the end point of the target peak with a straight line, partially performing baseline correction, and then measuring the height from the baseline to the peak top. Peak derived from the bond of Si-O-Si, in order to exist in two places, the intensity of the peak around ^-1 peak position 1170cm perform peak separation _I 2-1, the intensity of the peak around 1070 cm ^-1 I _2-2 and the high-intensity peak intensities of the two peaks was defined as I _2.

(Elemental analysis)
For elemental composition analysis, solidify the sample powder into a pellet, irradiate the sample with He ions accelerated to 2.3 MeV, and analyze the energy spectrum of the backscattered particles and the energy spectrum of the forward-scattered hydrogen atoms. This is done by the RBS (Rutherford Backscattering Analysis) / HFS (Hydrogen Forward Scattering Analysis) method, which gives highly accurate composition values including hydrogen. The measurement apparatus used is Pelletron 3SDH manufactured by National Electrostatics Corporation, and incident ions: 2.3 MeV He, RBS / HFS simultaneous measurement incident angle: 75 deg. , Scattering angle: 160 deg. Sample current: 4 nA, and beam diameter: 2 mmφ.

(Measurement of particle size distribution)
In the following Examples 1 and 2 and Comparative Examples 4 to 8, the particle size distribution of the prepared silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (10) to (16) is measured, and in particular, 50% in the particle size distribution The cumulative mass particle diameter distribution diameter D50 was calculated. The measurement method of particle size distribution is as follows. Take a small amount of the prepared silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product in a beaker, add a few drops of water and 0.5% triton X-100 aqueous solution, and use ultrasonic homogenizer US-150 manufactured by Nippon Seiki Co., Ltd. Dispersion treatment was carried out for 3 minutes to prepare a measurement sample. The measurement sample was measured using a laser diffraction scattering particle size distribution measuring apparatus MT3300II manufactured by Microtrack Bell Inc.

(Observation by scanning electron microscope)
It measured at arbitrary acceleration voltages using Keyence Corporation VE-9800 or Hitachi High-Technologies Corporation SU-90.

(Evaluation of battery characteristics)
A lithium ion battery was produced using the negative electrode active material containing the sample of a predetermined example or a comparative example, and the charge / discharge characteristic of the battery was measured as follows.
Using BTS 2005 W manufactured by Nagano, constant current charge is performed at a current of 100 mA per gram of silicon nanoparticles containing hydrogen polysilsesquioxane until it reaches 0.001 V with respect to the Li electrode, and then 0.001 V While maintaining the voltage, constant voltage charging was performed until the current reached a current value of 20 mA or less per 1 g of the active material.
The charged cells were subjected to a constant current discharge at a current of 100 mA per 1 g of the active material until a voltage of 1.5 V was reached after a rest period of about 30 minutes.
In addition, the charge capacity is calculated from the integrated current value until the constant voltage charge ends, and the discharge capacity is calculated from the integrated current value until the battery voltage reaches 1.5 V, and the first discharge capacity is the first charge The value obtained by dividing the value by volume and expressing it in percentage is regarded as the initial charge and discharge efficiency. At the time of switching of each charge and discharge, the circuit was paused for 30 minutes.

The same conditions were used for charge and discharge cycle characteristics.
In addition, charge / discharge efficiency was made into the ratio of discharge capacity with respect to charge capacity of the first time (1st cycle of charge / discharge). The capacity retention rate is the ratio of the discharge capacity in the 50th cycle of charge and discharge to the discharge capacity of the first time for Reference Examples 2 to 12 and Comparative Examples 1 to 5, and Examples 1 and 2 and Comparative Examples 4 to 4 The ratio of the discharge capacity in the 100th cycle of charge and discharge to the discharge capacity of the first time was taken as the value of 8.

[Reference Example 1]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Powder (1))
In a 50 ml beaker, 20 g of pure water and 1.92 g of silicon nanopowder (Sigma Aldrich, less than 100 nm (however, 10 nm exceeds)) were added, and a silicon nanoparticle dispersed aqueous solution was prepared with an ultrasonic cleaner. . This silicon fine particle dispersion, 2.43 g (24 mmol) of 36% by weight hydrochloric acid and 218.6 g of pure water are charged in a 500 ml three-necked flask, and stirred at room temperature for 10 minutes to disperse the silicon nanoparticles throughout. Then, 45 g (274 mmol) of triethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise at 25 ° C. while stirring. After completion of the dropwise addition, the hydrolysis reaction and the condensation reaction were carried out for 2 hours at 25 ° C. while stirring.
After the reaction time, the reaction product was filtered through a membrane filter (pore diameter 0.45 μm, hydrophilic) to recover a solid. The obtained solid was dried under reduced pressure at 80 ° C. for 10 hours to obtain 16.4 g of silicon nanoparticles-containing hydrogen polysilsesquioxane powder (1) (Reference Example 1).

[Reference Example 2]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (1))
After placing 10.0 g of the silicon nanoparticle-containing hydrogen polysilsesquioxane powder (1) of Reference Example 1 on an SSA-S grade alumina boat, the boat is placed in a vacuum purge type tube furnace KTF43N1-VPS The heat treatment conditions are set at a rate of 4 ° C./minute while supplying argon gas at a flow rate of 250 ml / minute under an argon gas atmosphere (high purity argon gas 99.999%). By heating and baking at 900 ° C. for 1 hour, a baked product of silicon nanoparticle-containing hydrogen polysilsesquioxane was obtained.
Subsequently, the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product is crushed and ground for 5 minutes in a mortar, and classified using a stainless steel sieve having an opening of 32 μm, and thus the maximum particle diameter is 32 μm. 9.58 g of nanoparticles-containing hydrogen polysilsesquioxane calcined product (1) was obtained.

(Fabrication of negative electrode)
In 20 g of a 2% by weight aqueous solution of carboxymethyl cellulose, 3.2 g of the silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (1) and 0.4 g of acetylene black manufactured by Denka Co., Ltd. were added, and a stirrer was used in the flask. After mixing for 15 minutes using it, distilled water was added so that solid content concentration might be 15 weight%, and it stirred for further 15 minutes, and prepared the slurry-like composition. This slurry-like composition was transferred to a thin-film spinning high-speed mixer (Filmix 40-40 type) manufactured by Plymix Co., and stirred and dispersed at a rotation number of 20 m / s for 30 seconds. The slurry after the dispersion treatment was coated on a copper foil roll at a thickness of 200 μm by a doctor blade method.
After coating, it was dried on an 80 ° C. hot plate for 90 minutes. After drying, the negative electrode sheet was pressed with a 2 t small precision roll press (manufactured by Sunk Metal Co., Ltd.). After pressing, the electrode was punched out with a φ14.50 mm electrode punching punch HSNG-EP, and dried under reduced pressure at 80 ° C. for 16 hours in a glass tube oven GTO-200 (SIBATA) to produce a negative electrode.

(Preparation and evaluation of lithium ion battery)
A 2032 type coin battery having a structure shown in FIG. 7 was produced. Ethylene carbonate and diethyl carbonate in which LiPF 6 is dissolved at a ratio of 1 mol / L as the electrolyte using the above negative electrode body as the negative electrode 1, metal lithium as the counter electrode 3, and a microporous polypropylene film as the separator 2 (Volume ratio) What added 5 weight% of fluoro ethylene carbonate to mixed solvent was used.
Subsequently, evaluation of the battery characteristic of a lithium ion battery was implemented by the method as stated above.

[Reference Example 3]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Powder (2))
200 g of pure water and 19.2 g of silicon nanopowder (Sigma Aldrich, less than 100 nm (volume based average particle size but more than 10 nm)) are placed in a 500 ml beaker, and a silicon nanoparticle dispersed aqueous solution is prepared with an ultrasonic cleaner. did. In a 3 l separable flask, this silicon nanoparticle dispersion, 12.2 g (120 mmol) of 36 wt% hydrochloric acid and 0.94 kg of pure water are stirred at room temperature for 10 minutes to disperse the entire silicon nanoparticles and stir Below, 167 g (1.37 mol) of trimethoxysilane (made by Tokyo Chemical Industry Co., Ltd.) was dripped at 25 degreeC. After completion of the dropwise addition, the hydrolysis reaction and the condensation reaction were carried out for 2 hours at 25 ° C. while stirring.
After the reaction time, the reaction product was filtered through a membrane filter (pore diameter 0.45 μm, hydrophilic) to recover a solid. The obtained solid was dried under reduced pressure at 80 ° C. for 10 hours to obtain 95.2 g of silicon nanoparticle-containing hydrogen polysilsesquioxane powder (2) (Reference Example 3).

[Reference Example 4]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (2))
Using the silicon nanoparticle-containing hydrogen polysilsesquioxane powder (2) of Reference Example 3, a silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (2) was prepared in the same manner as in Reference Example 2. .

(Production of negative electrode, production and evaluation of lithium ion battery)
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (2), the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (1) of Reference Example 2 is used in the same manner as in A negative electrode body was produced, and the battery characteristics of a lithium ion battery provided with it were evaluated.

[Reference Example 5]
(Preparation of silicon nanoparticles containing hydrogen polysilsesquioxane powder (3))
In preparation of silicon nanoparticles containing hydrogen polysilsesquioxane, silicon nanopowder (Sigma Aldrich, less than 100 nm (volume based average particle size, but more than 10 nm)) loading amount was changed to 77.0 g except The preparation was carried out in the same manner as in Reference Example 3 to obtain 153 g of silicon nanoparticle-containing hydrogen polysilsesquioxane powder (3) (Reference Example 5).
The infrared spectrum of the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (3) (Reference Example 5) is shown in FIG. 1, and the SEM photograph is shown in FIG.

[Reference Example 6]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (3))
Using the silicon nanoparticle-containing hydrogen polysilsesquioxane powder (3) of Reference Example 5, a silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (3) was prepared in the same manner as in Reference Example 2. .

(Production of negative electrode, production and evaluation of lithium ion battery)
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (3), the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (1) of Reference Example 2 is used similarly to the negative electrode. Preparation was performed, and the battery characteristic of the lithium ion battery provided with it was evaluated.

[Reference Example 7]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Powder (4))
In the preparation of silicon nanoparticles containing hydrogen polysilsesquioxane, 7.2 g (120 mmol) of acetic acid (Wako special grade reagent) was used instead of 12.2 g (120 mmol) of 36 wt% hydrochloric acid as a condensation catalyst. The preparation was carried out in the same manner as in Reference Example 5 to obtain 95.4 g of silicon nanoparticle-containing hydrogen polysilsesquioxane powder (4) (Reference Example 7).

[Reference Example 8]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (4))
A silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (4) was prepared in the same manner as in Reference Example 2 using the silicon nanoparticle-containing hydrogen polysilsesquioxane powder (4) of Reference Example 4 .

(Production of negative electrode, production and evaluation of lithium ion battery)
A negative electrode body was prepared in the same manner as when using the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (1) of Reference Example 2 for the obtained silicon nanoparticle-containing calcined hydrogen polysilsesquioxane product (4). The battery characteristics of a lithium ion battery equipped with the same were evaluated.

[Reference Example 9]
(Preparation of silicon nanoparticles containing hydrogen polysilsesquioxane powder (5))
In a 100 ml beaker, 50 g of pure water and 6.63 g of silicon nanopowder (Sigma Aldrich, less than 100 nm (however, 10 nm exceeds)) were added, and a silicon nanoparticle dispersed aqueous solution was prepared with an ultrasonic cleaner. . The silicon nanoparticle dispersion and 46 g of pure water were charged in a 500 ml three-necked flask and stirred for 10 minutes, and then the inside of the flask was purged with nitrogen. Subsequently, 16.0 g (118 mmol) of trichlorosilane was added dropwise at 20 ° C. with stirring while ice-cooling the flask. After completion of the dropwise addition, the hydrolysis reaction and the condensation reaction were carried out for 2 hours at 20 ° C. while stirring.
After the reaction time had elapsed, the reaction product was filtered using a membrane filter (pore diameter 0.45 μm, hydrophilic) to recover a solid. The obtained solid was dried under reduced pressure at 80 ° C. for 10 hours to obtain 12.6 g of silicon nanoparticle-containing hydrogen polysilsesquioxane powder (5) (Reference Example 9).

[Reference Example 10]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (5))
A silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (5) was prepared in the same manner as in Reference Example 2 using the silicon nanoparticle-containing hydrogen polysilsesquioxane powder (5) of Reference Example 9 .

(Production of negative electrode, production and evaluation of lithium ion battery)
Similarly to the case of using the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (1) of Reference Example 2 using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (5), the negative electrode is obtained. The battery characteristics of a lithium ion battery prepared and provided with it were evaluated. The infrared spectrum of the obtained silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (5) (Reference Example 10) is shown in FIG. 3, and the SEM photograph is shown in FIG.

[Reference Example 11]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (6))
The same as Reference Example 2 except that 10.0 g of the silicon nanoparticles-containing hydrogen polysilsesquioxane powder (5) was used, and the supply gas was changed to an argon-hydrogen mixed gas (hydrogen gas concentration: 10% by volume). Thus, 9.83 g of silicon nanoparticles-containing calcined hydrogen polysilsesquioxane (6) was obtained.

(Production of negative electrode, production and evaluation of lithium ion battery)
The negative electrode body was prepared in the same manner as in the case of using the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (1) of Reference Example 2 with respect to the silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (6). The battery characteristics of the lithium ion secondary battery equipped with it were evaluated.

[Reference Example 12]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (7))
A baked product is prepared in the same manner as in Reference Example 2 except that 10.0 g of the above-mentioned hydrogen nanoparticle-containing hydrogen polysilsesquioxane powder (5) is used and the firing temperature is set to 800 ° C. There were obtained 9.81 g of hydrogen polysilsesquioxane calcined product (7).

(Production of negative electrode, production and evaluation of lithium ion battery)
The negative electrode body was prepared in the same manner as in the case of using the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (1) of Reference Example 2 with respect to the silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (7). The battery characteristics of the lithium ion secondary battery equipped with it were evaluated.

Comparative Example 1
(Preparation of silicon nanoparticle composite silicon oxide (1))
A commercially available silicon monoxide (under 325 mesh manufactured by Aldrich) was classified using a 20 μm stainless steel sieve to obtain a silicon monoxide powder having a maximum particle diameter of 20 μm. In a planetary ball mill, using 10.0 g of the silicon monoxide of 20 μm or less and 6.37 g of silicon nanopowder (Sigma Aldrich, volume-based average particle diameter <100 nm (less than 100 nm)) and a zirconia container and a zirconia ball The mixture was ball-milled and mixed for 10 minutes to obtain silicon nanoparticle mixed silicon oxide (1). The infrared spectrum of the obtained silicon nanoparticle mixed silicon oxide (1) is shown in FIG. 3 (shown as Comparative Example 1 in FIG. 3). Next, 5 g of a 2 wt% aqueous solution of carboxymethylcellulose is added to the silicon nanoparticle mixed silicon oxide (1), and ball milling is performed for 2 hours in a planetary ball mill using a zirconia container and a zirconia ball. It dried at 100 degreeC with a dryer for 8 hours, the water | moisture content was removed, and silicon nanoparticle composite silicon oxide (1) (comparative example 1) was obtained.

(Fabrication of negative electrode)
A negative electrode was produced in the same manner as in Reference Example 2 except that the silicon nanoparticle composite silicon oxide (1) of Comparative Example 1 was used.

(Preparation and evaluation of lithium ion battery)
When the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (1) of Reference Example 2 is used except that the negative electrode produced from the above silicon nanoparticle composite silicon oxide (1) is used as the negative electrode body In the same manner, a lithium ion battery was produced, and the battery characteristics provided with it were evaluated.

Comparative Example 2
(Preparation of Hydrogen Silsesquioxane Polymer (1))
In a 3 l separable flask, 12.2 g (120 mmol) of 36 wt% hydrochloric acid and 1.19 kg of pure water are charged, and 167 g (1.37 mol) of trimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) under stirring at 25 ° C. It dripped at. After completion of the dropwise addition, the hydrolysis reaction and the condensation reaction were carried out for 2 hours at 25 ° C. while stirring.
After the reaction time, the reaction product was filtered through a membrane filter (pore diameter 0.45 μm, hydrophilic) to recover a solid. The obtained solid was dried under reduced pressure at 80 ° C. for 10 hours to obtain 76.0 g of hydrogen silsesquioxane polymer (1) (comparative example 2).

Comparative Example 3
(Preparation of calcined product of hydrogen silsesquioxane polymer (1))
Using the hydrogen silsesquioxane polymer (1) of Comparative Example 2, a baked product of hydrogen silsesquioxane polymer (1) was prepared in the same manner as in Reference Example 2.

(Production of negative electrode, production and evaluation of lithium ion battery)
The obtained hydrogen silsesquioxane polymer fired product (1) was prepared as in the case of using the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (1) of Reference Example 2 to prepare a negative electrode, The battery characteristics of the provided lithium ion battery were evaluated.

[Reference Example 13]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (8))
The preparation of the fired product was performed in the same manner as in Reference Example 2 except that the firing temperature in the heat treatment was set to 1100 ° C., to obtain a silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (8).
The result of the infrared spectroscopy measurement of the obtained silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (8) (Reference Example 13) is shown in FIG.

(Preparation of negative electrode body)
The same operation as in the case of using the silicon nanoparticle-containing hydrogen polysilsesquioxane sintered product (1) of Reference Example 2 except that the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (8) is used, the negative electrode body Was produced.
(Preparation and evaluation of lithium ion secondary battery)
A lithium ion secondary battery is produced in the same manner as in Reference Example 1 except that the negative electrode body produced from the silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (8) is used as the negative electrode body, and the battery characteristics are evaluated.

[Reference Example 14]
(Preparation of Silicon Nanoparticle-Containing Hydrogen Polysilsesquioxane Calcined Product (9))
The preparation of the fired product was performed in the same manner as in Reference Example 2 except that the firing temperature in the heat treatment was set to 500 ° C., to obtain a silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (9).
The result of the infrared spectroscopy measurement of the obtained silicon nanoparticle-containing hydrogen-polysilsesquioxane calcined product (9) (Reference Example 14) is shown in FIG.

(Production of negative electrode body, production and evaluation of lithium ion battery)
Lithium was prepared in the same manner as when using the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (1) of Reference Example 2 except that the silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (9) was used. An ion secondary battery was produced and battery characteristics were evaluated.

[result]
According to the results of Reference Examples 1 to 14 and Comparative Examples 1 to 3 above, it has an appropriate amount of Si—H bonds and has a chemical bond between the surface of the silicon nanoparticle and the hydrogen polysilsesquioxane, And, silicon nanoparticles containing hydrogen polysilsesquioxane and calcined products thereof having a new structure were obtained. The negative electrode active materials for secondary batteries produced from these fired products have higher initial discharge capacities and 50th cycle discharge capacities than conventional carbon-based negative electrode active materials, and good initial charge and discharge. It had efficiency. In addition, these negative electrode active materials for secondary batteries have a high capacity retention rate with little decrease in capacity due to charge and discharge cycles.
Therefore, specific silicon nanoparticle-containing hydrogen polysilsesquioxane can be used as a negative electrode material of the latest battery which can sufficiently withstand practical use as a lithium ion battery negative electrode active material by performing predetermined heat treatment processing. It can be evaluated that it is a useful compound that can be

  On the other hand, as shown in Comparative Example 1, a negative electrode using a negative electrode active material made of silicon oxide having no chemical bond and no Si-H bond on the surface of silicon nanoparticles was employed. As for the battery characteristics, although the initial charge / discharge efficiency shows a certain degree of value compared with the negative electrode employing the negative electrode active material according to the above-mentioned reference example and the examples described later, a rapid capacity decrease is observed, and a lithium ion battery As did not reach a practical level.

Furthermore, the calcined product of hydrogen polysilsesquioxane not containing silicon nanoparticles according to Comparative Example 3 has a peak 2-170 ° C- ^{1 in} the infrared absorption spectrum among peaks derived from Si-O-Si bond. The ratio (I _2-1 / I _2-2 ) of the intensity (I _2-1 ) of ^{1 to} the intensity (I _2-2 ) of the peak 2-2 near 1070 cm ⁻¹ does not exceed 1 and each reference As seen in the fired product according to the example, it had a network structure due to a chemical bond between silicon nanoparticles and a silicon oxide structure derived from hydrogen polysilsesquioxane. Such a negative electrode using silicon oxide that does not have a chemical bond with the surface of silicon nanoparticles has a constant initial charge / discharge efficiency as compared with a negative electrode using the negative electrode active material obtained in the reference example or the example. Although showing a value of the degree, a rapid capacity reduction was seen and it did not reach a practical level as a lithium ion secondary battery

It is to be noted that the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product fired at a temperature exceeding 1000 ° C. shown in Reference Example 13 may be produced from this fired product, probably because it does not have an appropriate amount of Si—H bonds. The characteristics of the battery employing the negative electrode were good in cycle characteristics but relatively low in initial discharge capacity.
Furthermore, the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product of Reference Example 14 has excellent Si-H bonds, so the cycle characteristics are good as in Comparative Test Example 13, but the initial discharge capacity is It was low.

In Reference Examples 1 to 14, when a predetermined silicon compound is hydrolyzed and condensed in the presence of silicon nanoparticles, the pH of the reaction solution is not adjusted to the predetermined range of the present invention, and each silicon nanoparticle-containing hydrogen produced In the polysilsesquioxane fired product, it is considered that the 50% cumulative mass particle size distribution diameter D50 does not fall within the predetermined range of the present invention.
However, in Examples 1 and 2 shown below and Reference Examples 1 to 14, silicon nanoparticles are obtained by hydrolyzing and condensing a predetermined silicon compound (formula (1)) in the presence of silicon nanoparticles. It is common in the point which has obtained hydrogen polysilsesquioxane containing or those baking products. In other words, the difference between Examples 1 and 2 shown below and Reference Examples 1 to 14 is that in the Examples, the pH of the reaction solution is adjusted to a predetermined range when the predetermined silicon compound is hydrolyzed and condensed. While the aggregation of particles is suppressed to a certain extent, in Reference Examples 1 to 14, the control of silicon nanoparticle aggregation by such pH adjustment is not performed, and silicon nanoparticles containing hydrogen manufactured in both It can be seen that there is no essential difference in the chemical composition of polysilsesquioxane.

That is, in consideration of the fact that there is no essential difference between the chemical compositions of the two, it is understood that the results of Reference Examples 1 to 14 support the following. That is, among the several embodiments of the present invention, the embodiment relating to the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product specified by the general formula SiO _{x 2} H _{y 2} is specified by the general formula SiO _{x 1} H _{y 1} embodiment of a silicon nanoparticle containing hydrogen polysilsesquioxane, as well as from the the bond of Si-O-Si peak intensity 1 derived from Si-H bonds in the spectrum measured by infrared spectroscopy (I ₁₎ The embodiment according to the silicon nanoparticle-containing hydrogen polysilsesquioxane specified by the ratio (I ₁ / I ₂ ) to the intensity (I ₂ ) of peak 2 and the fired products thereof exhibit various battery characteristics in a well-balanced manner It can be derived that it is possible to exhibit a higher level of capacity maintenance rate.

  In the present invention, it is needless to say that specification by the above atomic composition or peak intensity by infrared spectroscopy is not necessarily essential, and it is essential that the 50% cumulative mass particle diameter distribution diameter D50 is in a predetermined range, Also in the above reference example, if pH is adjusted so that the 50% cumulative mass particle size distribution diameter D50 falls within the predetermined range, the capacity retention can be improved, considering the results of the examples shown below. Is easily predicted.

  Hereinafter, the predetermined pH range in the production method of the present invention, the particle size distribution (50% cumulative mass particle diameter distribution diameter D50) of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product produced, and the product The Example and comparative example which show the relationship with the battery characteristic of a battery are shown.

Example 1
In a 200-ml beaker, add 70 g of pure water and 11.2 g of silicon nanopowder (Sigma Aldrich, <100 nm (volume based average particle size but over 10 nm)), and prepare an aqueous solution of silicon nanoparticle dispersion with an ultrasonic cleaner. did. In a 500 ml separable flask, this silicon nanoparticle dispersion, 1.76 g (0.0174 mmol) of 36% by weight hydrochloric acid and 104 g of pure water are stirred at room temperature for 10 minutes to disperse the entire silicon nanoparticles and stir Below 32.9 g (200 mmol) of trimethoxysilane (made by Tokyo Chemical Industry Co., Ltd.) was dripped at 25 degreeC. After completion of the dropwise addition, the hydrolysis reaction and the condensation reaction were carried out for 2 hours at 25 ° C. while stirring.
In addition, when pH of the reaction solution after throwing in hydrochloric acid was measured, as shown in the following Table 3, pH was 4.

After the reaction time, the reaction product was filtered using a membrane filter (pore diameter 0.45 μm, hydrophilic) to recover a solid. The obtained solid was dried under reduced pressure at 80 ° C. for 10 hours to obtain 21.3 g of silicon nanoparticle-containing hydrogen polysilsesquioxane powder (10).
Furthermore, using the silicon nanoparticle-containing hydrogen polysilsesquioxane powder (10) obtained above, a silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (10) is prepared in the same manner as in Reference Example 2. Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced, and the battery characteristics were evaluated.
In addition, a scanning electron micrograph of the silicon nanoparticle-containing calcined hydrogen polysilsesquioxane (10) is shown in FIG. 5 [(a): 10,000 times, (b): 1,000 times].
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (10) was measured, it became clear that the calcined product has a particle size distribution as shown in FIG. In addition, the 50% cumulative mass particle size distribution diameter D50 was 1.746 μm as shown in Table 3.

Example 2
Similar to Example 1, except that 0.164 g (1.74 mmol) of acetic acid was used in place of 1.76 g (0.0174 mmol) of 36 wt% hydrochloric acid in Example 1, except that silicon nanoparticles containing hydrogen polysil A sesquioxane powder (11) was produced.
In addition, when pH of the reaction solution after throwing in acetic acid was measured, as shown in the following Table 3, pH was 3.38.
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (11), a silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (11) is prepared in the same manner as in Reference Example 2, Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced and the battery characteristics were evaluated.
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (11) was measured, the 50% cumulative mass particle diameter distribution diameter D50 was 1.683 μm as shown in Table 3.

Comparative Example 4
In the same manner as in Example 1 except that 17.6 g (174 mmol) of hydrochloric acid was used instead of 1.76 g (0.0174 mmol) of 36 wt% hydrochloric acid in Example 1, a silicon nanoparticle-containing hydrogen polysilsesquioxane was used. Sun powder (12) was produced.
In addition, when pH of the reaction solution after throwing in hydrochloric acid was measured, as shown in the following Table 3, pH was 0.
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (12), a silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (12) is prepared in the same manner as in Reference Example 2, Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced and the battery characteristics were evaluated.
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (12) was measured, the 50% cumulative mass particle diameter distribution diameter D50 was 3.194 μm as shown in Table 3.

Comparative Example 5
A silicon nanoparticle-containing hydrogen polysil was prepared in the same manner as in Example 1 except that 1.76 g (17.4 mmol) of hydrochloric acid was used instead of 1.76 g (0.0174 mmol) of 36 wt% hydrochloric acid in Example 1. A sesquioxane powder (13) was produced.
In addition, when pH of the reaction solution after throwing in hydrochloric acid was measured, as shown in the following Table 3, pH was 1.
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (13), a silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (13) is prepared in the same manner as in Reference Example 2, Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced and the battery characteristics were evaluated.
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (13) was measured, this calcined product has a particle size distribution as shown in FIG. Diameter distribution diameter D50 was 4.739 micrometers as shown in Table 3.

Comparative Example 6
A silicon nanoparticle-containing hydrogen polysilsesquioxane was prepared in the same manner as in Example 1 except that 176 mg (1.74 mmol) of hydrochloric acid was used instead of 1.76 g (0.0174 mmol) of 36 wt% hydrochloric acid in Example 1. Sun powder (14) was produced.
In addition, when pH of the reaction solution after throwing in hydrochloric acid was measured, as shown in the following Table 3, pH was 2.
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (14), a silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (14) is prepared in the same manner as in Reference Example 2, Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced and the battery characteristics were evaluated.
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (14) was measured, the 50% cumulative mass particle diameter distribution diameter D50 was 4.749 μm as shown in Table 3.

Comparative Example 7
A silicon nanoparticle-containing hydrogen polysil was prepared in the same manner as in Example 1 except that 17.6 mg (0.174 mmol) of hydrochloric acid was used instead of 1.76 g (0.0174 mmol) of 36 wt% hydrochloric acid in Example 1. A sesquioxane powder (15) was produced.
In addition, when pH of the reaction solution after throwing in hydrochloric acid was measured, as shown in the following Table 3, pH was 3.
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (15), a silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (15) is prepared in the same manner as in Reference Example 2, Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced and the battery characteristics were evaluated.
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (15) was measured, the 50% cumulative mass particle diameter distribution diameter D50 was 3.324 μm as shown in Table 3.

Comparative Example 8
In the same manner as in Example 1 except that 10.4 g (174 mmol) of acetic acid was used instead of 1.76 g (0.0174 mmol) of 36 wt% hydrochloric acid in Example 1, a silicon nanoparticle-containing hydrogen polysilsesquioxane was used. Sun powder (16) was produced.
In addition, when pH of the reaction solution after throwing in hydrochloric acid was measured, as shown in the following Table 3, pH was 2.38.
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (16), a silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (16) is prepared in the same manner as in Reference Example 2, Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced and the battery characteristics were evaluated.
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (16) was measured, the 50% cumulative mass particle diameter distribution diameter D50 was 5.244 μm as shown in Table 3.

Comparative Example 9
A silicon nanoparticle-containing hydrogen polysil was prepared in the same manner as in Example 1 except that 1.04 g (17.4 mmol) of acetic acid was used instead of 1.76 g (0.0174 mmol) of 36% by weight hydrochloric acid in Example 1. A sesquioxane powder (17) was produced.
In addition, when pH of the reaction solution after throwing in hydrochloric acid was measured, as shown in the following Table 3, pH was 2.88.
Using the obtained silicon nanoparticle-containing hydrogen polysilsesquioxane powder (17), a silicon nanoparticle-containing hydrogen polysilsesquioxane calcined product (17) is prepared in the same manner as in Reference Example 2, Furthermore, a lithium ion battery using the negative electrode and the same negative electrode was produced and the battery characteristics were evaluated.
Furthermore, when the particle size distribution of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (17) was measured, the 50% cumulative mass particle size distribution diameter D50 was 3.022 μm as shown in Table 3.

  In Table 3 below, the values of the reaction solution pH when hydrolyzing and condensing various silicon compounds for Examples 1 and 2 and Comparative Examples 4 to 8, the obtained silicon nanoparticles containing hydrogen polysilsesquioxane are obtained. The value of 50% accumulation mass particle diameter distribution diameter D50 of sun baking products (10)-(17), and the measurement result and evaluation result of a battery characteristic are shown.

[result]
As shown in Table 3, in Examples 1 and 2 in which the pH of the reaction solution was adjusted to a relatively high weakly acidic region in the reaction of hydrolyzing and condensing a predetermined silicon compound in the presence of silicon nanoparticles, The 50% cumulative mass particle size distribution diameter D50 of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired product (10) and (11) is 1.746 μm and 1.683 μm, respectively, and the particle size is significantly reduced. In particular, the particle size distribution of Example 1 and the particle size distribution of Comparative Example 5 are shown in the graph of FIG. As shown in FIG. 6, the particle size peak of Example 1 is shifted to the left in the horizontal direction with respect to the particle size peak of Comparative Example 5, and it can be seen that the particle size is smaller than Comparative Example 5.
In addition, the silicon oxide structures obtained in Reference Examples 5 and 10 in which the pH is not controlled / monitored show remarkable aggregation or aggregation of primary particles as observed in the electron micrographs of FIGS. 2 and 4 respectively. It can be seen that the particle size of the secondary assembly is relatively large. On the other hand, in the silicon oxide structure obtained in Example 1 in which the pH was controlled to a predetermined range, aggregation or aggregation of primary particles was suppressed as observed in the electron micrograph of FIG. The particle size of the secondary assembly is small and has a fine network structure.
In Comparative Examples 4 to 9, the pH of the reaction solution is adjusted so as to deviate from the predetermined range of the present invention, and specifically, it is adjusted to the strongly acidic region or in the vicinity thereof. As a result, the 50% cumulative mass particle diameter distribution diameter D50 of the silicon nanoparticle-containing hydrogen polysilsesquioxane fired products (12) to (17) manufactured each had a large value exceeding 3.0 μm (Table 3 and Comparative Example 5 in FIG.

  As to the reason why the difference in 50% cumulative mass particle size distribution diameter D50 between Example 1 and 2 and Comparative Examples 4 to 9 occurred, in Examples 1 and 2, the pH of the reaction solution was relatively acidic. The absolute value of the zeta potential on the surface of the silicon nanoparticles is increased, the aggregation of the silicon nanoparticles is suppressed to a certain extent, and secondary aggregates formed by the aggregation of the silicon nanoparticles are adjusted. It is presumed that this is due to the decrease in average particle size. In other words, in Comparative Examples 4 to 9, since the pH of the reaction solution was adjusted to a region with high acidity, the absolute value of the zeta potential on the surface of the silicon nanoparticle becomes small, and aggregation of silicon nanoparticles is promoted. As a result, it is considered that this is attributed to the increase in the average particle size of secondary aggregates formed by the aggregation of silicon nanoparticles.

And when it sees about the result of battery evaluation, the capacity retention rate after cycle test (100 cycles) has a value of more than 84% about Examples 1 and 2 where 50% cumulative mass particle diameter distribution diameter D50 is small as mentioned above. The batteries produced in these examples exhibited high capacity retention rates.
On the other hand, in the batteries manufactured in Comparative Examples 4 to 9 in which the 50% cumulative mass particle size distribution diameter D50 is large, the capacity retention after 100 cycles was less than 84%, which is a lower value than in the example. .

  As described above, when the pH of the reaction solution is adjusted to the predetermined range of the present invention when hydrolyzing and condensing a predetermined silicon compound in the presence of silicon nanoparticles, the hydrolysis and condensation proceed at a suitable time, The aggregation of the silicon nanoparticles is moderately suppressed, and the average particle size of the entire sintered product (50% accumulation) with respect to the silicon nanoparticles containing hydrogen polysilsesquioxane produced and the secondary aggregation of silicon nanoparticles in the calcined product It has been shown that the mass particle size distribution diameter D50) is controlled to a suitable range. Furthermore, the silicon nanoparticles containing hydrogen polysilsesquioxane whose average particle size (50% cumulative mass particle size distribution diameter D50) is controlled in a suitable range as described above and the inventive product of the present invention manufactured using the calcined product thereof It has been shown that the negative electrode to secondary battery or secondary battery can exhibit high battery characteristics.

  The present invention is applicable as a negative electrode active material of a secondary battery, a negative electrode, and a secondary battery. Therefore, the present invention has high industrial applicability in the field of chemistry that manufactures negative electrode materials, in the field of electric and electronics such as secondary batteries and various electronic devices, and in the field of vehicles such as hybrid vehicles.

1: Anode material 2: Separator 3: Lithium counter electrode

Claims (28)

A silicon oxide skeleton containing Si and O in atomic composition,
Silicon-based nanoparticles chemically bonded to the silicon oxide skeleton;
Contains as a component,
50% cumulative mass particle size distribution diameter D50 in the particle size distribution is less than 3.0 μm,
Silicon oxide structure.   The silicon oxide structure according to claim 1, wherein a secondary aggregate in which the silicon-based nanoparticles are collected as primary particles is formed.   The silicon oxide structure according to claim 1 or 2, which has a Si-H bond. The silicon oxide structure according to any one of claims 1 to 3, which has an atomic composition represented by the general formula SiO _{x 2} H _{y 2} (0.01 <x2 <2, 0 <y2 <0.35). . The atomic composition represented by the general formula SiO _{x 2} H _{y 2} (0.3 <x2 <1.5, 0.01 <y2 <0.35) and having a Si-H bond. The silicon oxide structure according to any one of the above. The silicon oxide structure according to any one of claims 1 to 5, which is essentially free of carbon. The silicon oxide structure according to any one of claims 1 to 6, wherein the volume-based average particle diameter of the silicon-based nanoparticle is 10 nm to 500 nm. The silicon oxide structure according to any one of claims 1 to 7, which contains 5 to 65% by mass of the silicon-based nanoparticle. In the spectrum measured by infrared spectroscopy, a peak derived from Si-O-Si bond in 1000 to 1200 ^-1 and the intensity of peak 1 _{(I 1)} derived from Si-H bonds in 820～920Cm ^-1 the ratio of the second intensity _{(I 2) (I 1 /} I 2) is in the range of 0.01 to 0.35, silicon oxide structure according to any one of claims 1-8. In the spectrum measured by infrared spectroscopy, Si-O-Si of the peak derived from a binding, 1170Cm strength (peak 2-1) in the vicinity of ^-1 _{(I 2-1)} and 1070 cm ^-1 near the peak ( the ratio of the intensity _{(I 2-2)} peak _{2-2) (I 2-1 / I 2-2} ) is greater than 1, the silicon oxide structure according to any one of claims 1-9. The silicon oxide structure according to any one of claims 1 to 10, wherein the 50% cumulative mass particle size distribution diameter D50 is 2.0 μm or less. The negative electrode active material for secondary batteries containing the silicon oxide structure in any one of Claims 1-11. A negative electrode for a secondary battery, comprising the negative electrode active material for a secondary battery according to claim 12. The secondary battery provided with the negative electrode for secondary batteries of Claim 13. A method of producing a silicon oxide structure according to any one of claims 1 to 11, comprising the following steps (A) and (B):
(A) Hydrolysis and condensation reaction of a silicon compound represented by the following general formula (1) under the conditions of pH 2.95 or higher and in the presence of silicon-based nanoparticles, silicon-based nanoparticles containing hydrogen polysilsesquioxane To generate
HSi (R) ₃ (1)
(Wherein R represents identical or different, respectively, halogen, hydrogen, substituted or unsubstituted alkoxy having 1 to 10 carbons, substituted or unsubstituted aryloxy having 6 to 20 carbons, and 7 to 30 carbons) It is a group selected from substituted or unsubstituted arylalkoxy, provided that substituted or unsubstituted alkoxy having 1 to 10 carbon atoms, substituted or unsubstituted aryloxy having 6 to 20 carbon atoms, and 7 to 30 carbon atoms In the substituted or unsubstituted arylalkoxy of the above, any hydrogen may be substituted with a halogen); and (B) the silicon oxidation by firing the silicon-based nanoparticle-containing hydrogen polysilsesquioxane. Get the object structure. The method according to claim 15, wherein in the step (A), the hydrolysis and condensation reaction of the silicon compound is performed under the condition of pH 3.0 to 7.0. In the step (A), the silicon compound is added to a dispersion of silicon-based nanoparticles to which an acid is added so that the pH is 3.0 or more, and the hydrolysis and condensation reaction of the silicon compound is performed. Or the method according to 16. The method according to claim 17, wherein the acid is at least one selected from the group consisting of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. The method according to claim 17 or 18, wherein the acid is hydrochloric acid or acetic acid. The method according to any one of claims 15 to 19, wherein step (B) is performed under a non-oxidizing atmosphere and at a temperature of 600C to 900C. The method according to claim 21, wherein the non-oxidizing atmosphere is a hydrogen gas atmosphere or a mixed gas atmosphere of 2 vol% or more of hydrogen gas and an inert gas. The silicon-based nanoparticle-containing hydrogen polysilsesquioxane has an atomic composition represented by a general formula SiO _x1 H _y1 (0.25 <x1 <1.35, 0.16 <y1 <0.90), 22. A method according to any one of claims 15 to 21 having a chemical bond between the silicon based nanoparticle surface and hydrogen polysilsesquioxane. Method for producing silicon-based nanoparticle-containing hydrogen polysilsesquioxane, comprising the following step (A):
(A) Hydrolysis and condensation reaction of a silicon compound represented by the following general formula (1) under the conditions of pH 2.95 or higher and in the presence of silicon-based nanoparticles, silicon-based nanoparticles containing hydrogen polysilsesquioxane To generate
HSi (R) ₃ (1)
(Wherein R represents identical or different, respectively, halogen, hydrogen, substituted or unsubstituted alkoxy having 1 to 10 carbons, substituted or unsubstituted aryloxy having 6 to 20 carbons, and 7 to 30 carbons) It is a group selected from substituted or unsubstituted arylalkoxy, provided that substituted or unsubstituted alkoxy having 1 to 10 carbon atoms, substituted or unsubstituted aryloxy having 6 to 20 carbon atoms, and 7 to 30 carbon atoms In the substituted or unsubstituted arylalkoxy, any hydrogen may be substituted with halogen). The method according to claim 23, wherein, in the step (A), the hydrolysis and condensation reaction of the silicon compound is performed under the condition of pH 3.0 to 7.0. The silicon compound is added to a dispersion of silicon-based nanoparticles to which an acid has been added so that the pH is 3.0 or more in the step (A), and the hydrolysis and condensation reaction of the silicon compound is carried out. Or the method according to 24. The method according to claim 25, wherein the acid is at least one selected from the group consisting of formic acid, acetic acid, propionic acid, oxalic acid, citric acid, hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. 27. The method of claim 25 or 26, wherein the acid is hydrochloric acid or acetic acid. The silicon-based nanoparticle-containing hydrogen polysilsesquioxane has an atomic composition represented by a general formula SiO _x1 H _y1 (0.25 <x1 <1.35, 0.16 <y1 <0.90), 28. A method according to any one of claims 23 to 27, having a chemical bond between the silicon based nanoparticle surface and hydrogen polysilsesquioxane.