JP7433816B2 - Nanostructure manufacturing method and device - Google Patents

Description

The present invention relates to a nanostructure manufacturing method and apparatus for manufacturing nanostructures used in electrodes of lithium ion batteries and the like.

BACKGROUND ART Conventionally, electrodes have been developed in order to improve the performance of lithium ion batteries used in electric vehicles.
For example, in such development, there are cases where electrodes are used in which Si is combined with Si oxide or Li-Si oxide. Conventionally, electrodes have been formed by mechanically mixing Si oxide or Li--Si oxide with powdered Si or by heat treatment.

Japanese Patent Application Publication No. 2009-076372 Japanese Patent Application Publication No. 2014-220216 International Publication WO2013-099278 Publication F. F. Cao, J. W. Deng, S. Xin, H. X. Ji, O. G. Schmidt, L. J. Wan and Y. G. Guo, Adv. Mater., 2011, 23, 4415-4420. H. Jia, P. Gao, J. Yang, J. Wang, Y. Nuli and Z. Yang, Adv. Ener, Mater., 2011, 1, 1036-1039. S. H. Ng, J. Wang, D. Wexler, S. Y. Chew and H. K. Liu, J. Phys. Chem. C, 2007, 111, 11131-11138. H. Takezawa, S. Ito, H. Yoshizawa and T. Abe, Electrochim. Acta, 2017, 229, 438-444. R. Lv, J. Yang, J. Wang and Y. NuLi, Journal of Power Sources, 2011, 196, 3868-3873.

However, with the conventional electrodes mentioned above, the cycle characteristics, which indicate the capacity retention rate of the battery after repeated charging and discharging, are better than when only Si is used for the electrode, but further improvements are desired. .
In other words, in a conventional electrode made only of Si, as shown in FIG. 21, the particles crack due to the strain caused by the volume change of Si and Li _x Si during charging and discharging, which cuts off the electrical path and reduces the capacity. It invites. In the composite negative electrode, the matrix component made of Si oxide or Li-Si oxide alleviates strain, thereby improving the capacity retention rate. However, there are problems in that a side reaction of the matrix components occurs during the first charge and the reversible capacity decreases, and the matrix components themselves do not contribute to the capacity, resulting in a decrease in the capacity per composite.

The present invention is intended to solve the above-mentioned problems, and provides a nanostructure manufacturing method and an apparatus for manufacturing a nanostructure that exhibits less decrease in discharge capacity due to charging and discharging when used in a battery or the like. The purpose is to

In order to solve the above-mentioned problems of the prior art and achieve the above-mentioned objects, the method for producing a nanostructure of the present invention involves irradiating a material to be deposited with metal atoms of Li and Si from an arc plasma deposition source. A nano-sized composite film consisting of Si, SiOx, Li-Si-O and Li ₂ CO ₃ is obtained by depositing nano-sized particles of the evaporation material with an average particle diameter of 5 to 30 nm on the material to be evaporated. Form a structure.

According to this configuration, it is possible to manufacture a nanostructure in which nano-sized particles of the vapor deposition material having an average particle size of 5 to 30 nm are deposited and are suitable for batteries and the like.

The nanostructure can be applied to battery electrodes and the like.

Preferably, a deposition material installation step of installing the deposition object in a vacuum chamber before the nanostructure formation step, and a deposition material installation step of installing the deposition material before the nanostructure formation step. and an installation process.

According to this configuration, the object to be evaporated and the evaporation material can be placed in the vacuum chamber in advance.

Preferably, the arc plasma deposition source is configured by coaxially disposing a cylindrical anode electrode and a cylindrical cathode electrode to which the evaporation material is electrically connected inside the anode electrode, and The discharge voltage applied to the anode electrode is 70V or more and 1000V or less.

Preferably, the method further includes a setting step of setting the number of shots N of the vapor deposition material, the discharge voltage Va, the capacitor capacity C, and the frequency F before the nanostructure forming step.

Preferably, in the nanostructure forming step, the vapor deposition material is irradiated onto the vapor deposition material while rotating the vapor deposition material.

Preferably, the nanosized particles are metals or metal oxides.

Preferably, the nano-sized particles are at least one of Zr, Li, Si, Cu, and Nb.

Preferably, a plurality of the vapor deposition materials are irradiated onto the material to be vapor deposited.

Preferably, the plurality of vapor deposition materials include any combination of Li and Zr, Si and Cu, and Li and Si.

The nanostructure manufacturing apparatus of the present invention is installed in a vacuum chamber, and includes a holding means for holding a material to be deposited, and an arc plasma deposition source for irradiating the material to be deposited with a metal atom vapor deposition material, and includes a Li and irradiating the vapor deposition material of metal atoms of Si from the arc plasma deposition source to the vapor deposition material, and depositing nano-sized particles of the vapor deposition material on the vapor deposition material, Si, SiOx, Li-Si- A nanostructure which is a composite film consisting of O and Li ₂ CO ₃ is formed.

The nanostructure manufacturing method of the present invention includes a vacuum chamber, a deposition target placed in the vacuum chamber, a first vapor deposition material and a second vapor deposition material placed in the vacuum chamber, and a second vapor deposition material placed in the vacuum chamber. a first anode electrode that causes a first arc plasma discharge between the first vapor deposition material; a second anode electrode that causes a second arc plasma discharge between the second vapor deposition material; A first cathode electrode coaxially provided inside the first anode electrode and spaced apart from the wall surface of the first anode electrode, and a second cathode electrode coaxially provided inside the second anode electrode. and a second cathode electrode provided at a certain distance from the wall surface of the anode electrode, the method comprises: installing a material to be deposited in the vacuum chamber; a vapor deposition material installation step of installing Si as a first vapor deposition material and Li as a second vapor deposition material in the vacuum chamber; and an oxygen pressure adjustment step of adjusting oxygen pressure in the vacuum chamber; The number of shots of the first vapor deposition material N(1), the number of shots of the second vapor deposition material N(2), and a first anode electrode that causes a first arc plasma discharge between the first vapor deposition material and the first vapor deposition material. and a second discharge voltage V(2) to be applied to the second anode electrode to cause a second arc plasma discharge between the second vapor deposition material and the second vapor deposition material. the first evaporation material and the second evaporation material onto the material to be evaporated by arc plasma discharge under the oxygen pressure adjusted in the oxygen pressure adjustment step and the conditions set in the setting step; Forming a nanostructure by irradiating and depositing Si and Li nano-sized particles with an average particle size of 5 to 30 nm on the deposited body to form a nanostructure that satisfies the following condition (1) on the deposited body. It has a process and .
Li/Si ratio y and O/Si ratio z are “0<y,z≦4” and “0<x≦2”
...(1)

The nanostructure manufacturing method of the present invention includes a vacuum chamber, a deposition target placed in the vacuum chamber, a first vapor deposition material and a second vapor deposition material placed in the vacuum chamber, and a second vapor deposition material placed in the vacuum chamber. a first anode electrode that causes a first arc plasma discharge between the first vapor deposition material; a second anode electrode that causes a second arc plasma discharge between the second vapor deposition material; A first cathode electrode coaxially provided inside the first anode electrode and spaced apart from the wall surface of the first anode electrode, and a second cathode electrode coaxially provided inside the second anode electrode. and a second cathode electrode provided at a certain distance from the wall surface of the anode electrode, the method comprises: installing a material to be deposited in the vacuum chamber; a vapor deposition material installation step of installing Si as a first vapor deposition material and Li as a second vapor deposition material in the vacuum chamber; and an oxygen pressure adjustment step of adjusting oxygen pressure in the vacuum chamber; The number of shots of the first vapor deposition material N(1), the number of shots of the second vapor deposition material N(2), and a first anode electrode that causes a first arc plasma discharge between the first vapor deposition material and the first vapor deposition material. and a second discharge voltage V(2) to be applied to the second anode electrode to cause a second arc plasma discharge between the second vapor deposition material and the second vapor deposition material. the first evaporation material and the second evaporation material onto the material to be evaporated by arc plasma discharge under the oxygen pressure adjusted in the oxygen pressure adjustment step and the conditions set in the setting step; Forming a nanostructure by irradiating and depositing Si and Li nano-sized particles with an average particle size of 5 to 30 nm on the deposited body to form a nanostructure that satisfies the following condition (1) on the deposited body. It has a process.
Li/Si ratio y and O/Si ratio z are “0<y,z≦4” and “0<x≦2”
...(1)

Preferably, in the oxygen pressure adjusting step, the oxygen pressure is set to 3×10 ⁻⁴ to 5 Pa, and in the setting step, the number of shots N(1) is set to 300 to 18,000, and the number of shots N(2) is set to 3×10 −4 to 5 Pa. is set to 200 to 4800, the first discharge voltage V(1) is set to 100 to 200V, and the second discharge voltage V(2) is set to 100 to 150.

According to the present invention, it is possible to provide a nanostructure manufacturing method and an apparatus for manufacturing a nanostructure whose discharge capacity decreases little due to charging and discharging when used in a battery or the like.

FIG. 2 is a diagram showing discharge capacity versus cycle number obtained from a constant current charge/discharge test of a battery using a nanostructure according to an embodiment of the present invention. FIG. 3 is a diagram showing the neutron scattering length density of the nanostructure of the first example of the present invention and the main constituent materials predicted from it. FIG. 3 is a diagram showing the neutron scattering length density of a material. 1 is a schematic diagram of a nanostructure manufacturing apparatus according to an embodiment of the present invention. 1 is a diagram for explaining a nanostructure manufacturing apparatus used for manufacturing a nanostructure according to a first embodiment of the present invention. FIG. FIG. 6 is a diagram for explaining conditions for forming a synthetic film on a deposition target using the nanostructure manufacturing apparatus shown in FIG. 5; FIG. 2 is an SEM diagram illustrating the state of a nanostructure film obtained by using Zr as a vapor deposition material by the APD method of the embodiment of the present invention. FIG. 2 is a STEM diagram for explaining the state of a nanostructure film obtained by using Si and Li as vapor deposition materials by the APD method of the embodiment of the present invention. FIG. 3 is a diagram showing the state of a film synthesized by a sputtering method. FIG. 2 is a diagram showing an SEM of the surface of a nanostructure containing Si nanosized particles before charging and discharging. FIG. 11 is a diagram showing an SEM of the surface of the nanostructure containing Si nanosized particles shown in FIG. 10 after 30 cycles of charging and discharging. FIG. 3 is a diagram showing an SEM of the surface of a nanostructure containing Li--Si--O and Li--C--O in addition to Si nano-sized particles before charging and discharging. FIG. 13 is a diagram showing an SEM of the surface of the Si nano-sized particles shown in FIG. 12 as well as Li--Si--O and Li--C--O nanostructures after 425 cycles of charging and discharging. FIG. 3 shows EDX mapping of the surface of a nanostructure containing Cu nanosized particles in addition to Si nanosized particles after 30 cycles of charging and discharging. FIG. 3 shows EDX mapping of the surface of a nanostructure containing Li-Si-O and Li-C-O nanosized particles in addition to nanosized particles of Si after 425 charge/discharge cycles. FIG. 2 is an image diagram of charging and discharging when a nanostructure containing Li-Si-O and Li-C-O nanosized particles in addition to Si nanosized particles is used as a battery electrode. FIG. 2 is a diagram for explaining an atomic force microscope image of a nanostructure synthesized with 10,000 shots of Si in an embodiment of the present invention. FIG. 2 is a diagram for explaining an atomic force microscope image of a nanostructure synthesized with 10,000 shots of Si in an embodiment of the present invention. FIG. 2 is a diagram for explaining an atomic force microscope image of a nanostructure synthesized with a Li/Si ratio y=3.6 in an embodiment of the present invention. It is a flowchart for explaining the manufacturing method of a nanostructure using a nanostructure manufacturing apparatus. FIG. 3 is a diagram for explaining the problem that particles break due to distortion caused by volume changes of Si and LixSi during charging and discharging.

Hereinafter, a nanostructure manufacturing method and apparatus for manufacturing a nanostructure according to an embodiment of the present invention will be described.

[the purpose]
In Si, which is a high-capacity negative electrode material, the active material particles are pulverized due to volumetric expansion and contraction due to Li alloying, and the conductive paths for electrons and ions are interrupted, resulting in a decrease in capacity. Cycle characteristics were improved by securing a conductive path by suppressing volumetric expansion and contraction by nanostructures (Non-patent Documents 1, 2) and by combining with conductive additives carbon and ionically conductive substances (Non-patent Documents 3, 4). . On the other hand, the problem is that the initial charge/discharge efficiency and the Si content per volume are small. In this embodiment, the initial charge/discharge efficiency and the utilization rate of Si are improved by compounding Si and Li oxide in a dense and highly dispersed manner. Si-O-C and Li-Si-O-C composite films were synthesized using arc plasma deposition (APD), which allows nanoparticles to be deposited at high density, and their structures and electrochemical properties were investigated. .

[experiment]
Si-O-C and Li-Si-O-C films were synthesized on Cu foil (Φ10) or Al ₂ O ₃ single crystal substrate by arc plasma deposition. B-doped Si/C, Li-metal/C was used as a target, the substrate temperature was set to room temperature, and the oxygen pressure in the chamber was set to 3x10 ^-4 Pa. The discharge voltage V and capacitor capacity C during discharge to the target were set to Si: 100-150 V, 360 μF, and Li: 100 V, 360 μF.

The number of discharges (pulses) was controlled so that the Li deposition rate was 0.066 nm pulses ^-1 , the Si deposition rate was 0.044 nm pulses ^-1 , and Li _1.4 -Si. The structure of the obtained sample was evaluated by XRR, XPS, AFM, and TEM. The electrochemical properties were determined using a 2032 type coin cell, counter electrode: Li, electrolyte: 1 mol dm ^-3 LiPF ₆ in EC:DEC (3:7 vol.), and a discharge voltage range of 0.02 to 1.5 V ( A charge/discharge test was conducted using vsLi/Li ⁺ ). The charge/discharge capacity (mAh gSi ⁻¹ ) was calculated from the amount of Si content predicted from the deposition rate. In order to compare the electrode structure before and after the charge/discharge reaction, the cell after cycling was disassembled in an Ar atmosphere glove box, and SEM-EDX observation was performed.

[Results and Discussion]
XRR, AFM, and TEM revealed that the Si-O-C and Li-Si-O-C films had a thickness of 60 nm and a dense structure without voids. According to the XPS spectrum, Si, SiC, and SiOx were present in the Si-O-C film. No Li-Si alloy was observed in the Li-Si-O-C film, which was a composite film consisting of Si, SiOx, Li-Si-O, and Li ₂ CO ₃ . The oxygen is taken from the residual oxygen in the chamber.

FIG. 1 is a graph showing discharge capacity versus cycle number obtained from a constant current charge/discharge test.
The capacity of the Si-O-C film decreased to 1286 mAhgSi ^-1 at the 130th cycle, whereas the capacity of the Li-Si-O-C film was maintained at 2776 mAhgSi ^-1 even at the 425th cycle. The initial charging/discharging efficiency, which is the ratio between the charging capacity and the discharging capacity in the first cycle, was 62%.

The discharge capacity per volume of the Li-Si-O-C film was 347 μAh cm ⁻² μm ⁻¹ at the 425th cycle, which was higher than that of the Li-Si film (15 μm, 40 μAh cm ⁻² μm ⁻¹ @50th). Regarding coulombic efficiency, Li-
The Si-O-C film showed a high value of 99.6% at the 425th cycle. Ex-situ SEM-EDX revealed that cracks occurred throughout the Si film after charging and discharging, but continuous Si distribution was observed in Li-Si-O-C even after 425 cycles.
We have demonstrated that it is possible to increase the charge/discharge efficiency, capacity retention rate, and active material utilization rate of Si negative electrodes by synthesizing a high-density structure containing an appropriate amount of Li-Si-O during synthesis. I found it.

The nanostructure of this embodiment contains, for example, nano-sized particles having an average particle diameter of 5 to 30 nm.
The nano-sized particles have a predetermined density. Regarding the compactness of the nano-sized particles of this embodiment, for example, the bulk density is 90 to 100% of the theoretical value.
Further, the nano-sized particles have a predetermined dispersibility. The thin film obtained after nanoparticle synthesis has a value of 90% or more of the theoretical density of the material in question. Furthermore, when a cross section of the thin film is observed under an electron microscope, the shading caused by the atomic distribution is dispersed to such an extent that it cannot be observed.

The elemental species contained in the nanostructure of this embodiment is a typical metal or a transition metal, and is, for example, at least one of Zr, Li, Si, Cu, and Nb.

Further, the nanostructure of this embodiment contains, for example, a plurality of nanosized substances.
As a result, complexes (compounds) of Li ₂ ZrO ₃ , Li ₄ SiO ₄ , Li ₂ CO ₃ , etc. are present within the nanostructure.

Other embodiments contain composites of SiC and SiO _x , each of which is the nanosized particle.

Further, in another embodiment, the nanosized particles are Si and have a bonding state of Si, SiC, and SiO _x on the surface of the nanostructure.

A further example of the nanostructure of this embodiment will be described below.
[First example]
The nanostructure of this example is a nanostructure obtained by depositing nanosized particles, and the nanosized particles are Si and Li with an average particle size of 5 to 30 nm.
Further, the nanostructure satisfies the following condition (1).

Condition (1):
The Li/Si ratio y and the O/Si ratio z are “0<y,z≦4” and “0<x≦2”. The ratios y and z are, for example, molar ratios estimated from ICP pair analysis.

Here, it has been found that by configuring the nanostructure so as to satisfy each of the following requirements, a higher discharge capacity can be obtained than when the requirements are not satisfied.
- Contain Li - Make the Li/Si ratio y 4 or less. The ratio y is more preferably 0.4 to 1.6.
- The O/Si ratio z should be 4 or less. - The nano-sized particles of Si and Li should have an average particle size of 5 to 30 nm. - The SiO _x should be 0<x≦2.

The reason why the above-mentioned ratio y is preferably in the range of 0.4 to 1.6 is as follows.
As a result of measuring the constituent element ratio of the Li-Si-O-C film through compositional analysis (ICP), the relationship with capacity was found to be that when the ratio y was 1.6 or less, the capacity/discharge capacity at 50 cycles was 2000 mAh per Si. Becomes g-1 or higher. It was also found that when the ratio y was 0.4 to 1.6, the capacity retention rate at 70 cycles was 50% or more.

Furthermore, as shown in FIG. 2, a high discharge capacity can be obtained when Li/Si is 1.4.

FIG. 2 is a diagram showing the neutron scattering length density of the nanostructure of the first example and the main constituent materials predicted from it.
The measured data obtained by changing the Li/Si ratio y within the range of 0<x≦4 are shown in FIG.
The information shown in FIG. 2 is the real number component of the neutron scattering length density of Li-Si-O structures synthesized under different Li/Si ratios and oxygen pressures in the first example. This is a value analyzed from neutron reflectance measurements and includes information on the composition of the film. From a comparison with data for existing substances, the upper limit for both ratios y and z is 4. Further, by controlling the Li/Si ratio (≦4) and oxygen pressure, it is made into a composite and intermediate composition information is obtained. Neutron reflectance measurement provides information on the main components contained in nanostructures.

FIG. 3 is a diagram showing the neutron scattering length density of the material.
The following are the conditions under which it has been confirmed that a nanostructure can be obtained. That is, since nanoparticles are observed on the surface using an atomic force microscope, it is thought that a structure is obtained by the deposition of nanoparticles. Factors that have a large influence on whether or not a nanostructure can be obtained are the oxygen pressure in the vacuum chamber 2 and the Li/Si ratio.
By setting the oxygen pressure in the vacuum chamber 2 to 3×10 ⁻⁴ to 5 Pa, a nanostructure with excellent discharge characteristics was obtained.

[Second example]
The nanostructure of the second example has a surface in which Li--Si--O, Si, and SiOx are bonded in the nanostructure of the second example.
In this way, it was found that by forming the surface in a bonded state of Li-Si-O, Si, and SiOx, a higher discharge capacity could be obtained than in the case of a bonding state of one or two of these components. .
It has also been found that by setting the theoretical value of the bulk density of nanosized particles in the range of 90 to 100%, a higher discharge capacity can be obtained than in other cases.
Note that on the surface of the nanostructure of the first example described above, at least one of Li--Si--O, Si, and SiOx is in a bonded state.

[Nanostructure manufacturing device 1]
FIG. 4 is a schematic diagram of a nanostructure manufacturing apparatus 1 according to an embodiment of the present invention.
The nanostructure manufacturing apparatus 1 synthesizes a nanostructure film by arc plasma deposition (APD).
The inventor discovered that the nanostructure of this embodiment can be synthesized by using APD under predetermined conditions.
In the APD method, a vapor deposition material 11 ionized with high plasma energy is deposited on an opposing object 10 (substrate), and is used as a coating material with high ion energy and excellent adhesion to the object 10. Ru.

The nanostructure manufacturing apparatus 1 according to this embodiment includes a cylindrical vacuum chamber 2.
Inside the vacuum chamber 2, a deposition material holding section 4 is rotatably provided.
A deposition target 10 is held on a substrate 8 by the deposition target holding section 4 .
The substrate 8 rotates in conjunction with the rotation of the deposition material holding section 4, and nanoparticles are uniformly formed on the deposition target 10 held by the substrate 8.

Further, as shown in FIG. 4, a coaxial vacuum arc evaporation source 5 is housed within the vacuum chamber 2.

As shown in FIG. 4, the coaxial vacuum arc evaporation source 5 includes a cylindrical or cylindrical cathode electrode 12 made of a material for producing metal nanoparticles, an evaporation material 11 fixed to the cathode electrode 12, A cylindrical anode electrode 23 made of stainless steel or the like, a cylindrical trigger electrode (for example, a ring-shaped trigger electrode) 13 made of stainless steel or the like, and between the vapor deposition material 11 and the trigger electrode 13. It consists of a disc-shaped or cylindrical insulator (hereinafter also referred to as a hat-shaped insulator) 14 provided to separate the two, and these are coaxially attached.

Vapor deposition material 11 is provided facing container 10 . Although not shown, the three components of the vapor deposition material 11, the insulator 14, and the trigger electrode 13 are coaxially attached to each other by screws or the like.

Although not shown, the anode electrode 23 is attached to a vacuum flange with a support so that its angle with respect to the container 10 can be changed, and this vacuum flange is attached to the upper surface of the vacuum chamber 11.

The cathode electrode 12 is coaxially provided inside the anode electrode 23 and spaced a certain distance from the wall surface of the anode electrode. The cathode electrode 12 has the vapor deposition material 11 fixed to at least its tip (corresponding to the end on the opening side of the anode electrode 23).

The vapor deposition material 11 is a metal atom.
In this embodiment, Li, Zr, Si, Cu, Nb, etc. are illustrated as metal atoms.

The trigger electrode 13 is attached to the vapor deposition material 11 or the cathode electrode 12 with an insulator 14 made of alumina or the like sandwiched therebetween.

The insulator 14 is attached to insulate the vapor deposition material 11 and the trigger electrode 13, and the trigger electrode 13 may be attached to the cathode electrode 12 via an insulator. These anode electrode 23, cathode electrode 12, and trigger electrode 13 are preferably kept electrically insulated by the insulator 14 and an insulator. The insulator 14 and the insulator may be constructed integrally or separately.

A trigger power source consisting of a pulse transformer is connected between the cathode electrode 12 and the trigger electrode 13, and an arc power source 34 is connected between the cathode electrode 12 and the anode electrode 23. The arc power source 34 consists of a DC voltage source 32 and a capacitor unit 33. Both ends of the capacitor unit 33 are connected to the cathode electrode 12 and the anode electrode 23, respectively, and the capacitor unit 33 and the DC voltage source 32 are connected in parallel. has been done.
The DC power supplies 31 and 32 and the capacitor unit 33 are referred to as a power supply module 6.
In the coaxial vacuum arc evaporation source 5 , arc discharge occurs between the evaporation material 11 and the anode electrode 23 .

The capacitor unit 33 is one in which one or more capacitors (one capacitor is illustrated in FIG. 4) are connected, and the capacitance of one of the capacitors is, for example, 2200 μF (withstand voltage 160 V). The DC voltage source 32 allows charging at any time.

The trigger power supply 13 transforms the input 200 V μs pulse voltage to about 17 times and outputs 3.4 kV (several μA) and positive polarity.
The arc power source 34 has a DC voltage source 32 with a predetermined voltage and a capacity of several amperes, and repeatedly charges and discharges the capacitor unit 33 from this DC voltage source.
Here, the DC power supply voltage Va of the DC power supply 32, the capacitor capacity C of the capacitor unit 33, the number N of shots to emit the vapor deposition material 11, and the frequency (period of repeating discharge) F depend on the type of the vapor deposition material 11 and the combination thereof. Selected.

The positive output terminal of the trigger power supply 32 is connected to the trigger electrode 13, and the negative terminal is connected to the same potential as the negative output terminal of the DC voltage source 32 of the arc power supply 34, and is connected to the cathode electrode 12. A positive terminal of the DC voltage source 32 of the arc power source 34 is grounded to the ground potential and connected to the anode electrode 23 . Both terminals of the capacitor unit 33 are connected between a positive terminal and a negative terminal of the DC voltage source 32.

In FIG. 4, the controller 18 is connected to a trigger power supply 32, and when the switch of the controller 18 is turned on and a signal is input to the trigger power supply 32 connected to the controller 18, a high voltage is output from the trigger power supply 32. It is configured as follows. Further, it is preferable that the controller 18 be connected to the CPU 19 and configured such that each controller can be operated by a signal (external signal) from the CPU.

A gas introduction system 16 and a vacuum exhaust system 9 are connected to the wall of the vacuum chamber 2 . This gas introduction system 16 includes a valve 61, a mass flow controller 62, a valve 63, and an oxygen gas cylinder 64 connected in this order through metal piping. This oxygen gas is introduced to oxidize the vapor deposition material.
The vacuum evacuation system 9 includes a valve 54, a turbo molecular pump 51, a valve 52, and a rotary pump 53 connected in this order with metal vacuum piping, and can evacuate the inside of the vacuum chamber 2 to preferably 0.1 to 1 Pa. It is configured as follows.
Further, the inside of the vacuum chamber 2 is preferably maintained at a temperature of 20 to 100°C.

Further, as described above, the nanostructure manufacturing apparatus 1 operates to set the DC power supply voltage Va of the DC power supply 32 so that the average particle diameter of the nano-sized particles forming the nanostructure (composite) is 5 to 30 nm. The capacitor capacity C of the capacitor unit 33, the number n of shots to emit the vapor deposition material 11, and the frequency (period of repeating discharge) F are determined.

The vapor deposition state was confirmed by the following method. Confirmed using a transmission electron microscope and XRD. Transmission electron microscopy confirmed that the nanoparticles were spherical.

Further, the discharge voltage applied to the anode electrode 23 is set to be 70V or more and 1000V or less.
This is because if the discharge voltage is less than 70V, the plasma drifts forward at a slow speed (10 km/s or less), and if it exceeds 1000V, discharge will occur between the cathode and the anode, causing problems.

The capacitor capacity of the capacitor unit 33 for arc discharge between the anode electrode 23 and the vapor deposition material is 300 μF or more. This is because if the capacitor capacitance is less than 300 μF, nano-sized particles cannot be formed, and although atoms fly out, they cannot be aggregated.

FIG. 5 is a diagram for explaining a nanostructure manufacturing apparatus 1 used for manufacturing nanostructures according to the first and second embodiments of the present invention.
As shown in FIG. 5, two evaporation materials 11 are prepared: a first evaporation material 11 of Si (Si) and a second evaporation material 11 of Li (Li).
Additionally, a first coaxial vacuum arc evaporation source 5 (Si) and a first power supply module 6 (Si) are provided for depositing the first evaporation material 11 (Si) and emitting it toward the surface of the object 10 to be evaporated. ), a second coaxial vacuum arc evaporation source 5 (Li) for evaporating the second evaporation material 11 (Li) and emitting it toward the surface of the object 10 to be evaporated, and a second power supply module 6 ( Li).
The basic structures of the first coaxial vacuum arc evaporation source 5 (Si) and the second evaporation material 11 (Li) are the same as the coaxial vacuum arc evaporation source 5.
Further, the basic structures of the first power supply module 6 (Si) and the second power supply module 6 (Li) are the same as the power supply module 6.
This is the same as the coaxial vacuum arc evaporation source 5.
Further, a first cathode electrode 12 (Si) is provided coaxially within the first anode electrode 23 (Si) and spaced a certain distance from the wall surface of the first anode electrode 23 (Si). ing.
A second cathode electrode 12 (Li) is provided coaxially within the second anode electrode 23 (Li) and spaced a certain distance from the wall surface of the second anode electrode 23 (Li). .

The nano-sized particle forming step in the nanostructure manufacturing method using the nanostructure manufacturing apparatus 1 will be described below.
First, the inside of the vacuum chamber 2 is made into a high vacuum atmosphere. Next, a DC voltage is applied to the anode electrode 23 and the cathode electrode 12 by the arc power supply 32 . In this state, the trigger power supply 31 is activated and a pulse voltage is applied to the trigger electrode 13.
Then, by applying voltage between the surface of the vapor deposition material 11 and the surface of the trigger electrode 13 through a distance equivalent to the thickness of the cylindrical portion of the insulator 14 (approximately 1 mm), a trigger discharge is generated on the surface of the insulator 14. Creeping discharge occurs. This trigger discharge evaporates constituent substances from the surface of the vapor deposition material 11, generating vapor, ions, electrons, and the like. Further, electrons are generated from the joint between the vapor deposition material 11 and the insulator 14.

When the pressure inside the anode electrode 23 increases due to these vapors, ions, electrons, etc. and the dielectric strength between the anode electrode 23 and the vapor deposition material 11 decreases, the electric charge charged in the capacitor unit 33 causes the vapor deposition material 11 to Arc discharge occurs between the anode electrode 23 and the anode electrode 23.
Arc discharge is not a continuous discharge, but a pulsed discharge, and is performed by adjusting the number of occurrences and the interval.

Due to this arc discharge, a large amount of current flows into the vapor deposition material 11, and when the vapor deposition material 11 evaporates due to Joule heat, metal ions, which are positively charged fine particles, flow from the side of the vapor deposition material 11 toward the anode electrode 23. released in large quantities.
A magnetic field is formed within the anode electrode 23 by the arc current generated by such arc discharge. The magnetic field exerts a force to push positively charged particles toward the opening of the anode electrode 23, so the ions emitted toward the anode electrode 23 are emitted into the vacuum chamber 2, holding the material to be deposited. It is injected toward the surface of the object to be evaporated 10 held on the substrate 8 of the section 4 . Then, a synthetic film (nanostructure) made of nano-sized particles is formed on the surface of the deposition object 10.

In the nanostructure manufacturing apparatus 1, the metal that is the evaporation material 11 of the coaxial vacuum arc evaporation source 5 becomes plasma, collides with the object to be evaporated 10 at room temperature and normal pressure, and aggregates to form a synthetic film ( nanostructures) are obtained.

FIG. 6 is a diagram for explaining conditions for forming a synthetic film on the deposition target 10 using the nanostructure manufacturing apparatus 1.
In the table shown in FIG. 6, "nanostructure" indicates a synthetic film formed on the deposition target 10.
Further, for each nanostructure, the set values of the above-mentioned evaporation material 11, number of shots N, DC power supply voltage Va, capacitor capacity C, and frequency F set in the nanostructure manufacturing apparatus 1 are described.

In FIG. 6, when there are two evaporation materials 11, a plurality of targets are used, and the nanostructure manufacturing apparatus 1 using a plurality of coaxial vacuum arc evaporation sources 5 shown in FIG. 1 is used.
In this embodiment, since the APD method is used as described above, large ion energy is released all at once upon reaching the deposition target 10, thereby suppressing crystal growth and obtaining nano-sized particles. By forming a film using a plurality of vapor deposition materials 11 (targets), a nanostructure consisting of multiple phases was successfully synthesized.

Further, under the conditions shown in FIG. 6, the pressure inside the vacuum chamber 2 is 0.9 Pa when the nanostructure is LiZrOx, and is 3×10 ⁻⁴ Pa in other cases. Since both Li and Si tend to form oxides, it was confirmed that oxidation proceeds to some extent even at this level of oxygen pressure.

By performing vapor deposition by the APD method using the above-described nanostructure manufacturing apparatus 1, a nanostructure (nanoparticle film) containing nano-sized particles having an average particle size of 5 to 30 nm can be obtained. A smooth film densely packed with nano-sized particles of 5 to 30 nm is formed in the nanostructure.

A structural metal or metal oxide can be obtained by using a metal conductor/high melting point material such as Zr, Li, Si, Cu, Nb, or a combination of a high melting point/low melting point material as the vapor deposition material 11, for example.

Even when two or more types of targets were used as the vapor deposition material 11, it was confirmed that particles of several tens of nanometers were uniformly dispersed without agglomeration.

FIG. 7 is a TEM diagram for explaining the state of a nanostructure film obtained by using Si as the vapor deposition material 11 by the APD method of the embodiment of the present invention.
FIG. 8 is a TEM diagram for explaining the state of a nanostructure film obtained by using Si and Li as the vapor deposition material 11 by the APD method of the embodiment of the present invention.

From the viewpoint of forming a film made of nanoparticles, the nanostructure film obtained by the APD method of this embodiment has more cracks on the surface than the film obtained by the sputtering method, as shown in FIGS. 7 and 8. The sputtering method shown in FIG. 9 is more uniform than the sputtering method shown in FIG.
The image in FIG. 9 is taken from "JP Maranchi, AF Hepp and PN Kumta, Electrochemical and Solid-State Letters, 2003, 6, A198-A201."
The film thickness of the nanostructure made of Si--O--C shown in FIG. 7 is 60 nm. Further, the film thickness of the nanostructure made of Li-Si-OC shown in FIG. 8 is 100 nm.

In the nanostructure manufacturing apparatus 1, an oxide is obtained by the deposition target 10 taking in oxygen from within the vacuum chamber 2 or from the deposition target 10 (substrate material).
In the case of multiple layers, specific elements are selectively oxidized by oxygen pressure control. This results in a composite metal/oxide composite.

In addition, a lithium ion battery electrode consisting of Si-O-C, Li-Si-O-C, and Si-Cu-O-C can be produced using the nanostructure obtained using the nanostructure manufacturing apparatus 1 described above. The materials were synthesized and evaluated. The film thickness at that time was 50 to 100 nm.
As a result of the evaluation, all of the lithium ion battery electrode materials exhibited a high charge/discharge activity of 3000 mAh/g.
Among them, Li-Si-O-C had a high cycle retention rate and maintained a high capacity for 300 cycles or more.

FIG. 10 is a diagram showing an SEM of the surface of a nanostructure containing Si, Si-O, and Si-C before charging and discharging.
FIG. 11 is an SEM view of the surface of the nanostructure containing Si, Si-O, and Si-C shown in FIG. 10 after 30 cycles of charging and discharging.
FIG. 12 is an SEM view of the surface of a nanostructure containing Si, Li-Si-O, and Li-C-O before charging and discharging.
FIG. 13 is a diagram showing an SEM of the surface of the nanostructure containing Si, Li-Si-O, and Li-C-O shown in FIG. 12 after 425 cycles of charging and discharging.

From the cross-sectional SEM observations shown in FIGS. 10 and 11, Si--O--C undergoes severe morphological changes as in the conventional case due to cycle deterioration.
On the other hand, as shown in FIGS. 12 and 13, Li-Si-O-C maintains the structure derived from the evaporation target 10 (substrate material), and the nano-sized particles into which the Li component is introduced do not change in shape. This results in excellent cycle characteristics.
Here, the Li/Si ratio y is preferably 1.6 or less. The ratio y is a molar ratio estimated from ICP composition analysis. Further, more preferably, the ratio y is 0.4 to 1.6. This allows for a well-balanced design of capacitor capacity, output, and cycle stability.
Li-Si-O-C nanostructures have superior cycling and power output compared to conventional Si polar films.

FIG. 14 is a diagram showing EDX mapping of the surface of a nanostructure composed of Si—O—C after 30 cycles of charging and discharging.
FIG. 15 is a diagram showing EDX mapping of the surface of a nanostructure composed of Li-Si-O-C after 425 cycles of charging and discharging.

In a nanostructure composed of Si-O-C, Si exists over the entire surface, cracks occur irregularly throughout the structure, Cu (current collector) is exposed, and eventually the Si becomes finer. was confirmed.
In addition, the nanostructure composed of Li-Si-O-C maintains an electrode morphology that reflects the morphology of Cu (current collector) even after long-term cycles, and Li-Si-O-C remains continuous. It is distributed in

FIG. 16 is an image diagram of charging and discharging when a nanostructure composed of Li-Si-O-C is used as a battery electrode.
As shown in Figure 16, when Li-Si-O, Si, and _SiO It prevents excessive expansion of Si by showing a role or a reversible electrochemical reaction. Long-term cycles are possible by suppressing the structural deterioration of Si as shown in Figure 41 due to excessive expansion.

The characteristics of the nanostructure of Example 1 described above will be explained below.
FIGS. 17 and 18 are diagrams for explaining atomic force microscope images of a nanostructure synthesized with 10,000 shots of Si.
FIG. 17 shows a case where synthesis is performed at an oxygen pressure of 3×10 ⁻⁴ Pa in the vacuum chamber 2, and FIG. 18 shows a case where synthesis is performed at an oxygen pressure of 5 Pa.
In both FIGS. 17 and 18, it can be seen that the particles are synthesized by depositing particles of 30 nm or less.

FIG. 19 is a diagram for explaining an atomic force microscope image of a nanostructure synthesized with a Li/Si ratio y=3.6 (Si: 6280 shots, Li: 620 shots).
Also in FIG. 19, it can be seen that the particles are synthesized by depositing particles of 30 nm or less.

In the embodiment described above, an example is illustrated in which the object to be evaporated 10 is placed on the substrate 8, but a single crystal or a foil may be used as the substrate (and the object to be evaporated) by vapor deposition.
The type of substrate (and object to be deposited) is not particularly limited as long as it is chemically stable for manufacturing nanostructures. Specifically, an oxide such as Al ₂ O ₃ or SrTiO ₃ or a metal plate such as Cu, Ti, Au, or Pt may be used.

FIG. 20 is a flowchart for explaining a method for manufacturing a nanostructure using the nanostructure manufacturing apparatus 1.
Each step will be explained below with reference to FIG.

Step ST1:
The substrate 8 on which the object to be evaporated 10 is placed is held by the evaporation material holding section 4 .
The timing of step ST1 is not particularly limited as long as it is before step ST3.

Step ST2:
Vapor deposition material 11 is installed.
The timing of step ST2 is not particularly limited as long as it is before step ST4.
When manufacturing the nanostructure of the first example, as shown in FIG. Installed as Li).

Step ST3:
The oxygen pressure within the vacuum chamber 2 is adjusted.
When manufacturing the nanostructure of the first example, the oxygen pressure in the vacuum chamber 2 shown in FIG. 5 is set to 3×10 ⁻⁴ to 5 Pa.

Step ST4:
The number of shots N, DC power supply voltage Va, capacitor capacity C, and frequency F are set.
The timing of these settings is not particularly limited as long as it is before step S4.
When manufacturing the nanostructure of the first example, the number of shots N (Si) by the first coaxial vacuum arc evaporation source 5 (Si) shown in FIG. The number of shots N (Li) by the evaporation source 5 (Li) is set to 200 to 4800, the first discharge voltage V (Si) is set to 100 to 200 V, and the second discharge voltage V (Li) is set to 100 to 150.
Further, other values are set as shown in FIG. By setting in this way, the nanostructure of the first example described above with excellent discharge characteristics was obtained.

Step ST5:
The material-to-deposit holding section 4 is rotated.

Step ST6:
The nano-sized particle forming step described above is carried out.
That is, the vapor deposition material 11 is irradiated onto the vapor deposited object 10 from an arc plasma deposition source, and nano-sized particles having an average particle size of 5 to 30 nm are contained in the vapor deposited object 10 to form a nanostructure. Manufacture.

The invention is not limited to the embodiments described above.
That is, those skilled in the art may make various changes, combinations, subcombinations, and substitutions with respect to the components of the above-described embodiments within the technical scope of the present invention or its equivalent scope.
For example, in the above-described embodiment, the nanostructure is formed using the APD method, but it may also be formed using a powder process.

The present invention is applicable to a wide range of technical fields, including the automobile industry, energy industry, home appliance industry, and chemical industry, which handle lithium ion batteries and the like.

1... Metal nanoparticle production device 2... Vacuum chamber 4... Deposited material holding section 5, 5 (Li), 5 (Si)... Coaxial vacuum arc evaporation source 6, 6 (Li), 6 (Si)... Power supply module (power supply)
8... Substrate 10... Deposited objects 11, 11 (Li), 11 (Si)... Vapor deposition material 12... Cathode electrode 13... Trigger electrode 15... Insulator 18... Controller 23... Anode electrode 31... Trigger power source 32... DC voltage source 33...Capacitor unit

Claims (8)

A vapor deposition material of Li and Si metal atoms is irradiated onto a material to be vaporized from an arc plasma deposition source, and nano-sized particles of the vapor deposition material having an average particle size of 5 to 30 nm are deposited on the material to be vaporized, Si, SiOx , A method for producing a structure, comprising a nanostructure forming step of forming a nanostructure which is a composite film made of Li-Si-O and Li ₂ CO ₃ . Before the nanostructure forming step, a deposition material installation step of installing the deposition material in a vacuum chamber;
The nanostructure manufacturing method according to claim 1, further comprising a vapor deposition material installation step of installing the vapor deposition material before the nanostructure formation step. The arc plasma deposition source is configured by coaxially disposing a cylindrical anode electrode and a cylindrical cathode electrode to which the evaporation material is electrically connected inside the anode electrode,
The nanostructure manufacturing method according to claim 1 or 2, wherein the discharge voltage applied to the anode electrode is 70 V or more and 1000 V or less. 4. The nanostructure manufacturing method according to claim 3, further comprising a setting step of setting the number of shots N of the vapor deposition material, the discharge voltage Va, the capacitor capacity C, and the frequency F before the nanostructure forming step. 5. The nanostructure manufacturing method according to claim 1, wherein in the nanostructure forming step, the vapor deposition material is irradiated onto the vapor deposition material while rotating the vapor deposition material. a holding means installed in the vacuum chamber and holding a material to be deposited;
an arc plasma evaporation source that irradiates the material to be evaporated with a evaporation material of metal atoms;
irradiating the vapor deposition material of metal atoms of Li and Si from the arc plasma deposition source onto the material to be vapor deposited, and depositing nano-sized particles of the vapor deposition material on the material to be vapor deposited, Si, SiOx, Li-Si A nanostructure manufacturing device that forms a nanostructure that is a composite film consisting of -O and Li ₂ CO ₃ . a vacuum chamber;
a material to be deposited installed in the vacuum chamber;
a first vapor deposition material and a second vapor deposition material installed in the vacuum chamber;
a first anode electrode that causes a first arc plasma discharge between the first vapor deposition material;
a second anode electrode that causes a second arc plasma discharge between the second vapor deposition material;
a first cathode electrode provided coaxially within the first anode electrode and spaced a certain distance from a wall surface of the first anode electrode;
a second cathode electrode coaxially provided inside the second anode electrode and spaced a certain distance from the wall surface of the second anode electrode, the nanostructure manufacturing method using:
a deposition material installation step of installing the deposition material in the vacuum chamber;
a vapor deposition material installation step of installing Si as a first vapor deposition material and Li as a second vapor deposition material in the vacuum chamber;
an oxygen pressure adjustment step of adjusting the oxygen pressure in the vacuum chamber;
The number of shots of the first vapor deposition material N(1), the number of shots of the second vapor deposition material N(2), and a first anode electrode that causes a first arc plasma discharge between the first vapor deposition material and the first vapor deposition material. and a second discharge voltage V(2) to be applied to the second anode electrode to cause a second arc plasma discharge between the second vapor deposition material and the second vapor deposition material. a setting process to
Under the oxygen pressure adjusted in the oxygen pressure adjustment step and the conditions set in the setting step, the first vapor deposition material and the second vapor deposition material are irradiated onto the material to be vaporized by arc plasma discharge, and the average particle size is Nanosized particles of Si and Li with a diameter of 5 to 30 nm are deposited on the material to be deposited to satisfy the following condition (1), and a composite film consisting of Si, SiOx, Li-Si-O and Li ₂ CO ₃ is prepared. a nanostructure forming step of forming a nanostructure on the deposition material;
A method for producing a nanostructure.
Li/Si ratio y and O/Si ratio z are "0<y,z≦4"
...(1) In the oxygen pressure adjustment step, the oxygen pressure is set to 3×10 ⁻⁴ to 5 Pa,
The setting step includes:
The number of shots N(1) is 300 to 18,000, the number of shots N(2) is 200 to 4,800, the first discharge voltage V(1) is 100 to 200V, and the second discharge voltage V(2) is The nanostructure manufacturing method according to claim 7, wherein the nanostructure manufacturing method is set to 100 to 150.

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