JP2015036450A - METHOD OF PRODUCING Ge-CONTAINING NANOPARTICLE AND Ge-CONTAINING NANOPARTICLE, AND BATTERY, INFRARED ABSORPTION MATERIAL, INFRARED PHOTODIODE, SOLAR BATTERY, LIGHT EMITTING ELEMENT AND ORGANISM RECOGNITION MATERIAL - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing Ge-containing nanoparticles in a process unlike the prior art and novel Ge-containing nanoparticles, and a battery, an infrared absorption material, an infrared photodiode, a solar battery, a light emitting element and an organism recognition material including the same.SOLUTION: A method of producing Ge-containing nanoparticles is to prepare nanoparticles at least comprising Ge, by reducing Ge oxide nanoparticles, with one element which has smaller Gibbs free energy ΔG relative to oxygen molecule (1 mol) than Gibbs free energy ΔG of Ge relative to oxygen molecule (1 mol) in an Ellingham diagram, and is selected from the group consisting of C, H, Zn, K, Na, Cr, Mn, V, Si, Ti, Al, Mg, Ca, Sc, Sr, Nb, Li, Ba, In, Y, Hf, Zr and Ta.

Description

  The present technology relates to a method for producing Ge-containing nanoparticles, Ge-containing nanoparticles, a battery, an infrared absorbing material, an infrared photodiode, a solar cell, a light emitting element, and a biorecognition material.

  In recent years, high capacity and rapid charge / discharge of lithium ion secondary batteries have been strongly demanded. The use of Si (silicon) or the like as a negative electrode active material has been studied for the purpose of obtaining a capacity higher than that of a carbon material. However, when Si or the like is used, there are currently problems with cycle characteristics and rapid charge / discharge.

  On the other hand, using Ge (for example, refer nonpatent literature 1) which is about 10,000 times as high as Si, and about 400 times as high lithium diffusibility as Si is considered as a material more effective than Si. .

J. Graetz, J. Electrochem. Soc. 2004, 151, A698

  An object of the present technology is to produce a Ge-containing nanoparticle having a different process from the conventional method and a novel Ge-containing nanoparticle, and a battery having the same, an infrared absorbing material, an infrared photodiode, a solar cell, a light-emitting element, and biological recognition To provide materials.

In order to solve the above-described problem, the present technology has a smaller Gibbs formation free energy ΔG for oxygen molecules (1 mol) than Gibbs formation free energy ΔG for Ge oxygen molecules (1 mol) in the Ellingham diagram, C, H _2, comprising Zn, K, Na, Cr, Mn, V, Si, Ti, Al, Mg, Ca, Sc, Sr, Nb, Li, Ba, in, Y, Hf, from at least one of Zr and Ta This is a method for producing Ge-containing nanoparticles in which Ge oxide nanoparticles are reduced with one element to prepare nanoparticles containing at least Ge.

In the present technology, a Ge-containing nanoparticle is prepared by reducing Ge halide with a reducing agent in a dry environment having a dew point of −30 ° C. or less to prepare the GeO _x (0.5 <x <1.5) nanoparticle. It is a manufacturing method.

The technology is Ge-containing nanoparticles comprising at least GeO _x (0.5 <x <1.5).

The present technology relates to an infrared absorbing material, an infrared absorbing material, an infrared photodiode element, a solar cell, a light emitting element, a living body, and having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5). It is a recognition material.

  According to the present technology, it is possible to provide a method for producing Ge-containing nanoparticles of a process different from the conventional process and novel Ge-containing nanoparticles.

FIG. 1 is a graph showing an Ellingham diagram. FIG. 2 is a cross-sectional view showing an example of a battery according to the third embodiment of the present technology. FIG. 3 is an enlarged cross-sectional view showing a part of the spirally wound electrode body 20 shown in FIG. FIG. 4A is an SEM image of PVP protected GeO ₂ nanoparticles. FIG. 4B is an SEM image of Ge / C nanocomposite particles. FIG. 5 is an optical photograph of Ge / C nanocomposite powder. FIG. 6A is an XRD pattern of PVP-protected GeO ₂ nanoparticles before reduction heat treatment and an XRD pattern of Ge / C nanocomposite particles after reduction heat treatment. FIG. 6B is a Raman spectrum of the PVP-protected GeO ₂ nanoparticles before the reduction heat treatment and a Raman spectrum of the Ge / C nanocomposite particles after the reduction heat treatment. FIG. 7A is an EDX spectrum of the Ge / C nanocomposite particles of Sample 1. FIG. 7B is a table showing the mass composition of Ge / C nanocomposite particles. FIG. 8 is an XPS spectrum of the Ge / C nanocomposite particles of Sample 1. FIG. 9A is a charge / discharge graph of the half-cell 1-1 and the half-cell 1-2. FIG. 9B is a graph in which the maintenance ratio is plotted against the number of cycles. FIG. 10A is an SEM image of PVP protected GeO nanoparticles. FIG. 10B is an SEM image of Ge / C nanocomposite particles. FIG. 11A shows Ge2p3 / 2 spectra obtained by XPS measurement of PVP-protected GeO nanoparticles before reduction heat treatment, Ge2p3 / 2 spectra obtained by XPS measurement of nanoparticles after 400 ° C. reduction heat treatment, and 600 ° C. reduction heat treatment. It is Ge2p3 / 2 spectrum obtained by XPS measurement of the nanoparticle of the latter. FIG. 11B shows an O1s spectrum obtained by XPS measurement of PVP-protected GeO nanoparticles before reduction heat treatment, an O1s spectrum obtained by XPS measurement of nanoparticles after 400 ° C. reduction heat treatment, and nanoparticles after 600 ° C. reduction heat treatment It is an O1s spectrum obtained by XPS measurement. FIG. 12 shows an XRD pattern of PVP-protected GeO nanoparticles before reduction heat treatment, an XRD pattern of nanoparticles after 400 ° C. reduction heat treatment, and an XRD pattern obtained by XPS measurement of nanoparticles after 600 ° C. reduction heat treatment. FIG. 13 is a charge / discharge graph of the half-cell 2-1 and the half-cell 2-3. FIG. 14 is a charge / discharge graph of the half-cell 2-2. 15A and 15B are SEM images of the Ge / C nanocomposite particles of Sample 3. FIG. FIG. 16 shows a Raman spectrum of PVP-protected GeO ₂ nanoparticles before the reduction heat treatment and a Raman spectrum of Ge / C nanocomposite particles after the reduction heat treatment.

Hereinafter, embodiments of the present technology will be described with reference to the drawings. The description will be given in the following order.
0. Technical background First Embodiment (First Example of Method for Producing Ge-Containing Nanoparticles)
2. Second Embodiment (Second Example of Method for Producing Ge-Containing Nanoparticles)
3. Third embodiment (application example)
4). Other Embodiment (Modification)
The embodiments described below are suitable specific examples of the present technology, and the contents of the present technology are not limited to these embodiments. Moreover, the effect described in this specification is an illustration to the last, is not limited, and does not deny that the effect different from the illustrated effect exists.

0. Technical background First, in order to facilitate understanding of the present technology, a technical background of the present technology will be described. For example, a Si (silicon) negative electrode forms a SiLi _x (x <4.4) compound by reaction with Li during charge / discharge, but has some fundamental difficulties in its formation process. . For example, (1) cycle characteristics are poor due to expansion and contraction, (2) Si and SiO have low conductivity, and (3) Li diffusion rate is slow compared to carbon materials.

  In contrast to (1), many efforts have been made to improve cycle characteristics by making nanoparticles (non-patent literature: Gohier et al., Adv. Mater., 2012, 24, 2592). This can be easily imagined from the relationship between the expansion rate (about 300%) and the strain displacement. It is known that stress cracking generally depends not on the expansion coefficient but on the amount of strain displacement (deviation induces dislocation). In other words, when a particle having a radius of 1 um expands by 300%, the radius becomes 1.443 um (displacement amount 443 nm), but in the case of a particle having a radius of 10 nm, the radius is about 14.43 nm (displacement amount 4.43 nm). Therefore, nano-particle formation has the effect of making it difficult for stress cracking to occur.

However, since nano-particle formation generally lowers conductivity, the problem (3) becomes more prominent. Therefore, Si nanoparticle negative electrode research is forced to be combined with highly conductive assistants such as graphene and carbon nanotubes (Non-patent literature: Lee et al., Chem Comm., 2010, 46, 2025; Gohier et al., Adv. Mater., 2012, 24, 2592). Furthermore, since the Si nanoparticles easily oxidize to SiO ₂ and become nano-sized, the oxidizing power increases, so that they have a pyrophoric property against moisture.

  In order to solve these problems, Ge (germanium) is effective. As described above, Ge has a high conductivity 10,000 times that of Si and 400 times higher lithium diffusibility, and is a material that can compensate for many of the defects of Si as a negative electrode. That is, Ge nanoparticles have a lower resistance than Si nanoparticles, and are a material excellent in high lithium diffusibility and nonflammability. Further, the Ge theoretical capacity (1600 mAh / g, 7366 Ah / L) has almost the same capacity per volume as compared with the Si theoretical capacity (4200 mAh / g, 8334 Ah / L).

In view of the above, the present technology provides a method for producing Ge-containing nanoparticles by a process different from the conventional method and novel Ge-containing nanoparticles. In at least one embodiment of the present technology, highly conductive nanoparticles can be realized. A battery using highly conductive nanoparticles can be rapidly charged and discharged because of its high conductivity. In a battery using highly conductive nanoparticles, cracks due to expansion and contraction can be prevented and cycle characteristics can be improved because of the nanoparticles.
Embodiments of the present technology will be described below.

1. First Embodiment (First Example of Method for Producing Ge-Containing Nanoparticles)
A method for producing Ge-containing nanoparticles according to the first embodiment of the present technology will be described. The first embodiment of the present technology provides a technique capable of easily synthesizing Ge-containing nanoparticles.

  In addition, in this specification, a nanoparticle means the microparticles | fine-particles whose primary particle diameter is nanosize. The nano-size typically means that the primary particle size is 1 nm or more and less than 1000 nm, and a size of several nm or more and several tens of nm. A material having a nano-sized size is referred to with a prefix “nano”, for example, a nanoparticle.

  Further, in this specification, the Ge-containing nanoparticle means a nanoparticle containing at least Ge (germanium), and is typically a single Ge nanoparticle or a nanoparticle containing Ge and another element. Say. Nanoparticles containing Ge and other elements are typically Ge oxide simple substance nanoparticles, composite nanoparticles of Ge and other elements (typically C, etc.) (nanocomposite particles), This refers to composite nanoparticles of Ge oxide and other elements (typically C).

The method for producing Ge-containing nanoparticles according to the first embodiment of the present technology includes, as a first step, ammonium hydroxide (NH ₄₎ in a solution in which a protective polymer and a Ge alkoxide are dissolved in an alcohol solvent in an air atmosphere. OH) and water (H ₂ O) are mixed, and a hydrolysis reaction is performed to prepare polymer-protected GeO ₂ nanoparticles whose surface is protected with a protective polymer.

In the method for producing Ge-containing nanoparticles according to the first embodiment of the present technology, after the first step, the polymer-protected GeO ₂ nanoparticles are converted into nitrogen (N ₂ ), argon (Ar ₂ ), In an atmosphere of hydrogen (H ₂ ) or a mixed gas thereof, reduction and heat treatment (reduction heat treatment) are performed to prepare Ge / C nanocomposite particles that are Ge-containing carbon material particles containing Ge and carbon (C). Process.

  In the second step, a reduction heat treatment according to the Ellingham diagram is performed. FIG. 1 shows an Ellingham diagram. The Ellingham diagram is a relationship diagram between Gibbs formation free energy (standard formation free energy of an oxide of each element, hereinafter sometimes referred to as ΔG) and temperature with respect to oxygen molecules (1 mol) of each element. The line t1 in FIG. 1 shows the change with respect to the temperature of ΔG with respect to oxygen molecules (1 mol) of carbon (C), and the line t2 shows the change with respect to the temperature of ΔG with respect to oxygen molecules (1 mol) of Ge.

According to the Ellingham diagram, the smaller the ΔG, the easier it is to oxidize. In the second step, according to the Ellingham diagram, GeO ₂ is reduced to Ge with an element having a smaller ΔG for oxygen molecules (1 mol) than ΔG for Ge oxygen molecules (1 mol).

Specifically, in the second step, according to the Ellingham diagram, GeO _{2 is changed} to Ge with carbon (C) having a smaller ΔG with respect to oxygen molecules (1 mol) than with ΔG with respect to oxygen molecules (1 mol) of germanium (Ge). Reduce. That is, in the second step, an oxidation-reduction reaction according to the Ellingham diagram occurs, and carbon (C) contained in the protective polymer reduces GeO ₂ to Ge. In addition, atmospheric gas (for example, hydrogen etc.) may act as a reducing agent for reducing Ge.

The temperature during the reduction heat treatment at which the reduction reaction (GeO ₂ → Ge) occurs is preferably such that ΔG with respect to oxygen molecules (1 mol) of Ge> ΔG with respect to oxygen molecules (1 mol) of carbon (C).

Specifically, for example, the temperature during the reduction heat treatment is preferably 700 ° C. or higher, and more preferably 800 ° C. or higher. When the temperature is lower than 700 ° C., the reduction reaction of GeO ₂ → Ge tends not to proceed. In addition, the temperature during the reduction heat treatment is more preferably 1000 ° C. or less from the viewpoint of suppressing aggregation and enlargement of Ge nanoparticles.

By performing the second step after the first step, Ge / C nanocomposite particles are obtained. This Ge / C nanocomposite particle is, for example, a Ge nanoparticle carrying a carbonized protective polymer. The particle diameter (primary particle diameter) of the nanocomposite particles is typically 500 nm or more and less than 1000 nm, for example. The particle diameter (primary particle diameter) of the polymer-protected GeO ₂ nanoparticles obtained in the first step is typically 50 nm or less, for example.

The Ge / C nanocomposite particles may have a peak in the vicinity of a binding energy of 29 eV and a peak in the vicinity of a binding energy of 34 eV in the Ge3d5 / 2 spectrum of XPS (X-ray Photoelectron Spectroscopy). Since this Ge / C nanocomposite particle contains reduced Ge derived from GeO ₂ , it is considered that oxygen is left behind in Ge. That is, it is presumed that the state is close to GeO. In recent years, it has been reported that SiO exhibits better cycle characteristics than Si, and it is considered that Ge / C nanocomposite particles derived from GeO ₂ tend to have high cycle characteristics.

  In the first step, Ge simple substance nanoparticles may be obtained instead of Ge / C nanocomposite particles by adjusting the amount of the protective polymer to be small.

In the first embodiment of the present technology, specifically, for example, Ge isopropoxide (Ge (O—iC ₃ H ₇ ) ₄ ) or the like is used as the Ge alkoxide used in the first step. it can. Note that a Ge-containing compound such as GeI ₄ may be used instead of Ge alkoxide.

  In the first embodiment of the present technology, an organic polymer compound having alcohol solubility can be used as the protective polymer used in the first step. Polyvinyl pyrrolidone (PVP), polyvinyl alcohol, etc. can be used as the organic polymer compound having alcohol solubility.

In the above-described method for producing Ge-containing nanoparticles, an example (GeO ₂ → Ge) in which Ge oxide is reduced with carbon (C) according to the Ellingham diagram has been described. However, according to the Ellingham diagram, carbon (C), Hydrogen (H ₂ ), zinc (Zn), potassium (K), sodium (Na), chromium (Cr), manganese (Mn), vanadium (V), silicon (Si), titanium (Ti), aluminum (Al) , Magnesium (Mg), calcium (Ca), scandium (Sc), strontium (Sr), niobium (Nb), lithium (Li), barium (Ba), indium (In), yttrium (Y), hafnium (Hf) Further, reduction may be performed with at least one of zirconium (Zr) and tantalum (Ta). In this case, according to the Ellingham diagram, the Ge oxide may be reduced with the above element having a smaller ΔG with respect to oxygen molecules (1 mol) than ΔG with respect to oxygen molecules (1 mol) of germanium (Ge). In this case, typically, for example, in the case of reduction with hydrogen (H ₂ ), for example, a hydrogen-containing gas (for example, pure hydrogen gas, a mixed gas of hydrogen and N ₂ and / or Ar, etc.) is used. , Ge oxide is reduced. When reducing with other elements, mix as a metal, or coat with a thin metal such as metal plating, or combine with carbon or hydrogen to reduce the metal oxide (oxide of the above metal element). The Ge oxide is further reduced with the reduced metal.

2. Second Embodiment (Second Example of Method for Producing Ge-Containing Nanoparticles)
A method for producing Ge-containing nanoparticles according to the second embodiment of the present technology will be described. The second embodiment of the present technology provides a technique capable of easily synthesizing Ge-containing nanoparticles. In addition, the second embodiment of the present technology provides a method for synthesizing a novel material (germanium monoxide (GeO) nanoparticles).

In the method for producing Ge-containing nanoparticles according to the second embodiment of the present technology, as a first step, oxygen such as air is used in a dry environment (typically an environment having a dew point of −30 ° C. or lower). In a containing atmosphere, a reducing agent is added at room temperature to a solution in which a protective polymer similar to the first embodiment and a halogenated Ge such as germanium chloride (GeCl ₄ ) are dissolved in an alcohol solvent, to thereby add polymer-protected GeO nanoparticles. Including the step of preparing.

In the first step, when Ge is reduced with a reducing agent, it is slightly oxidized in the atmosphere, so that the consumption reaction of GeCl ₄ is accelerated and GeO nanoparticles having a particle size of about 50 nm are synthesized.

As the reducing agent, for example, an alkali element-containing material, a hydrogen-containing material, an alkali element and a hydrogen-containing material can be used. Specifically, for example, NaBH ₄ or the like can be used as the reducing agent.

The polymer-protected GeO nanoparticles obtained in the first step comprise single phase GeO _x (0.5 <x <1.5) nanoparticles. For example, single-phase GeO _x (0.5 <x <1.5) nanoparticles are GeO _x (0.5 <x <1.5) in the Ge2p3 / 2 spectrum of XPS (X-ray Photoelectron Spectroscopy). This refers to nanoparticles that provide a single-phase spectrum. Single-phase GeO _x (0.5 <x <1.5) nanoparticles have a peak in the vicinity of a binding energy of 1218 eV in the XPS Ge2p3 / 2 spectrum. Single-phase GeO _x (0.5 <x <1.5) particles are amorphous.

For example, instead of under a dry environment, when the first step is performed under a normal atmospheric environment (an environment with moisture), GeO ₂ tends to be converted into moisture, so moisture is the main oxidant of Ge, It can be considered that the oxidizing power of oxygen with respect to Ge is small. For this reason, it is considered that GeO _{x (} 0.5 <x <1.5) nanoparticles different from GeO ₂ nanoparticles are generated in a dry environment.

In the present technology, after the first step, as a second step, the polymer-protected GeO nanoparticles are reduced under nitrogen (N ₂ ), argon (Ar ₂ ), hydrogen (H ₂ ), or a mixed gas atmosphere thereof. And a step of performing a heat treatment (reduction heat treatment) to prepare Ge / C nanocomposite particles.

In the second step, as in the first embodiment, according to the Ellingham diagram, GeO _x is reduced to Ge by an element having a smaller ΔG for oxygen molecules (1 mol) than ΔG for Ge oxygen molecules (1 mol). . Specifically, in the second step, as in the first embodiment, according to the Ellingham diagram, carbon (C) contained in the protective polymer as a reducing agent for reducing Ge is converted into the polymer-protected GeO nanocomposite. GeO _x is reduced to Ge. An atmosphere gas (for example, hydrogen) may also act as a reducing agent that reduces GeO _x .

The temperature during the reduction heat treatment in which the reduction reaction (GeO _x → Ge) occurs is preferably such that ΔG with respect to oxygen molecules (1 mol) of Ge> ΔG with respect to oxygen molecules (1 mol) of carbon (C).

Specifically, the temperature of the reduction heat treatment is preferably 600 ° C. or higher, for example. When the temperature is lower than 600 ° C., the reduction reaction of GeO _x → Ge tends not to proceed. In addition, the temperature of the reduction heat treatment is more preferably 1000 ° C. or less from the viewpoint of suppressing aggregation and enlargement of Ge nanoparticles.

  In the first step, Ge simple substance nanoparticles may be obtained instead of Ge / C nanocomposite particles by adjusting the amount of the protective polymer to be small.

In the second embodiment of the present technology, an example (GeO _x → Ge) in which Ge oxide is reduced with carbon (C) according to the Ellingham diagram has been described. However, according to the Ellingham diagram, carbon (C), Hydrogen (H ₂ ), zinc (Zn), potassium (K), sodium (Na), chromium (Cr), manganese (Mn), vanadium (V), silicon (Si), titanium (Ti), aluminum (Al) , Magnesium (Mg), calcium (Ca), scandium (Sc), strontium (Sr), niobium (Nb), lithium (Li), barium (Ba), indium (In), yttrium (Y), hafnium (Hf) Further, reduction may be performed with at least one of zirconium (Zr) and tantalum (Ta). In this case, according to the Ellingham diagram, Ge oxide can be reduced with the above element having a smaller ΔG with respect to oxygen molecules (1 mol) than ΔG with respect to oxygen molecules (1 mol) of germanium (Ge). In this case, typically, for example, in the case of reduction with hydrogen (H ₂ ), for example, a hydrogen-containing gas (for example, pure hydrogen gas, a mixed gas of hydrogen and N ₂ and / or Ar, etc.) is used. , Ge oxide is reduced. When reducing with other elements, mix as a metal, coat with a thin metal like metal plating, or combine with carbon or hydrogen to reduce the metal oxide (oxide of the above metal element) Then, the Ge oxide is further reduced with the reduced metal.

3. Third Embodiment A third embodiment of the present technology will be described. The third embodiment of the present technology is one application example or other application example of the Ge-containing nanoparticles of the present technology.

(One application example)
As one application example of the Ge-containing nanoparticles of the present technology, for example, a lithium ion secondary using at least one of the Ge-containing nanoparticles of the first embodiment and the second embodiment described above as a negative electrode Examples of the battery include batteries. Hereinafter, an example of the configuration of the battery will be described with reference to the drawings.

(Battery configuration)
The structure of the battery according to the third embodiment of the present technology will be described with reference to FIG. FIG. 2 is a cross-sectional view showing an example of a battery according to the third embodiment of the present technology. The battery according to the third embodiment of the present technology is, for example, a nonaqueous electrolyte battery, a nonaqueous electrolyte secondary battery that can be charged and discharged, and a lithium ion secondary battery, for example. . This battery is a so-called cylindrical type, and a strip-shaped positive electrode 21 and a negative electrode 22 together with a non-aqueous electrolyte, which is a liquid electrolyte (not shown), form a separator 23 in a substantially hollow cylindrical battery can 11. The wound electrode body 20 is wound around.

  The battery can 11 is made of, for example, iron plated with nickel, and has one end closed and the other end open. Inside the battery can 11, a pair of insulating plates 12 a and 12 b are respectively arranged perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 20.

  Examples of the material of the battery can 11 include iron (Fe), nickel (Ni), stainless steel (SUS), aluminum (Al), titanium (Ti), and the like. The battery can 11 may be plated with nickel or the like, for example, in order to prevent corrosion due to the electrochemical non-aqueous electrolyte accompanying charging / discharging of the battery. At the open end of the battery can 11, a battery lid 13 that is a positive electrode lead plate, and a safety valve mechanism and a thermal resistance element (PTC element: Positive Temperature Coefficient) 17 provided inside the battery lid 13 are insulated and sealed. It is attached by caulking through a gasket 18 for

  The battery lid 13 is made of, for example, the same material as that of the battery can 11 and has an opening for discharging gas generated inside the battery. In the safety valve mechanism, a safety valve 14, a disk holder 15, and a shut-off disk 16 are sequentially stacked. The protrusion 14 a of the safety valve 14 is connected to a positive electrode lead 25 led out from the wound electrode body 20 through a sub disk 19 disposed so as to cover a hole 16 a provided in the center of the shutoff disk 16. . By connecting the safety valve 14 and the positive electrode lead 25 via the sub disk 19, the positive electrode lead 25 is prevented from being drawn from the hole 16a when the safety valve 14 is reversed. Further, the safety valve mechanism is electrically connected to the battery lid 13 via the heat sensitive resistance element 17.

  In the safety valve mechanism, when the internal pressure of the battery becomes a certain level or more due to internal short circuit or heating from the outside of the battery, the safety valve 14 is reversed, and the electrical connection between the protruding portion 14a, the battery lid 13 and the wound electrode body 20 is achieved. Disconnects the connection. That is, when the safety valve 14 is reversed, the positive electrode lead 25 is pressed by the shut-off disk 16 and the connection between the safety valve 14 and the positive electrode lead 25 is released. The disc holder 15 is made of an insulating material, and when the safety valve 14 is reversed, the safety valve 14 and the shut-off disc 16 are insulated.

  Further, when further gas is generated inside the battery and the internal pressure of the battery further increases, a part of the safety valve 14 is broken and the gas can be discharged to the battery lid 13 side.

  In addition, for example, a plurality of vent holes (not shown) are provided around the hole 16a of the shut-off disk 16, and when gas is generated from the wound electrode body 20, the gas is effectively removed from the battery lid. It is set as the structure which can discharge | emit to 13 side.

  The resistance element 17 increases in resistance when the temperature rises, cuts off the current by disconnecting the electrical connection between the battery lid 13 and the wound electrode body 20, and generates abnormal heat due to an excessive current. To prevent. The gasket 18 is made of, for example, an insulating material, and the surface is coated with asphalt.

  The wound electrode body 20 accommodated in the battery is wound around the center pin 24. The wound electrode body 20 is formed by sequentially laminating a positive electrode 21 and a negative electrode 22 with a separator 23 interposed therebetween, and is wound in the longitudinal direction.

  A positive electrode lead 25 is connected to the positive electrode 21, and a negative electrode lead 26 is connected to the negative electrode 22. As described above, the positive electrode lead 25 is welded to the safety valve 14 and is electrically connected to the battery lid 13, and the negative electrode lead 26 is welded to and electrically connected to the battery can 11.

  FIG. 3 is an enlarged cross-sectional view showing a part of the spirally wound electrode body 20 shown in FIG. Hereinafter, the positive electrode 21, the negative electrode 22, and the separator 23 will be described in detail.

(Positive electrode)
The positive electrode 21 has, for example, a double-sided formation part in which a positive electrode active material layer 21B is provided on both surfaces of a positive electrode current collector 21A having one main surface and another main surface. Although not shown, the single-sided formation portion in which the positive electrode active material layer 21B is provided only on one side of the positive electrode current collector 21A may be provided. The positive electrode current collector 21A is made of, for example, a metal foil such as an aluminum foil.

  The positive electrode active material layer 21B contains one or more positive electrode materials capable of inserting and extracting lithium as a positive electrode active material. The positive electrode active material layer 21B may include other materials such as a binder and a conductive agent as necessary.

  As a positive electrode material capable of inserting and extracting lithium, for example, a lithium-containing compound is preferable. This is because a high energy density can be obtained. Examples of the lithium-containing compound include a composite oxide containing lithium and a transition metal element, and a phosphate compound containing lithium and a transition metal element. Especially, what contains at least 1 sort (s) of the group which consists of cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe) as a transition metal element is preferable. This is because a higher voltage can be obtained.

As the positive electrode material, for example, a lithium-containing compound represented by Li _x M1O ₂ or Li _y M2PO ₄ can be used. In the formula, M1 and M2 represent one or more transition metal elements. The values of x and y vary depending on the charge / discharge state of the battery, and are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10. Examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), and lithium nickel cobalt composite oxide (Li _x Ni). _1-z Co _z O ₂ (0 <z <1)), lithium nickel cobalt manganese composite oxide (Li _x Ni _(1-vw) Co _v Mn _w O ₂ (0 <v + w <1, v> 0, w > 0)), or lithium manganese composite oxide (LiMn ₂ O ₄ ) or lithium manganese nickel composite oxide (LiMn _2−t N _t O ₄ (0 <t <2)) having a spinel structure. . Among these, a complex oxide containing cobalt is preferable. This is because a high capacity can be obtained and excellent cycle characteristics can be obtained. Examples of the phosphate compound containing lithium and a transition metal element include a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (0 <u <1). ) And the like.

Specific examples of such a lithium composite oxide include lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), and lithium manganate (LiMn ₂ O ₄ ). A solid solution in which a part of the transition metal element is substituted with another element can also be used. Examples thereof include lithium nickel cobalt composite oxide (LiNi _0.5 Co _0.5 O ₂ , LiNi _0.8 Co _0.2 O ₂ etc.) and lithium nickel cobalt aluminum composite oxide (LiNi _0.80 Co _0.15 Al _0.05 O ₂ etc.). These lithium composite oxides can generate a high voltage and have an excellent energy density.

  Furthermore, from the viewpoint that higher electrode filling properties and cycle characteristics can be obtained, composite particles in which the surfaces of particles made of any of the above lithium-containing compounds are coated with fine particles made of any of the other lithium-containing compounds can be used. Good.

In addition, examples of positive electrode materials capable of inserting and extracting lithium include oxides such as vanadium oxide (V ₂ O ₅ ), titanium dioxide (TiO ₂ ), manganese dioxide (MnO ₂ ), and iron disulfide. (FeS ₂ ), disulfides such as titanium disulfide (TiS ₂ ) and molybdenum disulfide (MoS ₂ ), and chalcogenides containing no lithium such as niobium diselenide (NbSe ₂ ) (particularly layered compounds and spinel compounds) ), Lithium-containing compounds containing lithium, and conductive polymers such as sulfur, polyaniline, polythiophene, polyacetylene, or polypyrrole. Of course, the positive electrode material capable of inserting and extracting lithium may be other than the above. Further, two or more kinds of the series of positive electrode materials described above may be mixed in any combination.

(Conductive agent)
As the conductive agent, for example, a carbon material such as carbon black or graphite is used.

(Binder)
Examples of the binder include resin materials such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), styrene butadiene rubber (SBR), and carboxymethyl cellulose (CMC), and these resin materials. At least one selected from a copolymer or the like mainly composed of is used.

(Negative electrode)
The negative electrode 22 has, for example, a structure having a double-sided formation part in which a negative electrode active material layer 22B is provided on both sides of a negative electrode current collector 22A having one main surface and another main surface. In addition, although not shown in figure, you may have the single-sided formation part by which the negative electrode active material layer 22B was provided only in the single side | surface of 22 A of negative electrode collectors. The anode current collector 22A is made of, for example, a metal foil such as a copper foil.

  The first configuration example of the negative electrode active material layer 22B includes, as the negative electrode active material, a first negative electrode material or a second negative electrode material capable of inserting and extracting lithium, and, if necessary, a positive electrode active material You may be comprised including other materials, such as the electrically conductive agent and binder similar to the layer 21B.

  As the first negative electrode material, at least one of the Ge-containing nanoparticles of the first embodiment and the second embodiment described above can be used.

  That is, as the first negative electrode material, at least one or more of Ge / C nanocomposite particles, GeO nanoparticles, Ge simple nanoparticles, and the like can be used.

  As the second negative electrode material, a mixture of a material containing at least Si such as Si particles and the Ge-containing nanoparticles described above can be used. That is, as the second negative electrode material, a mixture of Si particles and at least one or more of Ge / C nanocomposite particles, GeO nanoparticles, Ge simple nanoparticles, and the like can be used. In this case, the Ge-containing nanoparticle functions as a negative electrode active material, but has a conductivity assisting function that improves the conductivity of the Si particles by filling the gaps between the Si particles having a large particle size.

(Separator)
The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 23 may be, for example, a porous film having an average pore diameter of about 5 μm or less, and specifically, a porous film made of a synthetic resin such as polytetrafluoroethylene, polypropylene, or polyethylene, or a ceramic. And a laminate of two or more of these porous membranes. The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte.

(Nonaqueous electrolyte)
The nonaqueous electrolytic solution includes an electrolyte salt and a nonaqueous solvent that dissolves the electrolyte salt.

The electrolyte salt contains, for example, one or more light metal compounds such as lithium salts. Examples of the lithium salt include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium tetraphenylborate _{(LiB (C 6 H 5)} 4), methanesulfonic acid lithium (LiCH ₃ SO _3), lithium trifluoromethanesulfonate (LiCF ₃ SO _3), tetrachloroaluminate lithium (LiAlCl _4), six Examples thereof include dilithium fluorosilicate (Li ₂ SiF ₆ ), lithium chloride (LiCl), and lithium bromide (LiBr). Among these, at least one selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate is preferable, and lithium hexafluorophosphate is more preferable.

  Examples of the non-aqueous solvent include lactone solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, and ε-caprolactone, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, dimethyl carbonate, ethyl methyl carbonate, Carbonate esters such as diethyl carbonate, ether solvents such as 1,2-dimethoxyethane, 1-ethoxy-2-methoxyethane, 1,2-diethoxyethane, tetrahydrofuran or 2-methyltetrahydrofuran, and nitriles such as acetonitrile Nonaqueous solvents such as solvents, sulfolane-based solvents, phosphoric acids, phosphate ester solvents, and pyrrolidones are exemplified. Any one of the non-aqueous solvents may be used alone, or two or more thereof may be mixed and used.

  In addition, it is preferable to use a mixture of a cyclic carbonate and a chain carbonate as the non-aqueous solvent, and it may contain a compound in which a part or all of the hydrogen of the cyclic carbonate or the chain carbonate includes a fluorination. preferable. Examples of the fluorinated compound include fluoroethylene carbonate (4-fluoro-1,3-dioxolan-2-one: FEC) or difluoroethylene carbonate (4,5-difluoro-1,3-dioxolan-2-one: DFEC) is preferably used. This is because even when the negative electrode 22 containing a compound such as silicon (Si), tin (Sn), or germanium (Ge) is used as the negative electrode active material, charge / discharge cycle characteristics can be improved. Of these, difluoroethylene carbonate is preferably used as the non-aqueous solvent. This is because the cycle characteristic improvement effect is excellent.

(Battery manufacturing method)
(Production method of positive electrode)
A positive electrode material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a paste-like positive electrode mixture slurry. Make it. Next, the positive electrode mixture slurry is applied to the positive electrode current collector 21A, the solvent is dried, and the positive electrode active material layer 21B is formed by compression molding with a roll press machine or the like, and the positive electrode 21 is manufactured.

(Method for producing negative electrode)
The first negative electrode material or the second negative electrode material and a binder are mixed to prepare a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to form a paste. A negative electrode mixture slurry is prepared. Next, the negative electrode mixture slurry is applied to the negative electrode current collector 22A, the solvent is dried, and the negative electrode active material layer 22B is formed by compression molding with a roll press or the like, thereby producing the negative electrode 22.

(Preparation of non-aqueous electrolyte)
The nonaqueous electrolytic solution is prepared by dissolving an electrolyte salt in a nonaqueous solvent.

(Battery assembly)
The positive electrode lead 25 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A by welding or the like. Then, the positive electrode 21 and the negative electrode 22 are wound through the separator 23 of the present technology to form a wound electrode body 20.

  Subsequently, the tip of the positive electrode lead 25 is welded to the safety valve mechanism, and the tip of the negative electrode lead 26 is welded to the battery can 11. Thereafter, the wound surface of the wound electrode body 20 is sandwiched between the pair of insulating plates 12 a and 12 b and housed in the battery can 11. After the wound electrode body 20 is accommodated in the battery can 11, a non-aqueous electrolyte is injected into the battery can 11 and impregnated in the separator 23. After that, the safety valve mechanism including the battery lid 13 and the safety valve 14 and the heat sensitive resistance element 17 are fixed to the opening end of the battery can 11 by caulking through the gasket 18. Thereby, the battery of the present technology shown in FIG. 1 is formed.

(Other application examples)
Other application examples of the Ge-containing nanoparticles of the present technology (at least one of the Ge-containing nanoparticles of the first embodiment and the second embodiment described above) include, for example, Ge of the present technology. Infrared-absorbing materials having contained nanoparticles are mentioned. The Ge-containing nanoparticles of the present technology are infrared absorbing materials, and an infrared absorbing material can be formed by embedding in a coating film or resin. Moreover, the infrared photodiode element containing the Ge containing nanoparticle of this technique is mentioned. The Ge-containing nanoparticles of the present technology are semiconductors that absorb infrared rays, and can absorb infrared rays that Si cannot absorb. Moreover, the solar cell which can carry out the coating formation which has Ge containing nanoparticle of this technique is mentioned. In addition to ultraviolet and visible light that can be absorbed by Si, infrared rays of 800 nm to 2500 nm are included, and this infrared light can be absorbed by Ge. Moreover, the electro-optical device which has Ge containing nanoparticle of this technique is mentioned. The Ge-containing nanoparticles of the present technology have a wide band gap and can be fluorescent with visible light, and include electro-optic devices using fluorescence or electron injection emission. As an electrochemical device, the light emitting element containing the Ge containing nanoparticle which light-emits infrared light and visible light is mentioned, for example. In this light-emitting element, the Ge-containing nanoparticles of the present technology make use of the function of emitting light when converted into quantum dots of 20 nm or less. Examples include biorecognition materials that use the light-emitting function of Ge-containing nanoparticles, including Ge-containing nanoparticles of the present technology. Since Ge-containing nanoparticles capable of emitting light are not toxic, they can be introduced into a human body or a living body and applied as a biological recognition material such as a biomarker.

  Specific embodiments of the present technology will be described below with examples, but the present technology is not limited thereto.

<Sample 1>
In sample 1, Ge / C nanocomposite particles were prepared. First, ammonium hydroxide and water are mixed in a solution in which GeOiPr ₄ (germanium isopropoxide) and PVP (polyvinylpyrrolidone) are dissolved in IPA (isopropyl alcohol), and a hydrolysis reaction proceeds in the air at room temperature. I let you. Thus, using the PVP to protect the polymers of GeO ₂ nanoparticles to obtain particle size 50nm about PVP protection GeO ₂ nanoparticles (showing an SEM image in FIG. 4A).

This was subjected to a reduction heat treatment at 800 ° C. for 3 hours in a forming gas (N ₂ / H ₂ ) atmosphere. ) Occurred. FIG. 5 shows an optical photograph of Ge / C nanocomposite powder 51, which is an aggregate of Ge / C nanocomposite particles. As shown in FIG. 5, it was confirmed that the Ge / C nanocomposite powder 51 had almost the same texture as that of a normal carbon material powder.

[Characteristic evaluation of Ge / C nanocomposite particles]
(XRD (X-ray diffraction) measurement, Raman spectroscopy measurement)
XRD measurement and Raman spectroscopic measurement were performed on the PVP-protected GeO ₂ nanoparticles before the reduction heat treatment and the Ge / C nanocomposite particles after the reduction heat treatment. FIG. 6A shows an XRD pattern of PVP-protected GeO ₂ nanoparticles before the reduction heat treatment and an XRD pattern of Ge / C nanocomposite particles after the reduction heat treatment. FIG. 6B shows the Raman spectrum of the PVP-protected GeO ₂ nanoparticles before the reduction heat treatment and the Raman spectrum of the Ge / C nanocomposite particles after the reduction heat treatment.

In FIG. 6A, line a1 shows the XRD pattern of the PVP-protected GeO ₂ nanoparticles before the reduction heat treatment, and line a2 shows the XRD pattern of the Ge / C nanocomposite particles after the reduction heat treatment. In FIG. 6B, line b1 shows the Raman spectrum of the PVP-protected GeO ₂ nanoparticles before the reduction heat treatment, and line b2 shows the Raman spectrum of the Ge / C nanocomposite particles after the reduction heat treatment. As shown in FIGS. 6A and 6B, it was confirmed that the PVP-protected GeO ₂ nanoparticles contain GeO ₂ . Further, it was confirmed that GeO ₂ was reduced to Ge after the reduction heat treatment.

(EDX (Energy Dispersive X-ray Spectroscopy) measurement)
EDX measurement was performed on the Ge / C nanocomposite particles after the reduction heat treatment. The EDX measurement was performed on Ge / C nanocomposite particles deposited on the Si substrate. FIG. 7A shows the EDX spectrum, and FIG. 7B shows the mass composition of the Ge / C nanocomposite particles after the reduction heat treatment.

  As shown in FIGS. 7A and 7B, the Ge concentration of the Ge / C nanocomposite particles was 22% by mass in terms of mass percentage with respect to the mass of carbon.

(XPS measurement)
XPS measurement was performed on the PVP-protected GeO ₂ nanoparticles before the reduction heat treatment and the Ge / C nanocomposite particles after the reduction heat treatment. FIG. 8 shows the XPS spectrum. In FIG. 8, line c1 is an XPS spectrum of PVP-protected GeO ₂ nanoparticles before the reduction heat treatment, and line c2 is an XPS spectrum of Ge / C nanocomposite particles after the reduction heat treatment.

(Evaluation of negative electrode and battery using negative electrode)
(Preparation of negative electrode)
A negative electrode was produced using the produced Ge / C nanocomposite particles. Ge / C nanocomposite particles and PVdF were mixed and dispersed in N-methyl-2-pyrrolidone as a solvent to obtain a negative electrode mixture slurry. Then, after apply | coating and drying on the copper foil which is a negative electrode collector, the negative electrode by which the negative electrode active material layer was formed on the negative electrode collector was obtained by compression molding with a roll press machine.

(Production of half-cell)
A half battery (referred to as half battery 1-1) having the produced negative electrode as a working electrode and a Li foil as a counter electrode was produced. The electrolytic solution was prepared by dissolving 1 mol / kg of LiPF ₆ in a mixed solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed at a weight ratio (EC: DMC = 1: 1). As the separator, a polyethylene microporous membrane was used.

  In addition, as a comparison with Sample 1, instead of Ge / C nanocomposite particles, a half-cell composed of a commercially available Ge powder (Sigma Aldrich, germanium (powder, -100mesh, ≥99.99% trace metals basis)) (Referred to as half-cell 1-2) was also produced.

(Production of battery (lithium ion secondary battery))
(Positive electrode)
A positive electrode using lithium nickel cobalt aluminum composite oxide (LiNi _0.80 Co _0.15 Al _0.05 O ₂ ) as a positive electrode active material was produced as follows.

Lithium nickel cobalt aluminum composite oxide (LiNi _0.80 Co _0.15 Al _0.05 O ₂ ) as a positive electrode active material, graphite as a conductive agent, and polyvinylidene fluoride as a binder were mixed to form a positive electrode mixture. A positive electrode mixture slurry was prepared by dispersing in -methyl-2-pyrrolidone. After that, the positive electrode mixture slurry was applied to an aluminum foil as a positive electrode current collector, dried, and then compression-molded with a roll press to form a positive electrode active material layer on the positive electrode current collector Got.

(Coin cell)
The positive electrode and the negative electrode described above were punched into a circular shape having a diameter of 15 mm to produce a coin cell (size 2016). The electrolyte solution and the separator were the same as the half battery. The utilization factor of the negative electrode active material (Ge / C nanocomposite particles) was designed at 90%.

(Evaluation of half-cell)
The produced half-cells were evaluated at an environmental temperature of 25 ° C., a potential range of 0.0 V to 1.2 V, and a current of 0.1 C. FIG. 9A shows the charge / discharge characteristics of the half-cell. In FIG. 9A, lines p1 and p2 are charge / discharge curves for the half battery 1-1, and lines q1 and q2 are charge / discharge curves for the half battery 1-2. Note that 1C corresponds to a current value for charging and discharging the theoretical capacity in one hour.

(Battery evaluation: cycle characteristics)
The cycle characteristics of the fabricated battery were measured as follows. The manufactured battery was repeatedly charged and discharged. Charging was performed at a charging current of 0.5 C and a charging cut-off voltage of 4.3 V. Discharge was performed at a discharge current of 0.5 C and a discharge cut-off voltage of 2.5 V. And the maintenance rate (percentage with respect to initial stage discharge capacity) of the discharge capacity with respect to the frequency of charging / discharging was plotted. The initial discharge capacity was the discharge capacity at the first discharge after the first charge. FIG. 9B shows a graph in which the maintenance rate is plotted against the number of charge / discharge cycles.

  As indicated by a line q2 in FIG. 9A, the weight energy density of the Ge active material (Ge / C nanocomposite particles) was 1180 mAh / g, which was a favorable value of about 73% of the maximum theoretical capacity. At that time, about 30% of the initial charge (Li → Ge) had an irreversible capacity, and the charge voltage was about 0.2V. These are larger than commercially available Ge powder (commercially available Ge powder is closer to Si powder) and tend to be characteristics closer to SiO than Si. As shown by the line r in FIG. 9B, a capacity retention of 68.2% was observed at the time of 100 cycles, and the downward tendency of deterioration and the cycle characteristics were similar to those of SiO.

Returning to FIG. 8, as shown in the XPS measurement results, reduction from GeO ₂ to Ge is observed, but it can be seen that the peak of GeO ₂ (Ge ⁴⁺ ) remains in the line c2. This is presumably because oxygen is left behind inside the Ge because the Ge / C nanocomposite is reduced Ge derived from GeO ₂ . That is, it is estimated that the state is close to that of GeO, which is consistent with the charge / discharge behavior. In recent years, it has been reported that SiO exhibits better cycle characteristics than Si, and the GeO ₂ -derived Ge / C nanocomposite obtained in Sample 1 has a binding energy of about 29 eV in the XPS spectrum of Ge3d5 / 2. A peak exists near the binding energy of 34 eV, which is considered to be close to GeO, and has a tendency to have high cycle characteristics.

<Sample 2-1>
In Sample 2-1, PVP-protected GeO nanoparticles were prepared in a dry room (no moisture, in an environment with oxygen). Further, this was subjected to a reduction heat treatment to obtain Ge / C nanocomposite particles.

First, in a dry environment (dew point temperature of −30 ° C.) and in an air atmosphere, a reducing agent is added to a solution of GeCl ₄ (germanium tetrachloride) and PVP (polyvinylpyrrolidone) in IPA (isopropyl alcohol) at room temperature. (NaBH ₄ ) was added. This produced PVP protected GeO nanoparticles (shown in SEM image in FIG. 10A).

Next, as a result of reducing heat treatment at 600 ° C. for 1 hour in a forming gas (N ₂ / H ₂ ) atmosphere, Ge / C nanocomposite particles (an SEM image is shown in FIG. 10B) were generated.

(Sample 2-2)
In Sample 2-2, the temperature of the reduction heat treatment was changed to 400 ° C. Except for the above, Ge / C nanocomposite particles were produced in the same manner as Sample 2-1.

[Characteristic evaluation of PVP-protected GeO nanoparticles]
(XPS measurement)
XPS measurement was performed on the PVP-protected GeO nanoparticles before the reduction heat treatment and the Ge / C nanocomposite particles (Sample 2-1 and Sample 2-2) after the reduction heat treatment. 11A and 11B show XPS spectra. In FIG. 11A, line d1 shows the XPS spectrum of Ge2p3 / 2 of the PVP-protected GeO nanoparticles before the reduction heat treatment, line d2 shows the XPS spectrum of Ge2p3 / 2 of sample 2-2, and line d3 shows sample 2-1 The XPS spectrum of Ge2p3 / 2 is shown. In FIG. 11B, the line e1 shows the XPS spectrum of O1s of the PVP-protected GeO nanoparticles before the reduction heat treatment, the line e2 shows the XPS spectrum of O1s of the sample 2-2, and the line e3 shows the XPS spectrum of O1s of the sample 2-1. The spectrum is shown.

(XRD measurement)
XRD measurement was performed on the PVP-protected GeO nanoparticles before the reduction heat treatment and the Ge / C nanocomposite particles (Sample 2-1 and Sample 2-2) after the reduction heat treatment. FIG. 12 shows the XRD pattern. In FIG. 12, line f1 shows the XRD pattern of the PVP-protected GeO nanoparticles before the reduction heat treatment, line f2 shows the XRD pattern of sample 2-2, and line f3 shows the XRD pattern of sample 2-1.

(Half battery)
A half battery (referred to as half battery 2-1) was prepared in the same manner as Sample 1, except that the Ge / C nanocomposite particles prepared in Sample 2-1 were used as the negative electrode active material. A half cell (referred to as half cell 2-2) was prepared in the same manner as Sample 1, except that the PVP-protected GeO nanoparticles prepared in Sample 2-1 were used as the negative electrode active material. Furthermore, as a comparison with sample 2-1, instead of Ge / C nanocomposite particles, it is composed of a negative electrode using commercially available Ge powder (Sigma, Aldrich, germanium (powder, -100mesh, ≥99.99% trace metals basis)) A half cell (referred to as half cell 2-3) was prepared.

(Evaluation of half-cell)
The produced half-cells were evaluated at an environmental temperature of 25 ° C., a potential range of 0.0V-1.2V or 0.0V-1.4V, and a current of 0.1C. FIG. 13 shows the charge / discharge characteristics of the half-cell 2-1 and the half-cell 2-3. FIG. 14 shows the charge / discharge characteristics of the half-cell 2-2. In FIG. 13, lines u1 and u2 are charge / discharge curves for the half battery 2-1, and lines s1 and s2 are charge / discharge curves for the half battery 2-3. In FIG. 14, lines v <b> 1 and v <b> 2 are charge / discharge curves for the half-cell 2-2.

In sample 2-1, when Ge is reduced with NaBH _4, it is slightly oxidized in the atmosphere, so the consumption reaction of GeCl ₄ is accelerated and nanoparticles with a particle size of 50 nm (the SEM image is shown in FIG. 10A). Was synthesized. As a result of XPS measurement, as shown in FIG. 11A, it was found that the synthesized nanoparticles were not Ge or GeO ₂ but GeO.

As in Sample 3 described later, in the case of normal atmospheric environment synthesis, since it was converted to GeO ₂ , moisture is the main oxidant of Ge, and the oxidizing power of oxygen with respect to Ge is small, in a dry environment (no moisture, oxygen In a certain environment), it is conceivable that GeO nanoparticles are generated.

Further, as a difference from Si, Ge has a stable 2+ oxidation number, which contributes to GeO generation. When the nanoparticles were subjected to a reduction heat treatment at 400 ° C. and 600 ° C. for 1 h, as shown in FIG. 11A, it was found that at 400 ° C., Ge and GeO ₂ were separated by 2GeO → Ge + GeO ₂ . . In the case of SiO, it is known to separate by high-temperature treatment at 1000 ° C.

Further, as shown in FIGS. 11A and 11B, it was suggested that when reduction heat treatment at 600 ° C. was performed, GeO ₂ peak reduction and O1s peak reduction reduced to Ge. In addition, even after the treatment at 600 ° C., the particle diameter is about 50 nm close to that of GeO nanoparticles (see the SEM image in FIG. 10B), suggesting that the particles were reduced to Ge nanoparticles without causing aggregation of the nanoparticles. It was done.

As shown in the XRD patterns before and after the reduction heat treatment at 400 ° C. and 600 ° C. in FIG. 12, a process in which amorphous GeO was reduced to Ge crystals as suggested by XPS was observed. Since GeO is an intermediate between Ge and GeO ₂ , it is considered that GeO was reduced at 600 ° C. lower than the reduction temperature (800 ° C.) of GeO ₂ .

  As shown in the characteristics of the half-cell 2-1 of the GeO-derived Ge nanoparticle-supported carbon (after 600 ° C. treatment) in FIG. 13, the charge / discharge capacity is equivalent to that of commercially available Ge, and Ge / C having a particle size of 50 nm. It was confirmed that the nanocomposite particles functioned as a Ge active material.

<Sample 3>
In sample 3, GeO ₂ nanoparticles were produced in the glove box. Further, this was reduced to obtain Ge / C nanocomposite particles. In sample 3, unlike sample 2, synthesis was performed in a normal environment (an environment with moisture), not in a dry environment. The synthesis was performed in a glove box.

First, a reducing agent (NaBH ₄ ) was mixed at room temperature with a solution in which GeCl ₄ (germanium tetrachloride) and PVP (polyvinylpyrrolidone) were dissolved in ethylene glycol in a normal environment and in an air atmosphere. This produced GeO ₂ nanoparticles. GeO ₂ nanoparticles seemed to have a cluster size (typically a size of 5 nm or less), and particles could not be confirmed by SEM or XRD. On the other hand, it turns out that Ge crystallizes by the below-mentioned 600 degreeC reduction heat processing.

Next, as a result of reducing heat treatment at 600 ° C. for 3 hours in a forming gas (N ₂ / H ₂ ) atmosphere, Ge / C nanocomposite particles (an SEM image is shown in FIGS. 15A and 15B) are obtained. occured.

[Characteristic evaluation of Ge / C nanocomposite particles]
(Raman spectroscopy measurement)
Raman spectroscopic measurements were performed on the PVP-protected GeO ₂ nanoparticles before the reduction heat treatment and the Ge / C nanocomposite particles after the reduction heat treatment. FIG. 16 shows the measurement results. In FIG. 16, the line w1 shows the Raman spectrum for the PVP-protected GeO ₂ nanoparticles before the heat treatment for reduction treatment, and the line w2 shows the Raman spectrum for the Ge / C nanocomposite particles after the heat treatment for reduction treatment.

In sample 3, unlike the hydrolysis of Ge isopropoxide in sample 1, GeCl ₄ is reduced with NaBH ₄ at room temperature at the time of synthesis, so that Ge nanoparticles having a cluster size (5 nm or less) can be synthesized at room temperature. However, since Ge was an unstable cluster size, it was aggregated by heat treatment, and the Ge crystal size was enlarged to about 500 nm.

4). Other embodiment (modification)
The present technology is not limited to the above-described embodiments of the present technology, and various modifications and applications are possible without departing from the scope of the present technology.

  For example, the numerical values, structures, shapes, materials, raw materials, manufacturing processes and the like given in the above-described embodiments and examples are merely examples, and different numerical values, structures, shapes, materials, raw materials, and the like as necessary. A manufacturing process or the like may be used.

  The configurations, methods, processes, shapes, materials, numerical values, and the like of the above-described embodiments and examples can be combined with each other without departing from the gist of the present technology.

  The battery of the application example has been described with respect to a battery having a cylindrical battery structure and a battery having a wound structure in which an electrode is wound, but is not limited thereto. For example, the same applies to batteries having other battery structures such as a laminate film type battery using a laminate film for the exterior, a stack type having a structure in which electrodes are stacked, a square type, a coin type, a flat type or a button type battery. In addition, the present technology can be applied. In the stack type, for example, a battery structure in which a positive electrode and a negative electrode are stacked via a single-sheet separator, a battery structure in which a positive electrode and a negative electrode are stacked through a single strip-shaped separator folded, and a negative electrode are sandwiched Examples thereof include a battery structure in which a positive electrode and a negative electrode are stacked through a pair of separators folded by spelling in a state. The electrolyte is not limited to a liquid electrolyte.

  The present technology can also take the following configurations.

[1]
The Gibbs formation free energy ΔG for the oxygen molecule (1 mol) is smaller than the Gibbs formation free energy ΔG for the oxygen molecule (1 mol) of Ge in the Ellingham diagram, C, H ₂ , Zn, K, Na, Cr, Mn, Ge oxide nanoparticles are reduced by one element composed of at least one of V, Si, Ti, Al, Mg, Ca, Sc, Sr, Nb, Li, Ba, In, Y, Hf, Zr, and Ta. A method for producing Ge-containing nanoparticles, comprising preparing nanoparticles containing at least Ge.
[2]
The one element is C,
The protective polymer containing C and Ge alkoxide are mixed, the hydrolysis reaction proceeds to prepare the Ge oxide nanoparticles whose surface is protected by the protective polymer,
The method for producing Ge-containing nanoparticles according to [1], wherein the Ge oxide nanoparticles are reduced by the C.
[3]
The method for producing Ge-containing nanoparticles according to [2], wherein the protective polymer is an alcohol-soluble organic polymer compound.
[4]
The method for producing Ge-containing nanoparticles according to any one of [2] to [3], wherein the nanoparticles containing at least Ge are nanocomposite particles containing at least Ge and C.
[5]
The method for producing Ge-containing nanoparticles according to any one of [1] to [4], wherein the reduction is performed in an atmosphere of nitrogen, argon, hydrogen, or a mixed gas thereof [6].
The method for producing Ge-containing nanoparticles according to any one of [1] to [5], wherein the reduction temperature is 1000 ° C. or lower.
[7]
The Ge oxide nanoparticles are GeO _x (0.5 <x <1.5) nanoparticles,
Any of [1] to [6], wherein the halogenated Ge is reduced with a reducing agent in a dry environment having a dew point of −30 ° C. or lower to prepare the GeO _x (0.5 <x <1.5) nanoparticles. The manufacturing method of Ge containing nanoparticle as described in any one of.
[8]
The method for producing Ge-containing nanoparticles according to [7], wherein the reducing agent is an alkali element and / or a hydrogen-containing substance.
[9]
The one element is C,
In a dry environment with a dew point of −30 ° C. or lower, after dissolving the protective polymer containing C and the halogenated Ge in an alcohol solvent, the halogenated Ge is reduced with a reducing agent, and the surface is protected by the protective polymer. The method for producing Ge-containing nanoparticles according to any one of [7] to [8], wherein the GeO _x (0.5 <x <1.5) nanoparticles are prepared.
[10]
A method for producing Ge-containing nanoparticles, wherein GeO _x (0.5 <x <1.5) nanoparticles are prepared by reducing halogenated Ge with a reducing agent in a dry environment having a dew point of −30 ° C. or lower.
[11]
Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).
[12]
The GeO _x (0.5 <x <1.5) is a single-phase GeO _x (0.5 <x <1.5) having a single peak near the binding energy 1218 eV of the Ge2p2 / 3 spectrum of XPS. The Ge-containing nanoparticle according to [11].
[13]
The Ge-containing nanoparticle according to any one of [11] to [12], wherein the GeO _x (0.5 <x <1.5) is amorphous.
[14]
A positive electrode;
A negative electrode,
With electrolyte,
The negative electrode is a battery containing Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).
[15]
The battery according to [14], wherein the negative electrode further contains Si.
[16]
An infrared absorbing material having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).
[17]
An infrared photodiode device having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).
[18]
A solar cell having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).
[19]
A light-emitting element having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).
[20]
A biorecognition material having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 12a, 12b ... Insulating plate, 13 ... Battery cover, 14 ... Safety valve, 14a ... Projection part, 15 ... Disc holder, 16 ... Shut-off disc, 16a ... Hole, 17 ... Heat sensitive resistor, 18 ... Gasket, 19 ... Subdisk, 20 ... Winding electrode body, 21 ... Positive electrode, 21A ... Positive electrode collection Electrode, 21B ... Positive electrode active material layer, 22 ... Negative electrode, 22A ... Negative electrode current collector, 22B ... Negative electrode active material layer, 23 ... Separator, 24 ... Center pin, 25 ... Positive lead, 26 ... Negative lead

Claims (20)

The Gibbs formation free energy ΔG for the oxygen molecule (1 mol) is smaller than the Gibbs formation free energy ΔG for the oxygen molecule (1 mol) of Ge in the Ellingham diagram, C, H ₂ , Zn, K, Na, Cr, Mn, Ge oxide nanoparticles are reduced by one element composed of at least one of V, Si, Ti, Al, Mg, Ca, Sc, Sr, Nb, Li, Ba, In, Y, Hf, Zr, and Ta. A method for producing Ge-containing nanoparticles, comprising preparing nanoparticles containing at least Ge. The one element is C,
The protective polymer containing C and Ge alkoxide are mixed, the hydrolysis reaction proceeds to prepare the Ge oxide nanoparticles whose surface is protected by the protective polymer,
The method for producing Ge-containing nanoparticles according to claim 1, wherein the Ge oxide nanoparticles are reduced by the C.   The method for producing Ge-containing nanoparticles according to claim 2, wherein the protective polymer is an alcohol-soluble organic polymer compound.   The method for producing Ge-containing nanoparticles according to claim 3, wherein the nanoparticles containing at least Ge are nanocomposite particles containing at least Ge and C.   The method for producing Ge-containing nanoparticles according to claim 1, wherein the reduction is performed in an atmosphere of nitrogen, argon, hydrogen, or a mixed gas thereof.   The method for producing Ge-containing nanoparticles according to claim 1, wherein the reduction temperature is 1000 ° C or lower. The Ge oxide nanoparticles are GeO _x (0.5 <x <1.5) nanoparticles,
The Ge-containing nanoparticle according to claim 1, wherein the GeO _x (0.5 <x <1.5) nanoparticles are prepared by reducing halogenated Ge with a reducing agent in a dry environment having a dew point of −30 ° C. or less. Particle manufacturing method.   The method for producing Ge-containing nanoparticles according to claim 7, wherein the reducing agent is an alkali element and / or a hydrogen-containing material. The one element is C,
In a dry environment with a dew point of −30 ° C. or lower, after dissolving the protective polymer containing C and the halogenated Ge in an alcohol solvent, the halogenated Ge is reduced with a reducing agent, and the surface is protected by the protective polymer. The method for producing Ge-containing nanoparticles according to claim 7, wherein the GeO _x (0.5 <x <1.5) nanoparticles are prepared. A method for producing Ge-containing nanoparticles, wherein GeO _x (0.5 <x <1.5) nanoparticles are prepared by reducing halogenated Ge with a reducing agent in a dry environment having a dew point of −30 ° C. or lower. Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5). The GeO _x (0.5 <x <1.5) is a single-phase GeO _x (0.5 <x <1.5) having a single peak near the binding energy 1218 eV of the Ge2p2 / 3 spectrum of XPS. The Ge-containing nanoparticle according to claim 11. The Ge-containing nanoparticle according to claim 11, wherein the GeO _x (0.5 <x <1.5) is amorphous. A positive electrode;
A negative electrode,
With electrolyte,
The negative electrode is a battery containing Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).   The battery according to claim 14, wherein the negative electrode further contains Si. An infrared absorbing material having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5). An infrared photodiode device having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5). A solar cell having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5). A light-emitting element having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5). A biorecognition material having Ge-containing nanoparticles containing at least GeO _x (0.5 <x <1.5).