WO2017195071A1 - Negative electrode to be used in power storage device, power storage device, and electrical device - Google Patents

Negative electrode to be used in power storage device, power storage device, and electrical device Download PDF

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Publication number
WO2017195071A1
WO2017195071A1 PCT/IB2017/052547 IB2017052547W WO2017195071A1 WO 2017195071 A1 WO2017195071 A1 WO 2017195071A1 IB 2017052547 W IB2017052547 W IB 2017052547W WO 2017195071 A1 WO2017195071 A1 WO 2017195071A1
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region
negative electrode
power storage
storage device
sample
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PCT/IB2017/052547
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French (fr)
Japanese (ja)
Inventor
石川純
門馬洋平
三上真弓
藤田未来
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株式会社半導体エネルギー研究所
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Priority to JP2016095791 priority
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Publication of WO2017195071A1 publication Critical patent/WO2017195071A1/en

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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors [EDLCs]; Processes specially adapted for the manufacture thereof or of parts thereof
    • H01G11/22Electrodes
    • H01G11/30Electrodes characterised by their materials
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of or comprising active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134Electrodes based on metals, Si or alloys
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of or comprising active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of or comprising active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/38Selection of substances as active materials, active masses, active liquids of elements or alloys
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01GCAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors [EDLCs]; Processes specially adapted for the manufacture thereof or of parts thereof
    • H01G11/22Electrodes
    • H01G11/30Electrodes characterised by their materials
    • H01G11/46Metal oxides, e.g. ruthenium oxide

Abstract

Provided are: a high-capacity power storage device; or a power storage device exhibiting excellent cycle properties; or a power storage device exhibiting high charge/discharge efficiency; or a power storage device which uses a low-resistance negative electrode. Thus, a negative electrode to be used in a power storage device, and equipped with multiple particulate composites, wherein the composites have a first region and a second region, the first region contains amorphous silicon, the second region contains crystalline silicide, the end section of the second region overlaps the first region, and the second region is contained within the first region.

Description

Negative electrode for power storage device, power storage device, and electric device

The present invention relates to an object, a method, or a manufacturing method. Or this invention relates to a process, a machine, a manufacture, or a composition (composition of matter). In particular, one embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to an electrode for a power storage device and a method for manufacturing the electrode.

In recent years, portable electronic devices such as mobile phones, smartphones, electronic books (electronic books), and portable game machines have become widespread. For this reason, a power storage device typified by a lithium ion secondary battery as a driving power source has been actively researched and developed. In addition, the importance of power storage devices is increasing in various applications, such as hybrid cars and electric cars attracting attention due to increasing interest in global environmental problems and petroleum resource problems.

Among power storage devices, lithium ion secondary batteries that are widely used due to their high energy density include a positive electrode containing an active material such as lithium cobaltate (LiCoO 2 ) and lithium iron phosphate (LiFePO 4 ), Consists of a negative electrode made of carbon material such as graphite that can be occluded and released, and an electrolytic solution in which an electrolyte made of a lithium salt such as LiBF 4 or LiPF 6 is dissolved in an organic solvent such as ethylene carbonate or diethyl carbonate. . Charging / discharging of a lithium ion secondary battery means that lithium ions in the lithium ion secondary battery move between the positive electrode and the negative electrode through the electrolytic solution, and lithium ions are inserted into or extracted from the positive electrode active material or the negative electrode active material. Is done.

On the other hand, lithium ion secondary batteries are widely used as drive power sources for portable electronic devices and electric vehicles, and there is an extremely strong demand for downsizing and large capacity of lithium ion secondary batteries.

A negative electrode used for a lithium ion secondary battery is manufactured by forming an active material on at least one surface of a current collector. Conventionally, graphite, which is a material capable of occluding and releasing ions serving as carriers (hereinafter referred to as carrier ions), has been used as the negative electrode active material. A negative electrode is produced by kneading graphite as a negative electrode active material, carbon black as a conductive additive, and resin as a binder to form a slurry, applying the slurry onto a current collector, and drying. It was. In place of carbon materials such as graphite used for conventional negative electrode active materials, development of forming electrodes using an alloy-based material such as silicon or tin is active.

When silicon, which is a material that reacts with and dealloys with lithium, instead of graphite, is used as the negative electrode active material, the capacity can be increased compared to carbon materials such as graphite. The theoretical capacity of the silicon negative electrode is dramatically large, 4200 mAh / g, compared with the theoretical capacity of 372 mAh / g of the carbon (graphite) negative electrode. Therefore, it is an optimal material in terms of increasing the capacity of the lithium ion secondary battery.

However, a material that is alloyed with lithium, such as silicon, has a large expansion and contraction that accompanies occlusion and release of carrier ions in a charge / discharge cycle when the amount of occlusion of carrier ions increases. When the conductive path is damaged, the capacity decreases with a charge / discharge cycle. Further, in some cases, silicon is deformed or collapsed, and it becomes difficult to maintain the function as the lithium ion secondary battery by peeling or pulverizing from the current collector.

In Patent Document 1, a silicon layer is formed over a current collector, and a conductive layer is provided over the silicon layer. Thereby, even if silicon expands and contracts repeatedly and current can be collected through the conductive layer even if the silicon layer is peeled off from the current collector, deterioration of battery characteristics is reduced. In addition, the use of a layer in which an impurity such as phosphorus or boron is added to a silicon layer is also disclosed as a conductive layer.

JP 2012-009429 A

An object of one embodiment of the present invention is to provide a power storage device with high capacity. Another object of one embodiment of the present invention is to provide a power storage device with excellent cycle characteristics. Another object of one embodiment of the present invention is to provide a power storage device with high charge and discharge efficiency. Another object of one embodiment of the present invention is to provide a novel power storage device or the like.

Note that the description of these issues does not disturb the existence of other issues. Note that one embodiment of the present invention does not have to solve all of these problems. Issues other than these will be apparent from the description of the specification, drawings, claims, etc., and other issues can be extracted from the descriptions of the specification, drawings, claims, etc. It is.

One embodiment of the present invention includes a large number of particulate composites, and the composite includes a first region and a second region, and the first region includes amorphous silicon, The second region includes crystalline silicide, and an end portion of the second region is a negative electrode for a power storage device that overlaps the first region.

One embodiment of the present invention includes a large number of particulate composites, and the composite includes a first region and a second region, and the first region includes amorphous silicon, The second region includes crystalline silicide, the second region has a region in contact with the first region at an end portion of the second region, and the second region is in the vicinity of the end portion of the second region. This region is a negative electrode for a power storage device in which the crystallinity decreases as the distance from the first region decreases.

In addition, the negative electrode for a power storage device described above in which the crystalline silicide includes any of titanium, tantalum, and tungsten is also an embodiment of the present invention.

The thickness of the second region is 1 nm or more and 50 nm or less, and the above negative electrode for a power storage device is also one embodiment of the present invention.

The above-described negative electrode for a power storage device, in which the atomic ratio of silicon to any one of titanium, tantalum, and tungsten is 2 times or more and 20 times or less is also an embodiment of the present invention.

Further, a power storage device including the above negative electrode for a power storage device is also one embodiment of the present invention.

In addition, an electrical device including the above power storage device is also one embodiment of the present invention.

According to one embodiment of the present invention, a power storage device with high capacity can be provided. According to one embodiment of the present invention, a power storage device with excellent cycle characteristics can be provided. Further, according to one embodiment of the present invention, a power storage device with high charge and discharge efficiency can be provided. According to one embodiment of the present invention, a power storage device using a negative electrode with low resistance can be provided. Alternatively, according to one embodiment of the present invention, a novel power storage device or the like can be provided.

Note that the description of these effects does not disturb the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. It should be noted that the effects other than these are naturally obvious from the description of the specification, drawings, claims, etc., and it is possible to extract the other effects from the descriptions of the specification, drawings, claims, etc. It is.

The figure explaining a negative electrode. The figure explaining the composite particle contained in a negative electrode active material layer. The figure explaining the composite particle contained in a negative electrode active material layer. The figure explaining a negative electrode. The figure explaining a coin-type storage battery. The figure explaining a cylindrical storage battery. The figure explaining a thin storage battery. The figure explaining the thin storage battery which has flexibility. The figure explaining a thin storage battery. The figure explaining a thin storage battery. FIG. 9 illustrates an example of a power storage device. FIG. 9 illustrates an example of a power storage device. FIG. 9 illustrates an example of a power storage device. FIG. 9 illustrates an example of a power storage device. FIG. 9 illustrates an example of a power storage device. 6A and 6B illustrate an electronic device including a power storage device. FIG. 11 illustrates an application mode of a power storage device. The SEM observation result and SEM-EDX analysis result of the sample A based on Example 1. FIG. The XRD spectrum of the sample A and literature value based on Example 1. FIG. The XRD spectrum of the sample B and literature value based on Example 1. FIG. The XRD spectrum of the sample C and literature value based on Example 1. FIG. The XRD spectrum of the sample D and literature value based on Example 1. FIG. The XRD spectrum of the sample E and literature value based on Example 1. FIG. Charging / discharging curve of each cell according to Example 1 The charging / discharging curve of each cell based on Example 1. FIG. The graph which shows transition of the capacity | capacitance maintenance rate of the low load amount cell based on Example 1. FIG. The graph which shows transition of the capacity | capacitance maintenance factor of the high load amount cell based on Example 1. FIG. The graph which shows transition of the capacity maintenance rate of each cell based on Example 2. FIG. 6 is a cross-sectional STEM image of Comparative Sample I according to Example 2. FIG. 6 is a cross-sectional STEM image of sample H according to Example 2. FIG. The cross-sectional TEM image and ED measurement result of the sample A based on Example 3. FIG. The cross-sectional TEM image and ED measurement result of the sample B based on Example 3. FIG. The cross-sectional TEM image and ED measurement result of the sample C based on Example 3. FIG. The cross-sectional TEM image and ED measurement result of the sample D based on Example 3. FIG. The cross-sectional TEM image and ED measurement result of the sample E based on Example 3. FIG.

Hereinafter, embodiments will be described with reference to the drawings. However, the embodiments can be implemented in many different modes, and it is easily understood by those skilled in the art that the modes and details can be variously changed without departing from the spirit and scope thereof. . Therefore, the present invention should not be construed as being limited to the description of the following embodiments.

(Embodiment 1)
In this embodiment, a negative electrode used for the power storage device according to one embodiment of the present invention will be described. A method for producing the negative electrode will be described.

[Negative electrode structure 1]
1A is an overhead view of the negative electrode, and FIG. 1B is an enlarged view of a cross section surrounded by a broken line in FIG. 1A. The negative electrode 100 has a structure in which a negative electrode active material layer 102 is provided in contact with the negative electrode current collector 101. In the figure, the negative electrode active material layer 102 is provided on both surfaces of the negative electrode current collector 101, but the negative electrode active material layer 102 may be provided only on one surface of the negative electrode current collector 101.

FIG. 1C is a cross-sectional view of the negative electrode active material layer 102 including the composite 103, the conductive additive 104, and the binder 105. The composite 103 is surrounded by a conductive additive 104 and a binder 105. Note that since the boundary between the conductive auxiliary agent 104 and the binder 105 is not clear, it is indicated by one hatching in the figure.

The negative electrode active material layer 102 has a large number of particulate composites. That is, the negative electrode for a power storage device of one embodiment of the present invention includes a composite. The composite has a first region containing amorphous silicon and a second region containing crystalline silicide. The first region of the composite functions as an active material. A specific configuration of the composite will be described later.

Note that the active material refers to a substance related to insertion and desorption of ions as carriers. At the time of manufacturing the negative electrode, which will be described later, a mixture containing an active material and a mixture of other materials such as a conductive additive, a binder, and a solvent is formed on the current collector as an active material layer. Therefore, an active material and an active material layer are distinguished.

The negative electrode current collector 101 is made of metal such as gold, platinum, zinc, iron, copper, titanium, tantalum, manganese, and alloys thereof (stainless steel, etc.), and has high conductivity, and carrier ions such as lithium ions and alloys. It is possible to use a material that does not change. Alternatively, a metal element that forms silicide by reacting with silicon may be used. Examples of metal elements that react with silicon to form silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, and the like. The negative electrode current collector 101 can have a foil shape, a plate shape (sheet shape), a net shape, a columnar shape, a coil shape, a punching metal shape, an expanded metal shape, or the like as appropriate. For example, the negative electrode current collector 101 may have a thickness of 5 μm to 30 μm, and more preferably a thickness of 8 μm to 15 μm. Note that, as an example, the negative electrode current collector 101 has a thickness of 5 μm to 30 μm, more preferably 8 μm to 15 μm over the entire region. Note that one embodiment of the present invention is not limited to this. For example, the negative electrode current collector 101 may have a region having a thickness of 5 μm or more and 30 μm or less, more desirably, a thickness of 8 μm or more and 15 μm or less, at least partially. Alternatively, the negative electrode current collector 101 preferably has a thickness of 5 μm or more and 30 μm or less, more preferably 8 μm or more and 15 μm or less in a region of 50% or more occupying the entire area of the negative electrode current collector 101. It is good to have.

As the negative electrode active material, a metal capable of performing a charge / discharge reaction by alloying with a carrier ion or a dealloying reaction and a compound thereof can be used. When the carrier ions are lithium ions, for example, Mg, Ca, Al, Si, Ge, Sn, Pb, As, Sb, Bi, Ag, Au, Zn, Cd, Hg, etc. can be used as the metal. . Such a metal has a larger capacity than graphite, and particularly Si (silicon) has a theoretical capacity of 4200 mAh / g, which is remarkably high. For this reason, it is preferable to use silicon for the negative electrode active material. Examples of the compound material used for the negative electrode active material include SiO, Mg 2 Si, Mg 2 Ge, SnO, SnO 2 , Mg 2 Sn, SnS 2 , V 2 Sn 3 , FeSn 2 , CoSn 2 , and Ni 3 Sn. 2 , Cu 6 Sn 5 , Ag 3 Sn, Ag 3 Sb, Ni 2 MnSb, CeSb 3 , LaSn 3 , La 3 Co 2 Sn 7 , CoSb 3 , InSb, SbSn and the like.

Further, as the negative electrode active material, titanium dioxide (TiO 2 ), lithium titanium oxide (Li 4 Ti 5 O 12 ), niobium pentoxide (Nb 2 O 5 ), tungsten oxide (WO 2 ), molybdenum oxide (MoO 2 ) Etc. can be used. Further, a lithium-graphite intercalation compound (Li x C 6 ) may be used as the negative electrode active material.

Further, as the anode active material, a nitride of lithium and a transition metal, Li 3 Li 3-x with N-type structure M x N (M = Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N 3 shows a large charge / discharge capacity (900 mAh / g) and is preferable.

When a nitride of lithium and a transition metal is used, lithium ions are included in the negative electrode active material. Therefore, it can be combined with a material such as V 2 O 5 or Cr 3 O 8 that does not include lithium ions as the positive electrode active material. Even when a material containing lithium ions is used for the positive electrode active material, lithium and transition metal nitrides can be used as the negative electrode active material by desorbing lithium ions contained in the positive electrode active material in advance. .

The negative electrode for a power storage device of one embodiment of the present invention uses silicon as a negative electrode active material. As the silicon, amorphous silicon, microcrystalline silicon, polycrystalline silicon, or a combination thereof can be used. In general, the higher the crystallinity, the higher the electrical conductivity of silicon. Therefore, silicon with high crystallinity can be used as an electrode with high conductivity in a power storage device. On the other hand, when silicon is amorphous, more carrier ions such as lithium ions can be occluded than crystalline silicon, so that the discharge capacity can be increased.

In the negative electrode for a power storage device of one embodiment of the present invention, the second region included in the composite includes silicide. When the composite has silicide, the conductivity of the negative electrode active material layer can be increased. Note that in the case where the conductivity of the negative electrode active material layer can be sufficiently increased when the composite includes silicide, the silicon contained in the first region of the composite is preferably amorphous silicon.

Further, by adding impurities to increase the conductivity of silicon, nonuniformity of battery reaction in the electrode can be reduced. Examples of the impurity to be added include phosphorus (P) and arsenic (As) as impurities imparting n-type, and boron (B), aluminum (Al), and gallium as impurities imparting p-type. (Ga) etc. are mentioned. For example, the resistivity of silicon is preferably 1 × 10 −4 [Ω · cm] to 50 [Ω · cm], more preferably 1 × 10 −3 [Ω · cm] to 20 [Ω · cm. It is the following.

The composite contains crystalline silicide in the second region. Crystalline silicide contains silicon and a metal element. As the metal element contained in the crystalline silicide, titanium, tantalum, and tungsten are preferable. When the composite has the second region, the stress generated by the volume change accompanying the occlusion and release of lithium ions in the first region can be relieved, and cracks generated in the negative electrode active material layer can be suppressed. In addition, since the above metal element has high lithium ion permeability, even when the composite has the second region, insertion and extraction of lithium ions in the first region can be performed smoothly.

Note that the composite may include crystalline silicon such as polycrystalline silicon or microcrystalline silicon in the first region. In addition, the composite may include low-crystallinity, that is, amorphous silicide in the second region.

Further, the negative electrode active material layer 102 has a conductive auxiliary agent 104. When the negative electrode active material layer 102 includes a conductive additive, the electron conductivity of the negative electrode active material layer 102 is improved. As the conductive aid, various conductive aids such as acetylene black particles, ketjen black (registered trademark) particles, carbon particles such as carbon nanofibers, graphene, and the like can be used.

In addition, the negative electrode active material layer 102 includes a binder 105. By using the binder (binder), the binding properties of the negative electrode active material and the conductive auxiliary agent and the binding properties of the negative electrode active material and the current collector can be improved. In addition to typical polyvinylidene fluoride (PVDF), binders include polyimide, polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene polymer, butadiene rubber, styrene-butadiene rubber, butyl rubber, acrylonitrile-butadiene rubber, and fluororubber. Polyvinyl acetate, polymethyl methacrylate, polyethylene, polypropylene, nitrocellulose and the like can be used. In addition, a compound mainly composed of polyacrylic acid or polyglutamic acid (polymethyl acrylate, sodium polyacrylate, or the like) may be used as the binder. In particular, when silicon or the like that has a significant volume change due to charge / discharge is used as the negative electrode active material, by using polyimide having excellent binding properties, the negative electrode active materials, the negative electrode active material and the conductive auxiliary agent, The binding property of the current collector and each of the graphene and the current collector can be improved. Thereby, exfoliation and pulverization of a negative electrode active material can be controlled, and good charge / discharge cycle characteristics can be obtained.

Next, a more detailed cross-sectional configuration example of the composite 103 will be described with reference to FIG.

<Detailed cross-sectional configuration example 1 of composite particles>
FIG. 2A is an example of an enlarged cross-sectional view of a region 106 that is part of the complex 103 illustrated in FIG.

The complex 103 includes a first region 111 and a second region 112 (see FIG. 2A). The first region 111 includes amorphous silicon, and the second region 112 includes crystalline silicide. For example, it can be said that the first region 111 is a region having lower crystallinity than the second region 112, and the second region 112 is a region having higher crystallinity than the first region 111.

The first region 111 functions as a negative electrode active material. Thus, the first region 111 expands or contracts with charge / discharge of the power storage device. By providing the second region 112 in close contact with the first region 111, it is possible to suppress cracks that are generated when the first region 111 repeatedly expands or contracts.

The second region 112 is formed in a shape close to a circle, an ellipse, a polygon, or a closed curve according to them in a cross-sectional view of an arbitrary cut surface. Therefore, the second region 112 has an island shape, and the second region 112 has a structure enclosed in the first region 111.

It may be difficult to observe a clear boundary between the first region 111 and the second region 112. For example, it can be said that the end of the second region 112 overlaps with the first region 111. Alternatively, the second region 112 has a region in contact with the first region 111 at an end thereof, and the second region 112 has a crystallinity as the distance from the first region 111 decreases in the vicinity of the end portion. It can be said that it decreases. By setting it as such a structure, since the adhesiveness of the 1st area | region 111 and the 2nd area | region 112 improves, the effect which suppresses said crack can be heightened. In addition, since the surface area of the first region 111 in contact with the electrolytic solution in the power storage device can be reduced, decomposition of the electrolytic solution due to the battery reaction of the negative electrode active material can be reduced. Further, peeling of part of the negative electrode active material from the surface of the first region 111 can be reduced.

The second area 112 is irregularly distributed in the first area 111. Therefore, the plurality of second regions 112 may be connected (see FIG. 2B). That is, in the cross-sectional view of a certain cut surface, the second region 112 may have a shape in which a plurality of closed curves are connected at the end. In addition, the plurality of second regions 112 may be three-dimensionally connected, so that the first region 111 may be included in the second region 112. That is, the complex 103 may have the first region 111 included in the second region 112.

Alternatively, in the complex 103, the first region 111 and the second region 112 may be unevenly distributed in a patch shape (also referred to as a mosaic shape).

The size of one second region 112 can be adjusted by the manufacturing conditions or composition of the complex 103. The magnitude | size of the 2nd area | region 112 can be evaluated with the high-resolution TEM image which can be acquired with a transmission electron microscope (TEM: Transmission Electron Microscope). For example, the thickness (also referred to as a diameter) of the second region 112 may be observed from 1 nm to 50 nm in the TEM image. Note that the thickness of the second region 112 is preferably 5 nm to 20 nm.

Further, the ratio of the second regions 112 interspersed can be adjusted as appropriate depending on the manufacturing conditions or composition of the composite 103. When the ratio of the second region 112 to the first region 111 is increased, the cycle characteristics of the power storage device are improved, while the capacity of the power storage device is decreased. Therefore, the ratio of the second region 112 is preferably determined in accordance with specifications required for the power storage device.

Note that when the size of the second region 112 is sufficiently smaller than the size of the composite 103 (for example, the size of the composite 103 is 20 times or more the size of the second region 112), SEM-EDX or the like In this elemental analysis, silicon and metal elements constituting silicide may be observed to be distributed substantially uniformly in the composite 103. That is, the first region 111 and the second region 112 are irregularly distributed in the complex 103 when viewed microscopically, but may exist so as to be distributed substantially uniformly when viewed macroscopically. is there.

<Detailed cross-sectional configuration example 2 of composite particle>
FIG. 3 is an example of an enlarged cross-sectional view of a region 106 which is a part of the complex 103 illustrated in FIG. 1C, which is different from FIGS. 2A and 2B. 2A and 2B, the description of FIGS. 2A and 2B can be referred to.

The composite 103 has a first region 111, a second region 112, a third region 113, and a fourth region 114 (see FIG. 3). In FIG. 3, the second region 112, the third region 113, and the fourth region 114 are distinguished by the color density of the region. When the colors of the respective regions are arranged in order of darkness, a second region 112, a third region 113, and a fourth region 114 are obtained. Note that the color density of each region is for convenience.

The first region 111 includes amorphous silicon, the second region 112 includes crystalline silicide, the third region 113 includes polycrystalline silicon and / or microcrystalline silicon, and the fourth region 114 includes Contains amorphous silicide. For example, it can be said that the first region 111 is a region having lower crystallinity than the third region 113 and the second region 112 is a region having higher crystallinity than the fourth region 114.

The first region 111 and the third region 113 function as a negative electrode active material.

The second region 112, the third region 113, and the fourth region 114 are formed in a shape close to a circle, an ellipse, a polygon, or a closed curve according to them in a cross-sectional view of an arbitrary cut surface. Therefore, the second region 112, the third region 113, and the fourth region 114 are island-shaped, and the second region 112, the third region 113, and the fourth region 114 are included in the first region 111. Take the structure.

It may be difficult to observe a clear boundary between the first region 111, the second region 112, the third region 113, and the fourth region 114.

Since the second region 112, the third region 113, and the fourth region 114 are unevenly distributed in the first region 111, the second region 112, the third region 113, the fourth region 114 Each of the areas 114 may be connected (see FIG. 3). For example, the plurality of second regions 112, the third region or / and the fourth region 114 are three-dimensionally connected, so that the first region 111 becomes the second region 112, the third region 113, and / or There is a case where it is included in the fourth region 114.

Alternatively, in the complex 103, the first region 111, the second region 112, the third region 113, and the fourth region 114 may be unevenly distributed in a patch shape (also referred to as a mosaic shape). .

In addition, the complex 103 may not have the third region 113 or the fourth region 114.

The size of one second region 112, third region 113, or fourth region 114 can be adjusted depending on the manufacturing conditions or composition of the composite 103.

The ratio of the second region 112, the third region 113, and the fourth region 114 interspersed can be adjusted as appropriate depending on the manufacturing conditions or composition of the composite 103. As the ratio of the second region 112 and the fourth region 114 to the first region 111 and the third region 113 increases, the cycle characteristics of the power storage device improve, while the capacity of the power storage device decreases. Therefore, the ratio of the second region 112 and the fourth region 114 is preferably determined in accordance with specifications required for the power storage device.

The above negative electrode can be used for the power storage device which is one embodiment of the present invention.

[Method of Manufacturing Negative Electrode Structure 1]
In this embodiment mode, silicon is used as an active material included in the composite 103, and titanium is used as a metal material for forming a silicide included in the composite 103. Below, the manufacturing method of the negative electrode 100 mentioned above is demonstrated.

First, granular silicon and granular titanium are prepared, weighed and mechanically kneaded. Weighing is performed so that the amount of silicon is larger (for example, the silicon is in a molar ratio of 2 to 20 times that of titanium). Specifically, as mechanical kneading, each material weighed and a plurality of metal balls are put in a metal container, and the container is rotated. The amount of balls is, for example, 5 times or more the total weight of each material. By adjusting the number of rotations of the container, the number of balls, the weight of the balls, the processing time of mechanical kneading, etc., the composite 103 having an appropriate particle size can be obtained.

Here, the particle size of the composite will be described. When the composite particles are larger than the conductive auxiliary agent, it is difficult to mix uniformly with the conductive auxiliary agent, and a good conductive path cannot be formed. In addition, when the particle size is large, the surface area is small with respect to volume expansion, so that the stress generated on the surface is large, and cracks and the like are likely to occur in the particles. On the other hand, when the particle size of the composite is too small, the surface area of the composite increases and the decomposition reaction of the electrolytic solution increases, so that the charge / discharge efficiency decreases and the capacity also decreases. Therefore, the particle size of the composite has a certain optimum value. For example, the composite preferably has a particle size of 0.01 μm to 30 μm, more preferably 0.1 μm to 20 μm, and still more preferably 0.5 μm to 5 μm.

The silicon prepared for obtaining the composite having the above particle diameter can be obtained by pulverizing non-granular silicon such as a silicon wafer. Alternatively, silicon having a large particle diameter may be pulverized to obtain silicon having a desired particle diameter. Examples of the pulverization method include pulverization using a mortar and pulverization using a ball mill. Further, after pulverization using a mortar in advance, pulverization may be performed using a ball mill. Here, as an example, the case of ball mill processing will be described. A solvent is added to the weighed raw material or materials and the mixture is rotated using a metal or ceramic ball. By performing the ball mill treatment, the raw materials can be made fine at the same time as the raw materials are mixed, and the electrode material after production can be made fine. Further, the raw materials can be uniformly mixed by performing the ball mill treatment.

<Conductive aid, particulate composite, and binder are added to a solvent and mixed. These mixing ratios may be appropriately adjusted according to desired battery characteristics.

As the solvent, a liquid in which the raw material is not dissolved and the raw material is dispersed in the solvent can be used. Further, the solvent is preferably a polar solvent, for example, water, methanol, ethanol, acetone, tetrahydrofuran (THF), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). Any one kind or two or more kinds of mixed liquids can be used.

Also, a binder having high heat resistance, such as polyimide, is used as the binder. However, the substance mixed in the mixing step is a polyimide precursor, and the precursor is imidized in the subsequent heating step to become polyimide.

As a method of mixing the above-mentioned compounds, for example, a kneader may be used. The binder, the composite and the solvent are combined and stirred using a kneader to prepare a slurry (mixture).

Next, a slurry is applied onto the negative electrode current collector 101, and the negative electrode current collector coated with the slurry is dried to remove the solvent. The drying step may be performed, for example, by holding in a dry atmosphere for about 1 hour at room temperature or 50 ° C. Note that when the solvent can be removed by a subsequent heating step, the drying step is not necessarily performed.

Next, the negative electrode current collector coated with the slurry is heated. The heating temperature is 200 ° C. or more and 500 ° C. or less, preferably 300 ° C. or more and 400 ° C. or less, and this is performed for 3 hours or more and 7 hours or less, preferably about 5 hours. The slurry is baked by the heating, and the polyimide precursor is imidized to become polyimide.

In the present embodiment, the heating step for baking the slurry is performed at a temperature at which the binder is not decomposed, for example, a temperature of 300 ° C. or higher and 400 ° C. or lower. Thereby, decomposition | disassembly of a binder can be prevented and the fall of the reliability of an electrical storage apparatus can be prevented.

Through the manufacturing process as described above, the negative electrode 100 having the negative electrode active material layer 102 on the negative electrode current collector 101 can be manufactured.

[Negative electrode structure 2]
Next, a negative electrode current collector used as a negative electrode of a power storage device, and a negative electrode active material layer including a graphene and a binder (also referred to as a binder) in combination with a particulate composite on the negative electrode current collector explain.

Graphene has a function as a conductive aid that forms an electron conduction path between the composite and the current collector. In this specification, graphene includes single-layer graphene or multilayer graphene of two to 100 layers. Single-layer graphene refers to a sheet of one atomic layer of carbon molecules having a π bond. When this graphene is formed by reducing graphene oxide, all oxygen contained in the graphene oxide is not desorbed, and some oxygen remains in the graphene. When oxygen is contained in graphene, the proportion of oxygen is, for example, 2 atomic percent to 20 atomic percent, preferably 3 atomic percent to 15 atomic percent of the entire graphene, as measured by XPS (X-ray photoelectron spectroscopy). It is as follows. Note that the graphene oxide refers to a compound in which the graphene is oxidized.

Moreover, the materials described in the binder described above can be used for the binder. In particular, when silicon or the like whose volume changes due to charging / discharging is used as the negative electrode active material constituting the composite, by using polyimide having excellent binding properties, the particulate composites can be combined with each other. And graphene, particulate composites and current collectors, and graphene and current collectors can be improved in binding properties. Thereby, exfoliation and pulverization of the composite can be suppressed and good charge / discharge cycle characteristics can be obtained.

As described above, when the negative electrode active material layer having a particulate composite, graphene, and a binder is used, the sheet-like graphene is two-dimensionally contacted so as to enclose the particulate alloy-based material, and the graphenes are further in contact with each other. Since the two-dimensional contact with each other overlaps, a huge network of three-dimensional electron conduction paths is constructed in the negative electrode active material layer. For these reasons, when using particulate acetylene black or ketjen black (registered trademark), which is generally used as a conductive additive, it is electrically point contact, but has high electronic conductivity. A negative electrode active material layer can be formed.

Further, when graphene is bonded to each other, network graphene (hereinafter referred to as graphene net) can be formed. In the case where the composite is covered with graphene net, the graphene net can also function as a binder for binding particles. Therefore, since the amount of the binder can be reduced or not used, the ratio of the composite to the electrode volume and the electrode weight can be improved. That is, the capacity of the power storage device can be increased.

4A is an overhead view of the negative electrode, and FIG. 4B is an enlarged view of a cross section surrounded by a broken line in FIG. 4A. The negative electrode 200 has a structure in which a negative electrode active material layer 202 is provided on a negative electrode current collector 201. In the figure, the negative electrode active material layer 202 is provided on both surfaces of the negative electrode current collector 201, but the negative electrode active material layer 202 may be provided only on one surface of the negative electrode current collector 201.

As the negative electrode current collector 201, the current collector shown as the negative electrode current collector 101 can be used.

FIG. 4C is a top view of the negative electrode active material layer 202 including the composite 103, a sheet-like graphene 204 covering the plurality of composites 103, and a binder (not shown). Different graphenes 204 cover the surfaces of the plurality of composites 103. In addition, the composite 103 may be exposed in part rather than being entirely covered with the graphene 204.

Graphene 204 is a thin film having a thickness of a single layer or multiple layers of carbon molecules. Since the plurality of graphenes 204 are formed so as to cover or cover the plurality of granular composites 103 or to be adhered to the surface of the plurality of granular composites 103, they are in surface contact with each other. The graphenes 204 are in surface contact with each other, so that a plurality of graphenes 204 form a three-dimensional electrical conduction network.

This is because, as will be described later, graphene oxide having extremely high dispersibility in a polar solvent is used for forming the graphene 204. In order to volatilize and remove the solvent from the dispersion medium containing the uniformly dispersed graphene oxide and reduce the graphene oxide to graphene, the graphene 204 remaining in the negative electrode active material layer 202 partially overlaps and is in surface contact with each other. The electric conduction path is formed by being dispersed.

Therefore, unlike conventional granular conductive aids such as acetylene black that are in point contact with the active material, graphene 204 enables surface contact with a low contact resistance, so that the amount of conductive aid is not increased. In addition, electrical conductivity between the granular composite 103 and the graphene 204 can be improved. Therefore, the ratio of the composite 103 in the negative electrode active material layer 202 can be increased. Thereby, the capacity | capacitance of an electrical storage apparatus can be increased. For example, the weight of the graphene 204 used for the negative electrode active material layer 202 is preferably 30% or less, more preferably 15% or less, and further preferably 3% or less of the weight of the composite 103. Note that the weight of graphene is almost halved after reduction of graphene oxide.

As described above, various conductive assistants such as acetylene black particles, ketjen black particles, and carbon particles such as carbon nanofibers in addition to graphene are used as conductive aids for improving the characteristics of the electron conduction path in the negative electrode active material layer 202. An agent may be contained.

FIG. 4D is a cross-sectional view of part of the negative electrode active material layer 202. The composite 103 and the graphene 204 covering the composite 103 are provided. The graphene 204 is observed as a line in the cross-sectional view. The plurality of composites 103 are provided so as to be sandwiched between the same graphene 204 or the plurality of graphenes 204. Note that the graphene 204 has a bag shape and may contain a plurality of composites 103. In some cases, the composite 103 is exposed without being covered with the graphene 204.

Graphene 204 forms a three-dimensional network. Therefore, in addition to functioning as a conductive additive, the graphene network has a function of holding the complex 103 capable of occluding and releasing carrier ions. For this reason, it can also serve as a binder. Therefore, the amount of the binder used can be reduced, the ratio of the composite 103 per negative electrode active material layer 202 can be increased, and the discharge capacity of the power storage device can be increased.

Further, in the composite 103 whose volume expands due to occlusion of carrier ions, the negative electrode active material layer 202 becomes brittle due to charge and discharge, and part of the negative electrode active material layer 202 may collapse. When a part of the negative electrode active material layer 202 collapses, the reliability of the power storage device decreases. However, even if the volume of the composite 103 increases or decreases due to charge and discharge, the graphene 204 covers the periphery, so that the graphene 204 can prevent the dispersion of the composite 103 and the collapse of the negative electrode active material layer 202. That is, the graphene 204 has a function of maintaining the bonding between the composites 103 even when the volume of the composites 103 increases or decreases with charge / discharge.

In addition, when applied to a flexible display device, electronic device, or the like, in a case where a power storage device such as a secondary battery is provided in a flexible portion (all or a part of the housing) and the power storage device is bent together with the portion. In addition, by repeatedly deforming the power storage device such as bending, peeling between the negative electrode current collector 201 and the composite 103 inside the power storage device may occur, and deterioration of the power storage device may be promoted.

Here, the graphene forms a three-dimensional electrical conduction network with a plurality of graphenes by bringing the graphenes into surface contact with each other. In addition, graphene is flexible and high in strength, and has an advantage that the network is not easily broken even by deformation such as bending. Therefore, a good conductive path can be maintained even after repeated deformation. In particular, when graphene is in a bag shape and encapsulates the composite 103, the composite 103 is less likely to be detached due to bending, and the electrode layer is unlikely to collapse.

The above negative electrode can be used for the power storage device which is one embodiment of the present invention.

[Method of Manufacturing Negative Electrode Structure 2]
The negative electrode active material layer 202 in the negative electrode 200 according to one embodiment of the present invention includes the graphene 204 as described above. Graphene can be obtained, for example, by kneading graphene oxide, which is a raw material of graphene, the composite 103, and a binder, and then thermally reducing it. Below, an example of the manufacturing method of such a negative electrode is demonstrated.

First, graphene oxide, which is a raw material for graphene, is prepared. Graphene oxide can be produced using various synthesis methods such as the Hummers method, the modified Hummers method, or oxidation of graphite.

For example, the Hummers method is a method of forming graphite oxide by oxidizing graphite such as scaly graphite. The formed graphite oxide is a combination of functional groups such as carbonyl group, carboxyl group, hydroxyl group, etc. due to the oxidation of graphite in some places, and the crystallinity of graphite is impaired and the distance between layers is increased. . Therefore, graphene oxide can be obtained by easily separating the layers by ultrasonic treatment or the like. Note that the length of one side (also referred to as flake size) of the graphene oxide to be manufactured is preferably several μm or more and several tens of μm or less.

Next, the graphene oxide obtained by the above method, the particulate composite 103, and the binder are added to a solvent and mixed. These mixing ratios may be appropriately adjusted according to desired battery characteristics. For example, the ratio of the particulate negative electrode active material, graphene oxide, and the binder is 80: 5: 15 by weight percent. It can be weighed to achieve a ratio.

As the solvent, a liquid in which the raw material is not dissolved and the raw material is dispersed in the solvent can be used. Further, the solvent is preferably a polar solvent, for example, water, methanol, ethanol, acetone, tetrahydrofuran (THF), dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). Any one kind or two or more kinds of mixed liquids can be used.

Also, a binder having high heat resistance, such as polyimide, is used as the binder. However, the substance mixed in the mixing step is a polyimide precursor, and the precursor is imidized in the subsequent heating step to become polyimide.

Note that, in a polar solution, graphene oxide is negatively charged due to the functional group of graphene oxide, so that different graphene oxides hardly aggregate. For this reason, in the liquid which has polarity, a graphene oxide is easy to disperse | distribute uniformly. Graphene oxide can be more uniformly dispersed in the solvent by mixing in addition to the solvent, particularly at the beginning of the mixing step. As a result, the graphene is uniformly dispersed in the negative electrode active material, and a negative electrode active material having high electrical conductivity can be manufactured.

As a method of mixing the above-mentioned compounds, for example, a kneader may be used. Examples of the kneader include a planetary kneader. The binder, the active material, and the solvent are combined and stirred using a kneader to prepare a slurry (mixture).

Here, the order of adding the graphene oxide, the particulate composite 103 and the binder to the solvent is not particularly limited. For example, after adding and mixing the particulate composite 103 in a solvent, graphene oxide can be added and mixed, and further a binder can be added and mixed. In each mixing step, a solvent may be appropriately added to adjust the viscosity of the mixture.

An example of the mixing method will be described. First, a solvent is added to the composite 103 and mixed with a kneader. As the solvent, for example, NMP may be used. Next, graphene oxide is added and kneaded. Solid kneading is kneading with high viscosity. By kneading, the aggregation of graphene oxide can be released, and the composite 103 and graphene oxide can be more uniformly dispersed. Further, a solvent may be added during the kneading. The sum of the amount of solvent added until the kneading step is preferably 0.46 ml or more and 0.80 ml or less per 1 g of active material weight, for example. Next, a binder is added and mixed with a kneader. For example, polyimide may be used as the binder. Further, a solvent is added and mixed with a kneader.

Through the above steps, a slurry (mixture) in which the particulate composite 103, the graphene oxide, the binder, and the solvent are mixed is formed.

Next, a slurry is applied on the negative electrode current collector 201, and the negative electrode current collector coated with the slurry is dried to remove the solvent. The drying step may be performed, for example, by holding in a dry atmosphere for about 1 hour at room temperature or 50 ° C. Note that when the solvent can be removed by a subsequent heating step, the drying step is not necessarily performed.

Next, the negative electrode current collector coated with the slurry is heated. The heating temperature is 200 ° C. or more and 500 ° C. or less, preferably 300 ° C. or more and 400 ° C. or less, and this is performed for 3 hours or more and 7 hours or less, preferably about 5 hours. The slurry is baked by the heating, and the polyimide precursor is imidized to become polyimide. At the same time, graphene oxide can be reduced to form graphene. Thus, since the heating for slurry baking and the heating for graphene oxide reduction can be performed together by one heating, it is not necessary to perform the heating step twice. For this reason, it is possible to reduce the manufacturing process of a negative electrode.

In the present embodiment, the heating process for slurry baking and graphene oxide reduction is performed at a temperature at which the binder is not decomposed, for example, a temperature of 300 ° C. or higher and 400 ° C. or lower. Thereby, decomposition | disassembly of a binder can be prevented and the fall of the reliability of an electrical storage apparatus can be prevented. Note that the weight of graphene oxide is almost halved by the reduction treatment.

In addition, the reduced graphene oxide has low dispersibility due to the elimination of the functional group. When graphene oxide reduced in the stage before mixing with the composite 103 or the binder (that is, graphene) is used, There is a risk that a power storage device having low electrical characteristics may be obtained as a result of being not uniformly mixed with the body 103 or the like. This is because graphene oxide is negatively charged due to bonding of oxygen-containing functional groups to the surface of graphene oxide and dispersed by repelling graphene oxide and polar solvents. Since the graphene thus obtained has lost many of these functional groups due to the reduction, the dispersibility is lowered.

Therefore, in the negative electrode active material layer formed by mixing the graphene oxide and the composite 103 and then heating the mixture, the graphene oxide is dispersed before the functional groups are reduced by the reduction. Graphene is uniformly dispersed in the negative electrode active material layer. Therefore, by performing the reduction treatment after dispersing graphene oxide, a power storage device with high electrical conductivity can be obtained.

The negative electrode 200 having the negative electrode active material layer 202 on the negative electrode current collector 201 can be manufactured by the manufacturing process as described above.

Note that various power storage devices can be formed using the above negative electrode. Examples of the power storage device include a battery, a secondary battery, a lithium ion secondary battery, and the like. Furthermore, it can also be applied to a capacitor as another example of the power storage device. For example, a capacitor such as a lithium ion capacitor can be configured by using the electrode member of one embodiment of the present invention as the negative electrode and combining this with the positive electrode of the electric double layer.

This embodiment can be implemented in combination with any of the other embodiments as appropriate.

(Embodiment 2)
In this embodiment, a structure of a power storage device using the negative electrode manufactured by the manufacturing method described in Embodiment 1 will be described with reference to FIGS. In addition, structural examples of the power storage device (storage battery) will be described with reference to FIGS. An example of an electric device will be described with reference to FIGS.

[Coin storage battery]
FIG. 5A is an external view of a coin-type (single-layer flat type) storage battery, and FIG. 5B is a cross-sectional view thereof.

In the coin-type storage battery 300, a positive electrode can 301 also serving as a positive electrode terminal and a negative electrode can 302 also serving as a negative electrode terminal are insulated and sealed with a gasket 303 formed of polypropylene or the like. Here, the negative electrode for a power storage device described in Embodiment 1 is used for the negative electrode 307.

The positive electrode 304 is formed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided so as to be in contact therewith. In addition to the positive electrode active material, the positive electrode active material layer 306 may include a binder (binder) for increasing the adhesion of the positive electrode active material, a conductive auxiliary agent for increasing the conductivity of the positive electrode active material layer, and the like. Good. As the conductive aid, a material having a large specific surface area is desirable as the conductive aid, and acetylene black (AB) or the like can be used. A carbon material such as carbon nanotube, graphene, or fullerene can also be used.

The negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode active material layer 309 provided so as to be in contact therewith. As the negative electrode 307, the negative electrode for a power storage device described in Embodiment 1 is used.

Between the positive electrode active material layer 306 and the negative electrode active material layer 309, a separator 310 and an electrolyte (not shown) are provided.

The separator 310 can be made of cellulose (paper) or an insulator such as polypropylene or polyethylene provided with pores.

The electrolyte solution uses a material having carrier ion ions as an electrolyte. Representative examples of the electrolyte include LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiCF 3 SO 3 , Li (FSO 2 ) 2 , Li (CF 3 SO 2 ) 2 N, and Li (C 2 F 5 SO 2 ). there are lithium salts such as 2 N. These electrolytes may be used individually by 1 type, and may use 2 or more types by arbitrary combinations and a ratio.

In addition, when carrier ions are alkali metal ions other than lithium ions or alkaline earth metal ions, as the electrolyte, in the lithium salt, instead of lithium, an alkali metal (for example, sodium or potassium), an alkaline earth A metal (for example, calcium, strontium, barium, beryllium, magnesium, etc.) may be used.

In addition, as the solvent of the electrolytic solution, a material that can move carrier ions is used. As a solvent for the electrolytic solution, an aprotic organic solvent is preferable. Representative examples of aprotic organic solvents include ethylene carbonate (EC), propylene carbonate, dimethyl carbonate, diethyl carbonate (DEC), γ-butyrolactone, acetonitrile, dimethoxyethane, tetrahydrofuran, etc. Can be used. Moreover, the safety | security with respect to a liquid leakage property etc. increases by using the polymeric material gelatinized as a solvent of electrolyte solution. Further, the storage battery can be made thinner and lighter. Typical examples of the polymer material to be gelated include silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide gel, polypropylene oxide gel, and fluorine polymer gel.

In addition, by using one or more ionic liquids (room temperature molten salts) that are flame retardant and volatile as an electrolyte solvent, even if the internal temperature rises due to internal short circuit or overcharge of the storage battery, etc. This can prevent the battery from bursting or igniting. An ionic liquid consists of a cation and an anion, and contains an organic cation and an anion. Examples of organic cations used in the electrolyte include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, and aromatic cations such as imidazolium cations and pyridinium cations. Moreover, as an anion used for electrolyte solution, a monovalent amide type anion, a monovalent metide type anion, a fluorosulfonate anion, a perfluoroalkylsulfonate anion, a tetrafluoroborate anion, a perfluoroalkylborate anion, a hexafluorophosphate anion Or perfluoroalkyl phosphate anions.

In particular, when an aliphatic quaternary ammonium cation is used, since the reduction resistance is high, the effect of suppressing the decomposition of the electrolytic solution accompanying charging / discharging of the power storage device is particularly high. Therefore, the capacity | capacitance fall accompanying charging / discharging can be suppressed and favorable cycling characteristics can be acquired. In addition, the capacity of the power storage device can be increased.

Further, instead of the electrolytic solution, a solid electrolyte having an inorganic material such as sulfide or oxide, or a solid electrolyte having a polymer material such as PEO (polyethylene oxide) can be used. When a solid electrolyte is used, it is not necessary to install a separator or a spacer. Further, since the entire battery can be solidified, there is no risk of leakage and the safety is greatly improved.

For the positive electrode can 301 and the negative electrode can 302, a metal such as nickel, aluminum, titanium, or the like having corrosion resistance to the electrolyte, or an alloy thereof or an alloy of these with another metal (for example, stainless steel) is used. be able to. Moreover, in order to prevent the corrosion by electrolyte solution, it is preferable to coat | cover with nickel, aluminum, etc. The positive electrode can 301 and the negative electrode can 302 are electrically connected to the positive electrode 304 and the negative electrode 307, respectively.

The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated in the electrolyte, and the positive electrode 304, the separator 310, the negative electrode 307, and the negative electrode can 302 are laminated in this order with the positive electrode can 301 facing down, as shown in FIG. Then, the positive electrode can 301 and the negative electrode can 302 are pressure-bonded via a gasket 303 to manufacture a coin-shaped storage battery 300.

Here, the flow of current when the power storage device is charged will be described with reference to FIG. When a secondary battery using lithium ions is regarded as one closed circuit, the movement of lithium ions and the current flow are in the same direction. In a secondary battery using lithium ions, the anode (anode) and the cathode (cathode) are interchanged by charging and discharging, and the oxidation reaction and the reduction reaction are interchanged. Therefore, the electrode having a high reaction potential is called the positive electrode. An electrode having a low reaction potential is called a negative electrode. Therefore, in the present specification, the positive electrode is referred to as “positive electrode” or “whether the battery is being charged, discharged, a reverse pulse current is applied, or a charge current is applied. The positive electrode is referred to as a “positive electrode”, and the negative electrode is referred to as a “negative electrode” or a “− electrode (negative electrode)”. If the terms anode (anode) and cathode (cathode) related to the oxidation reaction or reduction reaction are used, the charge and discharge are reversed, which may cause confusion. Therefore, the terms anode (anode) and cathode (cathode) are not used in this specification. If the terms anode (anode) or cathode (cathode) are used, specify whether charging or discharging, and indicate whether it corresponds to the positive electrode (positive electrode) or the negative electrode (negative electrode). To do.

A charger is connected to the two terminals shown in FIG. 5C, and the storage battery 400 is charged. As charging of the storage battery 400 proceeds, the potential difference between the electrodes increases. In FIG. 5C, the battery flows from the external terminal of the storage battery 400 toward the positive electrode 402, flows in the storage battery 400 from the positive electrode 402 toward the negative electrode 404, and flows from the negative electrode toward the external terminal of the storage battery 400. The direction of current is positive. That is, the direction in which the charging current flows is the current direction.

[Cylindrical storage battery]
Next, an example of a cylindrical storage battery will be described with reference to FIG. As shown in FIG. 6A, the cylindrical storage battery 600 has a positive electrode cap (battery lid) 601 on the top surface and a battery can (outer can) 602 on the side surface and bottom surface. The positive electrode cap and the battery can (outer can) 602 are insulated by a gasket (insulating packing) 610.

FIG. 6B is a diagram schematically showing a cross section of a cylindrical storage battery. Inside the hollow cylindrical battery can 602, a battery element in which a strip-like positive electrode 604 and a negative electrode 606 are wound with a separator 605 interposed therebetween is provided. Although not shown, the battery element is wound around a center pin. The battery can 602 has one end closed and the other end open. For the battery can 602, a metal such as nickel, aluminum, titanium, or the like having corrosion resistance to the electrolytic solution, or an alloy thereof or an alloy of these with another metal (for example, stainless steel) can be used. . In order to prevent corrosion due to the electrolytic solution, it is preferable to coat nickel, aluminum, or the like. Inside the battery can 602, the battery element in which the positive electrode, the negative electrode, and the separator are wound is sandwiched between a pair of opposing insulating plates 608 and 609. Further, a non-aqueous electrolyte (not shown) is injected into the inside of the battery can 602 provided with the battery element. The non-aqueous electrolyte can be the same as the coin-type storage battery.

As the negative electrode 606, the negative electrode for a power storage device described in Embodiment 1 is used. The positive electrode 604 and the negative electrode 606 may be manufactured in the same manner as the positive electrode and the negative electrode of the coin-type storage battery described above. However, since the positive electrode and the negative electrode used in the cylindrical storage battery are wound, an active material is formed on both surfaces of the current collector. It differs in the point to do. A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collecting lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can use a metal material such as aluminum. The positive terminal 603 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC element (Positive Temperature Coefficient) 611. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the increase in the internal pressure of the battery exceeds a predetermined threshold value. The PTC element 611 is a heat-sensitive resistance element that increases in resistance when the temperature rises, and prevents abnormal heat generation by limiting the amount of current by increasing the resistance. For the PTC element, barium titanate (BaTiO 3 ) -based semiconductor ceramics or the like can be used.

[Thin storage battery]
Next, an example of a thin storage battery will be described with reference to FIG. If the thin storage battery is configured to have flexibility, if the thin storage battery is mounted on an electronic device having at least a part of the flexibility, the storage battery can be bent in accordance with the deformation of the electronic device.

FIG. 7 shows an external view of a thin storage battery 500. 8A and 8B show an A1-A2 cross section and a B1-B2 cross section indicated by a dashed line in FIG. A thin storage battery 500 includes a positive electrode 503 having a positive electrode current collector 501 and a positive electrode active material layer 502, a negative electrode 506 having a negative electrode current collector 504 and a negative electrode active material layer 505, a separator 507, an electrolyte solution 508, and an exterior. And a body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in the exterior body 509. The exterior body 509 is filled with the electrolytic solution 508. As the negative electrode 506, the negative electrode for a power storage device described in Embodiment 1 is used.

The separator 507 is preferably processed into a bag shape and disposed so as to wrap either the positive electrode 503 or the negative electrode 506. For example, as illustrated in FIG. 9A, the separator 507 is folded in half so as to sandwich the positive electrode 503, and is sealed by a sealing portion 514 outside a region overlapping with the positive electrode 503, whereby the positive electrode 503 is separated from the separator 507. It can be reliably carried inside. Then, as shown in FIG. 9B, a thin storage battery 500 may be formed by alternately stacking positive electrodes 503 and negative electrodes 506 wrapped in a separator 507 and arranging them in an exterior body 509.

FIG. 10B shows an example in which a current collector is welded to the lead electrode. As an example, an example in which the positive electrode current collector 501 is welded to the positive electrode lead electrode 510 is shown. The positive electrode current collector 501 is welded to the positive electrode lead electrode 510 in the welding region 512 using ultrasonic welding or the like. Further, since the positive electrode current collector 501 includes the curved portion 513 illustrated in FIG. 10B, stress generated by external force applied after the storage battery 500 is manufactured can be relieved, and the reliability of the storage battery 500 can be reduced. Can be increased.

7 and 8, in the thin storage battery 500, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are ultrasonically bonded to the positive electrode current collector 501 and the negative electrode current collector 504, respectively. In addition, the positive electrode current collector 501 and the negative electrode current collector 504 can also serve as terminals for obtaining electrical contact with the outside. In that case, a part of the positive electrode current collector 501 and the negative electrode current collector 504 may be disposed so as to be exposed to the outside from the exterior body 509 without using the lead electrode.

In the thin storage battery 500, the exterior body 509 is provided with a metal thin film having excellent flexibility such as aluminum, stainless steel, copper, and nickel on a film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, and polyamide. Furthermore, a film having a three-layer structure in which an insulating synthetic resin film such as a polyamide resin or a polyester resin is provided on the metal thin film as the outer surface of the outer package can be used.

In FIG. 7, the number of electrode layers is 3 as an example, but of course, the number of electrode layers is not limited to 3, and may be more or less. When there are many electrode layers, it can be set as the storage battery which has more capacity | capacitance. Moreover, when there are few electrode layers, it can be made thin and can be set as the storage battery excellent in flexibility.

In the present embodiment, coin-shaped, cylindrical and thin storage batteries are shown as the storage battery, but various types of storage batteries such as other sealed storage batteries and rectangular storage batteries can be used. Alternatively, a structure in which a plurality of positive electrodes, negative electrodes, and separators are stacked, or a structure in which positive electrodes, negative electrodes, and separators are wound may be employed.

The negative electrode active material layer according to one embodiment of the present invention is used for the negative electrodes of the storage battery 300, the storage battery 500, and the storage battery 600 described in this embodiment. Therefore, the discharge capacity of the storage battery 300, the storage battery 500, and the storage battery 600 can be increased. Alternatively, cycle characteristics can be improved.

The thin storage battery is not limited to FIG. An example of another thin storage battery is shown in FIG. A wound body 993 illustrated in FIG. 11A includes a negative electrode 994, a positive electrode 995, and a separator 996.

The wound body 993 is obtained by winding the laminated sheet by laminating the negative electrode 994 and the positive electrode 995 with the separator 996 interposed therebetween. A rectangular secondary battery is manufactured by covering the wound body 993 with a rectangular sealing container or the like.

In addition, what is necessary is just to design the number of lamination | stacking which consists of the negative electrode 994, the positive electrode 995, and the separator 996 suitably according to a required capacity | capacitance and element volume. The negative electrode 994 is connected to a negative electrode current collector (not shown) via one of a lead electrode 997 and a lead electrode 998, and the positive electrode 995 is connected to the positive electrode current collector (not shown) via the other of the lead electrode 997 and the lead electrode 998. Connected).

A power storage device 990 illustrated in FIGS. 11B and 11C includes the above-described wound body 993 in a space formed by bonding a film 981 and a film 982 having a concave portion by thermocompression bonding or the like. is there. The wound body 993 includes a lead electrode 997 and a lead electrode 998, and is impregnated with an electrolytic solution inside the film 981 and the film 982 having a recess.

For the film 981 and the film 982 having a recess, for example, a metal material such as aluminum or a resin material can be used. If a resin material is used as the material of the film 981 and the film 982 having a recess, the film 981 and the film 982 having a recess can be deformed when an external force is applied, and a flexible storage battery is manufactured. be able to.

11B and 11C show an example in which two films are used, a space is formed by bending one film, and the winding body 993 described above is accommodated in the space. May be.

In addition, a flexible power storage device can be manufactured by using a resin material or the like for the exterior body of the power storage device or the sealing container. However, when the exterior body or the sealing container is made of a resin material, the portion to be connected to the outside is made of a conductive material.

For example, an example of a prismatic storage battery having flexibility is shown in FIG. Since the wound body 993 in FIG. 12A is the same as that shown in FIG. 11A, detailed description thereof will be omitted.

A power storage device 990 illustrated in FIGS. 12B and 12C is obtained by housing the winding body 993 described above inside an exterior body 991. The wound body 993 has a lead electrode 997 and a lead electrode 998, and is impregnated with an electrolytic solution inside the exterior bodies 991, 992. For the exterior bodies 991, 992, for example, a metal material such as aluminum or a resin material can be used. When a resin material is used as the material of the exterior bodies 991 and 992, the exterior bodies 991 and 992 can be deformed when a force is applied from the outside, and a flexible prismatic storage battery can be manufactured.

Further, structural examples of the power storage device (power storage unit) will be described with reference to FIGS. 13, 14, and 15.

FIGS. 13A and 13B are external views of a power storage device. The power storage device includes a circuit board 900 and a power storage unit 913. A label 910 is attached to the power storage unit 913. Further, as illustrated in FIG. 13B, the power storage device includes a terminal 951, a terminal 952, an antenna 914, and an antenna 915.

The circuit board 900 has a terminal 911 and a circuit 912. The terminal 911 is connected to the terminal 951, the terminal 952, the antenna 914, the antenna 915, and the circuit 912. Note that a plurality of terminals 911 may be provided, and each of the plurality of terminals 911 may be a control signal input terminal, a power supply terminal, or the like.

The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 914 and the antenna 915 are not limited to a coil shape, and may be a linear shape or a plate shape, for example. An antenna such as a planar antenna, an aperture antenna, a traveling wave antenna, an EH antenna, a magnetic field antenna, or a dielectric antenna may be used. Alternatively, the antenna 914 or the antenna 915 may be a flat conductor. The flat conductor can function as one of electric field coupling conductors. That is, the antenna 914 or the antenna 915 may function as one of the two conductors of the capacitor. Thereby, not only an electromagnetic field and a magnetic field but power can also be exchanged by an electric field.

The line width of the antenna 914 is preferably larger than the line width of the antenna 915. Accordingly, the amount of power received by the antenna 914 can be increased.

The power storage device includes a layer 916 between the antenna 914 and the antenna 915 and the power storage unit 913. The layer 916 has a function of shielding an electromagnetic field generated by the power storage unit 913, for example. As the layer 916, for example, a magnetic material can be used.

Note that the structure of the power storage device is not limited to that shown in FIG.

For example, as illustrated in FIGS. 14A-1 and 14A-2, antennas are provided on each of a pair of opposing surfaces of the power storage unit 913 illustrated in FIGS. 13A and 13B. May be provided. 14A-1 is an external view seen from one side direction of the pair of surfaces, and FIG. 14A-2 is an external view seen from the other side direction of the pair of surfaces. Note that for the same portion as the power storage device illustrated in FIGS. 13A and 13B, the description of the power storage device illustrated in FIGS. 13A and 13B can be incorporated as appropriate.

As shown in FIG. 14A-1, an antenna 914 is provided on one of a pair of surfaces of the power storage unit 913 with the layer 916 interposed therebetween, and as shown in FIG. 14A-2, a pair of power storage units 913 is provided. An antenna 915 is provided on the other side of the surface with the layer 917 interposed therebetween. The layer 917 has a function of shielding an electromagnetic field generated by the power storage unit 913, for example. As the layer 917, for example, a magnetic material can be used.

By using the above structure, the size of both the antenna 914 and the antenna 915 can be increased.

Alternatively, as illustrated in FIGS. 14B-1 and 14B-2, each of the pair of opposing surfaces of the power storage unit 913 illustrated in FIGS. 13A and 13B is separated. An antenna may be provided. 14B-1 is an external view seen from one side direction of the pair of surfaces, and FIG. 14B-2 is an external view seen from the other side direction of the pair of surfaces. Note that for the same portion as the power storage device illustrated in FIGS. 13A and 13B, the description of the power storage device illustrated in FIGS. 13A and 13B can be incorporated as appropriate.

As illustrated in FIG. 14B-1, an antenna 914 and an antenna 915 are provided on one of a pair of surfaces of the power storage unit 913 with the layer 916 interposed therebetween, and as illustrated in FIG. 14B-2, the power storage unit An antenna 918 is provided on the other of the pair of surfaces of 913 with the layer 917 interposed therebetween. The antenna 918 has a function of performing data communication with an external device, for example. For the antenna 918, for example, an antenna having a shape applicable to the antenna 914 and the antenna 915 can be used. As a communication method between the power storage device and other devices via the antenna 918, a response method that can be used between the power storage device and other devices, such as NFC, can be used.

Alternatively, as illustrated in FIG. 15A, a display device 920 may be provided in the power storage unit 913 illustrated in FIGS. 13A and 13B. The display device 920 is electrically connected to the terminal 911 through the terminal 919. Note that the label 910 is not necessarily provided in a portion where the display device 920 is provided. Note that for the same portion as the power storage device illustrated in FIGS. 13A and 13B, the description of the power storage device illustrated in FIGS. 13A and 13B can be incorporated as appropriate.

The display device 920 may display, for example, an image indicating whether charging is being performed, an image indicating the amount of stored power, or the like. As the display device 920, for example, electronic paper, a liquid crystal display device, an electroluminescence (also referred to as EL) display device, or the like can be used. For example, power consumption of the display device 920 can be reduced by using electronic paper.

Alternatively, as illustrated in FIG. 15B, a sensor 921 may be provided in the power storage unit 913 illustrated in FIGS. 13A and 13B. The sensor 921 is electrically connected to the terminal 911 through the terminal 922. Note that for the same portion as the power storage device illustrated in FIGS. 13A and 13B, the description of the power storage device illustrated in FIGS. 13A and 13B can be incorporated as appropriate.

Examples of the sensor 921 include force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, and radiation. Those having a function of measuring flow rate, humidity, gradient, vibration, odor or infrared ray can be used. By providing the sensor 921, for example, data (such as temperature) indicating an environment where the power storage device is placed can be detected and stored in a memory in the circuit 912.

FIG. 16 shows an example in which the flexible storage battery shown in FIGS. 7, 11, and 12 is mounted on an electronic device. As an electronic device to which a power storage device having a flexible shape is applied, for example, a television device (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (Also referred to as a mobile phone or a mobile phone device), a portable game machine, a portable information terminal, a sound reproduction device, a large game machine such as a pachinko machine, and the like.

Also, a power storage device having a flexible shape can be incorporated along the inner or outer wall of a house or building, or along the curved surface of the interior or exterior of an automobile.

FIG. 16A illustrates an example of a mobile phone. A mobile phone 7400 is provided with a display portion 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone 7400 includes a power storage device 7407.

FIG. 16B shows a state where the mobile phone 7400 is bent. When the cellular phone 7400 is deformed by an external force to bend the whole, the power storage device 7407 provided therein is also curved. At that time, the bent state of the power storage device 7407 is illustrated in FIG. The power storage device 7407 is a thin storage battery. The power storage device 7407 is fixed in a bent state. Note that the power storage device 7407 includes a lead electrode 7408 electrically connected to the current collector 7409. For example, the current collector 7409 is a copper foil, which is partly alloyed with gallium to improve adhesion with the active material layer in contact with the current collector 7409, and reliability in a state where the power storage device 7407 is bent. Has a high configuration.

FIG. 16D illustrates an example of a bangle display device. A portable display device 7100 includes a housing 7101, a display portion 7102, operation buttons 7103, and a power storage device 7104. FIG. 16E illustrates a state of the power storage device 7104 bent. When the power storage device 7104 is bent and attached to the user's arm, the housing is deformed and the curvature of part or all of the power storage device 7104 changes. Note that the curvature at a given point of the curve expressed by the value of the radius of the corresponding circle is the curvature radius, and the reciprocal of the curvature radius is called the curvature. Specifically, part or all of the main surface of the housing or the power storage device 7104 changes within a range where the radius of curvature R is 40 mm or greater and 150 mm or less. When the radius of curvature R on the main surface of the power storage device 7104 is in the range of 40 mm to 150 mm, high reliability can be maintained. Note that the power storage device 7104 includes a lead electrode 7105 electrically connected to the current collector 7106. For example, the current collector 7106 is a copper foil, and is partly alloyed with gallium to improve adhesion with the active material layer in contact with the current collector 7106, and the number of times that the power storage device 7104 is bent while changing its curvature. However, at most, high reliability can be maintained.

FIG. 16F illustrates an example of a wristwatch-type portable information terminal. A portable information terminal 7200 includes a housing 7201, a display portion 7202, a band 7203, a buckle 7204, operation buttons 7205, an input / output terminal 7206, and the like.

The portable information terminal 7200 can execute various applications such as mobile phone, electronic mail, text browsing and creation, music playback, Internet communication, and computer games.

The display portion 7202 is provided with a curved display surface, and can display along the curved display surface. The display portion 7202 includes a touch sensor and can be operated by touching the screen with a finger, a stylus, or the like. For example, an application can be started by touching an icon 7207 displayed on the display portion 7202.

The operation button 7205 can have various functions such as power on / off operation, wireless communication on / off operation, manner mode execution and release, and power saving mode execution and release, in addition to time setting. . For example, the function of the operation button 7205 can be freely set by an operating system incorporated in the portable information terminal 7200.

Further, the portable information terminal 7200 can perform short-range wireless communication with a communication standard. For example, it is possible to talk hands-free by communicating with a headset capable of wireless communication.

Further, the portable information terminal 7200 is provided with an input / output terminal 7206, and can directly exchange data with other information terminals via a connector. Charging can also be performed through the input / output terminal 7206. Note that the charging operation may be performed by wireless power feeding without using the input / output terminal 7206.

The display portion 7202 of the portable information terminal 7200 includes a power storage device including the electrode member of one embodiment of the present invention. For example, the power storage device 7104 illustrated in FIG. 16E can be incorporated in the housing 7201 in a curved state or in the band 7203 in a bendable state.

[Example of electrical equipment: Example of mounting on a vehicle]
Next, an example in which a storage battery is mounted on a vehicle will be described. When the storage battery is mounted on a vehicle, a next-generation clean energy vehicle such as a hybrid vehicle (HEV), an electric vehicle (EV), or a plug-in hybrid vehicle (PHEV) can be realized.

FIG. 17 illustrates a vehicle using one embodiment of the present invention. A car 8100 illustrated in FIG. 17A is an electric car using an electric motor as a power source for traveling. Or it is a hybrid vehicle which can select and use an electric motor and an engine suitably as a motive power source for driving | running | working. By using one embodiment of the present invention, a vehicle having a long cruising distance can be realized. The automobile 8100 includes a power storage device. The power storage device not only drives the electric motor 8106 but can supply power to a light-emitting device such as a headlight 8101 or a room light (not shown).

Further, the power storage device can supply power to a display device such as a speedometer or a tachometer that the automobile 8100 has. The power storage device can supply power to a semiconductor device such as a navigation gate system included in the automobile 8100.

An automobile 8100 illustrated in FIG. 17B can be charged by receiving power from an external charging facility by a plug-in method, a non-contact power supply method, or the like in a power storage device included in the automobile 8100. FIG. 17B illustrates a state in which the power storage device mounted on the automobile 8100 is charged from the ground-installed charging device 8021 through the cable 8022. When charging, the charging method, connector standard, and the like may be appropriately performed by a predetermined method such as CHAdeMO (registered trademark) or a combo. The charging device 8021 may be a charging station provided in a commercial facility, or may be a household power source. For example, the power storage device mounted on the automobile 8100 can be charged by power supply from the outside by plug-in technology. Charging can be performed by converting AC power into DC power via a converter such as an ACDC converter.

Although not shown, the power receiving device can be mounted on the vehicle and charged by supplying power from the ground power transmitting device in a non-contact manner. In the case of this non-contact power supply method, charging can be performed not only when the vehicle is stopped but also during traveling by incorporating a power transmission device on a road or an outer wall. In addition, this non-contact power feeding method may be used to transmit and receive power between vehicles. Furthermore, a solar battery may be provided in the exterior portion of the vehicle, and the power storage device may be charged when the vehicle is stopped or traveling. An electromagnetic induction method or a magnetic field resonance method can be used for such non-contact power supply.

According to one embodiment of the present invention, the cycle characteristics of the power storage device are improved, and the reliability can be improved. According to one embodiment of the present invention, characteristics of the power storage device can be improved, and thus the power storage device itself can be reduced in size and weight. If the power storage device itself can be reduced in size and weight, the cruising distance can be improved because it contributes to weight reduction of the vehicle. In addition, a power storage device mounted on a vehicle can be used as a power supply source other than the vehicle. In this case, it is possible to avoid using a commercial power source at the peak of power demand.

This embodiment can be implemented in combination with any of the other embodiments as appropriate.

In the following examples, a half cell was manufactured using the negative electrode shown in Embodiment 1, and cycle characteristics were evaluated.

(Production of composite and comparative sample)
A composite and a comparative sample were prepared. There are seven samples, Sample A, Sample B, Sample C, Sample D, Sample E, Comparative Sample F, and Comparative Sample G. Samples containing composite fine particles are Sample A to Sample E.

First, a method for producing Sample A will be described. Weigh 14.8 g of titanium powder having a particle size of 45 μm and 5.2 g of silicon powder having a particle size of 5 μm. Weighed titanium powder, silicon powder, and media are put into a crushing container (made of chromium steel, capacity 500 ml) attached to a planetary rotation type ball mill type crusher (LP-4, manufactured by Ito Seisakusho). The medium is a chromium steel ball having a diameter of 10 mm, and the amount is a volume (50 pieces, approximately 200 g) occupying 1/3 of the grinding container. The composite of sample A1 was produced by making the inside of a grinding | pulverization container into Ar atmosphere, and carrying out the rotation revolution stirring for 140 hours at 250 rpm. Subsequently, 10.0 g of sample A1 and 10.0 g of silicon powder having a particle size of 5 μm were weighed, and a composite of sample A was prepared by performing rotation and revolution stirring for 65 hours under the same conditions as described above.

Samples B to E and comparative sample G were also prepared by setting the same atmosphere and rotation speed using the above-described pulverizer. The raw materials weighed in the preparation of each sample and the processing time by the pulverizer are listed below. Sample B was prepared by performing treatment for 250 hours using 4.6 g of titanium powder having a particle size of 45 μm and 15.4 g of silicon powder having a particle size of 5 μm. Sample C was prepared by performing a treatment for 250 hours using 10.0 g of titanium silicide (TiSi 2 ) powder and 10.0 g of silicon powder having a particle size of 5 μm. Sample D was prepared by performing treatment for 250 hours using 7.66 g of tungsten powder having a particle size of 53 μm and 12.34 g of silicon powder having a particle size of 5 μm. Sample E was treated for 250 hours using 7.63 g of tantalum powder having a particle size of 45 μm and 12.37 g of silicon powder having a particle size of 5 μm. Comparative sample G was treated for 60 hours using 20.0 g of silicon powder having a particle size of 5 μm.

Comparative sample F is a silicon powder having a particle size of 5 μm.

<SEM observation results>
FIG. 18 shows SEM (Scanning Electron Microscope) observation results and SEM-EDX (Energy Dispersive X-ray Spectroscopy) analysis results of Sample A. 18A is an SEM image of sample A, FIG. 18B is a mapping image of Si, and FIG. 18C is a mapping image of Ti. 18B and 18C, it can be seen that Si and Ti are almost uniformly distributed in the composite 103.

<Results of XRD analysis>
FIG. 19 shows XRD spectra of Sample A, crystalline Si, and various crystalline TiSi 2 . The spectra other than sample H are literature values. In sample A, peaks derived from TiSi 2 space group Cmcm were observed in the vicinity of 2θ of 41 deg, 51 deg, and 66 deg. Thus, it was confirmed that sample A had TiSi 2 . On the other hand, since the peak in the vicinity of 28 deg derived from crystalline Si is broad, it was confirmed that Si present in sample A has low crystallinity. In addition, since the XRD spectrum of sample A has a plurality of peaks overlapping in the range of 38 deg to 43 deg, sample A has TiSi 2 space group FddZ and TiSi 2 space group Fmmm in addition to TiSi 2 space group Cmcm. It is considered that such a space group has a plurality of different crystal phases.

FIG. 20 shows XRD (X-Ray Diffraction) spectra of Sample B, crystalline Si, various crystalline TiSi 2, and crystalline metal Ti. The spectra other than sample B are literature values. In sample B, since 2θ was observed in the vicinity of 39 deg, 43 deg, and 50 deg, a peak derived from the TiSi 2 space group FddZ was observed, so it was confirmed that sample B had TiSi 2 . On the other hand, since a peak near 28 deg derived from crystalline Si is slightly observed, the crystallinity of Si present in sample B is considered to be low crystallinity with a crystallite size of 10 nm or less. Moreover, since the peak in the vicinity of 40 deg derived from the crystalline metal Ti is almost broad, it is considered that Ti contained in the sample B has low crystallinity.

FIG. 21 shows XRD spectra of Sample C, crystalline Si, various crystalline TiSi 2, and crystalline metal Ti. The spectra other than sample C are literature values. Sample C shows the same tendency as Sample B. Accordingly, Sample C has a TiSi 2. Further, the crystallinity of silicon contained in the sample C is low crystallinity with a crystallite size of 10 nm or less, and Ti contained in the sample C is considered to have low crystallinity.

FIG. 22 shows XRD spectra of Sample D, crystalline Si, crystalline WSi 2 and various metals W. The spectra other than sample D are literature values. In sample D, since 2θ was observed in the vicinity of 23 deg, 30 deg, 40 deg, and 45 deg, a peak derived from WSi 2 space group I4 mmm, it was confirmed that sample D had WSi 2 . On the other hand, since the peak in the vicinity of 28 deg derived from crystalline Si is almost broad, Si existing in sample D is considered to have low crystallinity. In addition, since W-derived peaks in the vicinity of 38 deg and 41 deg are slightly observed, W contained in the sample D is considered to have low crystallinity.

FIG. 23 shows XRD spectra of Sample E, crystalline Si, crystalline TaSi 2 and metal Ta. The spectra other than sample E are literature values. In sample E, since 2θ was observed in the vicinity of 25 deg, 40 deg, and 47 deg, a peak derived from TaSi 2 space group P64 2 2 was observed, so it was confirmed that sample E had TaSi 2 . On the other hand, since the peak in the vicinity of 28 deg derived from crystalline Si is almost broad, Si existing in sample E is considered to have low crystallinity. Moreover, since the peak in the vicinity of 39 deg derived from Ta is almost broad, it is considered that Ta contained in the sample E has low crystallinity.

Table 1 shows the raw materials used for the preparation of each sample, the processing conditions by the pulverizer, the average particle diameter, and the value of D90. The particle size was measured using a laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation). In addition, a laser diffraction / scattering method was used as a particle size calculation method.

Figure JPOXMLDOC01-appb-T000001

(Preparation of negative electrode)
Using the obtained Sample A to Sample E, Comparative Sample F, and Comparative Sample G, an electrode was produced by the following method. That is, a 10 μm-thick stainless steel foil with nickel coated on the surface is used as an electrode current collector, composite particles or Si particles, acetylene black, and a polyimide as a binder (more precisely, a precursor of polyimide) The mixture was mixed at 80: 5: 15 (% by weight) using a planetary kneader to prepare a slurry. NMP was used as the solvent. First, NMP, which is a solvent, was added to the composite particles or Si particles and acetylene black and kneaded. Next, a polyimide precursor and NMP were added and mixed with a kneader. The kneading conditions were such that the number of rotations was 2000 rpm, 5 minutes, and kneading was performed 7 times including solid kneading. Next, the slurry was apply | coated to the electrical power collector using the blade method. The operation speed of the blade was 10 mm / sec. NMP was vaporized by drying at 50 ° C. for 1 hour in an air atmosphere. Next, in order to imidize the polyimide precursor, a heat treatment was performed at 400 ° C. for 5 hours in a nitrogen atmosphere.

In this way, a negative electrode having each sample was produced. For each sample other than sample A, two types of negative electrodes having different loadings were prepared. The negative electrode produced using Sample A is referred to as Negative Electrode A. Two types of negative electrodes prepared using Sample B are referred to as a negative electrode B1 and a negative electrode B2, respectively. Similarly, two types of negative electrodes prepared using Sample C, Sample D, Sample E, Comparative Sample F, and Comparative Sample G are respectively referred to as negative electrode C1, negative electrode C2, negative electrode D1, negative electrode D2, negative electrode E1, and negative electrode E2. Comparative negative electrode F1, comparative negative electrode F2, comparative negative electrode G1, and comparative negative electrode G2. Table 2 shows the loading amount of the sample in each negative electrode.

Figure JPOXMLDOC01-appb-T000002

(Manufacture of cells)
Next, a half cell was produced using each negative electrode produced as described above. For the evaluation of the characteristics, a coin type storage battery of CR2032 type (diameter 20 mm, height 3.2 mm) was used. Metal lithium was used for the counter electrode and polypropylene was used for the separator. As the electrolytic solution, 1 mol / l LiPF 6 was used as a solute, and EC and DEC were mixed at a volume ratio of 3: 7 as a solvent. A half cell produced by using the negative electrode A, the negative electrode B1, the negative electrode C1, the negative electrode D1, the negative electrode E1, the comparative negative electrode F1, and the comparative negative electrode G1 is cell A, cell B1, cell C1, cell D1, cell E1, cell F1, This is referred to as cell G1 and is referred to as a low loading cell. Moreover, the half cell produced using the negative electrode B2, the negative electrode C2, the negative electrode D2, the negative electrode E2, the negative electrode for comparison F2, and the negative electrode for comparison G2 is designated as cell B2, cell C2, cell D2, cell E2, cell F2, and cell G2, respectively. This is called a high load cell.

(Cell measurement)
Next, measurement results of charge / discharge characteristics and cycle characteristics of the various cells produced as described above will be described.

Describe the measurement conditions for half-cells. The charge / discharge method is constant current-constant voltage charge and constant current discharge at a rate of 0.1 C only for the first charge / discharge, and constant current-constant voltage charge and constant current discharge at a rate of 0.2 C for the second and subsequent times. Went. The upper limit voltage of charging / discharging was 1.5V, and the lower limit voltage was 0.01V. The measurement temperature was 25 ° C. The rate of the active material is calculated based on 4190 mAh / g per sample loading of the high loading cell (cell F2, cell G2) including various low loading cells and comparative samples, and the cells B2 to E2 are The calculation is based on 2000 mAh / g per sample loading. A discharge rate and a charge rate will be described. The discharge rate is the relative ratio of the current during discharge to the battery capacity, and is expressed in units C. In a battery with a rated capacity X (Ah), the current corresponding to 1 C is X (A). When discharged at a current of 2X (A), it is said that it was discharged at 2C, and when discharged at a current of X / 5 (A), it was discharged at 0.2C. The charging rate is also the same. When charging with a current of 2X (A), it is said to be charged at 2C. When charging with a current of X / 5 (A), it is charged at 0.2C. It was said.

Table 3 shows the initial discharge capacity obtained as a result of the charge / discharge of the low supported amount cells (cell A, cell B1 to cell F1), the capacity retention rate after 10 cycles with respect to the initial discharge capacity, and the initial discharge capacity. The capacity retention rate after 20 cycles is shown.

Figure JPOXMLDOC01-appb-T000003

FIG. 24 and FIG. 25 show the first (1st cycle) and second (2nd cycle) charge / discharge curves (also referred to as charge / discharge characteristics) of the low loading amount cell. Specifically, FIG. 24A shows the cell F1, FIG. 24B shows the cell G1, FIG. 24C shows the cell A, FIG. 24D shows the cell B1, and FIG. FIG. 25B is a charge / discharge curve of the cell C1, FIG. 25B is a charge / discharge curve of the cell D1, and FIG.

24 and 25, the horizontal axis represents capacity (mAh / g), and the vertical axis represents voltage (V). The first charge / discharge curve is indicated by a solid line, and the second charge / discharge curve is indicated by a broken line. 24A and 24B are different from those in FIGS. 24C and 24D and FIGS. 25A to 25C.

FIG. 26 shows the transition of the capacity retention rate when the initial discharge capacity of the low load cell is 100%. The result of cell A is a thick solid line, the result of cell B1 is a thin solid line, the result of cell C1 is a one-dot chain line, the result of cell D1 is a two-dot chain line, the result of cell E1 is a broken line, and the result of cell F1 is The thin dotted line represents the result of the cell G1 with a thick dotted line.

Subsequently, Table 4 shows the initial discharge capacity obtained as a result of charging / discharging of the high load amount cells (cell B2 to cell F2), the capacity maintenance rate after 10 cycles with respect to the initial discharge capacity, and 20 with respect to the initial discharge capacity. The capacity retention rate after cycling is shown. Note that the capacity retention ratios after 20 cycles of the cell C2 and the cell D2 are not described because they are being measured.

Figure JPOXMLDOC01-appb-T000004

FIG. 27 shows the transition of the capacity retention rate when the initial discharge capacity of the high load cell is 100%. The result of cell B2 is indicated by a thin solid line, the result of cell C2 is indicated by a one-dot chain line, the result of cell D2 is indicated by a two-dot chain line, the result of cell E2 is indicated by a broken line, the result of cell F2 is indicated by a thin dotted line, and the result of cell G2 is indicated. Represented by a thick dotted line. Note that the capacity retention rates of the cell C2 and the cell D2 after 11 cycles are not described because they are being measured.

From Table 2, Table 3, FIG. 26, and FIG. 27, the use of Sample A to Sample E having the composite as the negative electrode suppresses the deterioration of the active material and the side reaction with the electrolytic solution that accompany expansion and contraction. It was shown that the capacity maintenance rate of can be increased. That is, by using the negative electrode for a power storage device of one embodiment of the present invention, the capacity retention rate of the power storage device can be increased.

In the following examples, a half cell was produced using a negative electrode different from that in Example 1, and the cycle characteristics were evaluated.

(Production of composite and comparative sample)
Composite fine particles were prepared. First, 14.8 g of titanium powder having a particle size of 45 μm and 5.2 g of silicon powder having a particle size of 5 μm are weighed. Weighed titanium powder, silicon powder, and media are put into a grinding container (made of chromium, capacity 500 ml) attached to a planetary rotation type ball mill type grinding machine (LP-4, manufactured by Ito Seisakusho). The medium is a chromium steel ball having a diameter of 10 mm, and the amount is a volume (50 pieces, approximately 200 g) occupying 1/3 of the grinding container. The composite of sample H1 was produced by carrying out rotation revolution stirring at the rotation speed of 250 rpm by making the inside of a grinding | pulverization container into argon atmosphere. The treatment time at this time is 140 hours, but the sample was taken out from the pulverization container several times during the treatment and stirred. Subsequently, 10.0 g of sample H1 and 10.0 g of silicon powder having a particle size of 5 μm were weighed, and a composite of sample H was prepared by performing rotation and revolution stirring for 65 hours under the same conditions as described above.

Next, a method for producing a comparative sample will be described. Comparative sample I is a silicon powder having a particle size of 5 μm. Comparative sample J was prepared by weighing 20.0 g of silicon powder having a particle size of 5 μm and performing rotation and revolution stirring for 60 hours under the same conditions as described above. In the preparation of the comparative sample J, the sample was taken out of the pulverization container and stirred every time the rotation and revolution stirring was performed for 20 hours.

Table 5 shows the raw materials used for the preparation of each sample, the processing conditions by the pulverizer, the average particle diameter, and the value of D90. The particle size was measured using a laser diffraction particle size distribution analyzer (SALD-2200, manufactured by Shimadzu Corporation). In addition, a laser diffraction / scattering method was used as a particle size calculation method. In the case of the laser diffraction / scattering method, an effective diameter is calculated by fitting an ideal diffraction pattern obtained assuming a spherical shape and an actually measured diffraction pattern.

Figure JPOXMLDOC01-appb-T000005

(Preparation of negative electrode)
Using the obtained sample H, comparative sample I, and comparative sample J, an electrode was produced by the following method. That is, a 10 μm-thick stainless steel foil having nickel coated on the surface is used as an electrode current collector, composite particles or Si particles, acetylene black, and a polyimide as a binder (more precisely, a precursor of polyimide) The mixture was mixed at 80: 5: 15 (% by weight) using a planetary kneader to prepare a slurry. NMP was used as the solvent. First, NMP, which is a solvent, was added to the composite particles or Si particles and acetylene black and kneaded. Next, a polyimide precursor and NMP were added and mixed with a kneader. The kneading conditions were such that the number of rotations was 2000 rpm, 5 minutes, and kneading was performed 7 times including solid kneading. Next, the slurry was apply | coated to the electrical power collector using the blade method. The operation speed of the blade was 10 mm / sec. NMP was vaporized by drying at 50 ° C. for 1 hour under air. Next, in order to imidize the polyimide precursor, a heat treatment was performed at 400 ° C. for 5 hours in a nitrogen atmosphere.

The negative electrodes produced using Sample H, Comparative Sample I, and Comparative Sample J as described above are referred to as Negative Electrode H, Comparative Negative Electrode I, and Comparative Negative Electrode J, respectively.

The loading amount of the sample in each negative electrode is as follows. That is, the loading amount of the sample H in the negative electrode H is 0.918 mg / cm 2 , the loading amount of the comparative sample I in the comparative negative electrode I is 0.829 mg / cm 2 , and the carrying amount of the comparative sample J in the comparative negative electrode J is 0.707 mg / cm 2 .

(Manufacture of cells)
Next, a half cell was prepared using the negative electrode H, the comparative negative electrode I, and the comparative negative electrode J prepared as described above. For the evaluation of the characteristics, a coin type storage battery of CR2032 type (diameter 20 mm, height 3.2 mm) was used. Metal lithium was used for the counter electrode and polypropylene was used for the separator. As the electrolytic solution, 1 mol / l LiPF6 was used as a solute, and EC and DEC were mixed at a volume ratio of 3: 7 as a solvent. A half cell manufactured using the negative electrode H is referred to as a cell H, and a half cell manufactured using the comparative negative electrode I and the comparative negative electrode J is referred to as a cell I and a cell J, respectively.

(Cell measurement)
Next, measurement results of charge / discharge characteristics and cycle characteristics of the cells H to J manufactured as described above will be described.

Describe the measurement conditions for half-cells. The charging / discharging method was constant current-constant voltage charging at a rate of 0.2C, and constant current discharging at a rate of 0.2C. The upper limit voltage of charging / discharging was 1.5V, and the lower limit voltage was 0.01V. The measurement temperature was 25 ° C. Note that the rate of the active material containing silicon and titanium is calculated based on 4190 mAh / g per sample loading.

Further, in the measurement of cycle characteristics, a body stoppage time of 30 minutes or 2 hours was provided between any one charge / discharge and the next charge / discharge.

Table 6 shows the initial discharge capacity obtained as a result of charging and discharging of the cells F to H, the capacity maintenance ratio after 20 cycles with respect to the initial discharge capacity, and the capacity maintenance ratio after 50 cycles with respect to the initial discharge capacity. . FIG. 28 shows the transition of the capacity retention rate when the initial discharge capacity is 100%. The result of cell H is represented by a solid line, the result of cell I is represented by a dotted line, and the result of cell J is represented by a broken line. Note that the capacity retention rate of the cell J after 21 cycles is not described because it is being measured.

Figure JPOXMLDOC01-appb-T000006

According to Table 5 and FIG. 28, the cell H using the composite particles as the negative electrode active material which is the negative electrode for a power storage device of one embodiment of the present invention has a capacity higher than those of the cells I and J using silicon particles as the negative electrode active material. It can be seen that the maintenance rate is high. The reason why the capacity retention rate of the cell J is higher than that of the cell I is that the particle size of the comparative sample J is smaller than the particle size of the comparative sample I.

(Section observation of sample)
In FIG. 29, the result of having observed the cross section before and behind charge / discharge of the comparative sample I by STEM is shown. 29A is a cross-sectional image of the comparative sample I before being carried on the comparative negative electrode I, and FIG. 29B is a cross-sectional image of the comparative sample I taken out from the cell I after 50 cycles of charge / discharge. . FIG. 30 shows the result of observing the cross section of the sample H before and after charging and discharging with the STEM. 30A is a cross-sectional image of the sample H held on the negative electrode H, and FIG. 30B is a cross-sectional image of the sample H taken out from the cell H after 50 cycles of charge and discharge. 29A and 29B are cross-sectional images of different regions of the comparative sample I, respectively. Similarly, FIGS. 30A and 30B are cross-sectional images of different regions of the sample H, respectively.

In Comparative Sample I, the ends of the silicon particles 707 are altered into branches by repeating charging and discharging (see FIG. 29B), but in Sample H, alteration of the composite 703 is suppressed (FIG. 30). (See (B)). This indicates that the composite particles have the second region containing silicide, thereby relieving the stress and alteration caused by the volume change of the composite particles during charging and discharging.

In this example, the result of confirming the details of the composite particles included in Sample A to Sample E prepared in Example 1 by electron beam diffraction will be described.

As pretreatment, each sample was processed into a thin piece using FIB (Focused Ion Beam System: focused ion beam processing observation apparatus), and then a cross section was observed with a transmission electron microscope. Subsequently, electron diffraction (ED: Electron Diffraction) measurement was performed on two or three regions (about 0.3 μmφ) surrounded by a dotted line in each cross-sectional image.

(ED measurement result of sample A)
FIG. 31A shows a cross-sectional TEM observation result of the composite included in Sample A. FIG. FIGS. 31B, 31C, and 31D are electron beam diffraction measurement results in the regions a1, a2, and a3 in FIG. 31A, respectively. Regions a1 and a2 are regions observed in a striped pattern or a lattice pattern in FIG.

From the diffraction pattern of FIG. 31B, the lattice spacing (also referred to as d value) of the diffraction spot A is 0.225 nm, the d value of the diffraction spot B is 0.223 nm, and the d value of the diffraction spot C is 0.209 nm. I found out. It was also found that the face angle ∠AOB was 65 °, ∠BOC was 57 °, and ∠AOC was 122 °. The d value of (3 1 -1) obtained from [0 1 0] incidence of TiSi 2 (71-0187) in the database is 0.230 nm, the d value of (3 −1 1) is 0.229 nm, ( The d value of 0 -2 2) is 0.209 nm, ∠AOB is 67 °, ∠BOC is 56 °, and ∠AOC is 123 °.

By collating the value obtained from the result of FIG. 31B with the value in the database, it was suggested that the region a1 contains crystalline TiSi 2 .

Further, from the diffraction pattern of FIG. 31C, it was found that the d value of the diffraction spot A was 0.254 nm, the d value of the diffraction spot B was 0.184 nm, and the d value of the diffraction spot C was 0.225 nm. . It was also found that the surface angle ∠AOB was 53 °, ∠BOC was 45 °, and ∠AOC was 98 °. Moreover, d value of (2 1 -2) obtained from [0 1 0] incidence of TiSi 2 (71-0187) in the database is 0.252 nm, d value of (3 −1 -3) is 0.182 nm, The d value of (1-2-1) is 0.221 nm, ∠AOB is 54 °, ∠BOC is 46 °, and ∠AOC is 100 °.

By collating the value obtained from the result of FIG. 31C with the value of the database, it was suggested that the region a2 contains crystalline TiSi 2 .

On the other hand, since the diffraction pattern in FIG. 31D is mainly a halo pattern, the region a3 is considered to have low crystallinity. Further, from the XRD analysis results of the sample A shown in Example 1, TiSi 2 present in the sample A has a crystalline, Si has low crystallinity. Therefore, it is considered that the region a3 is likely to contain amorphous Si. In some cases, the region a3 includes amorphous silicide.

From the above results, in the cross-sectional TEM image of the composite of sample A, the region observed in a striped or lattice shape is the second region 112 containing crystalline silicide, and the other regions are made of amorphous Si. It is considered that the first region 111 includes the fourth region 114 including amorphous silicide.

(ED (Electron Diffraction) measurement result of sample B)
FIG. 32A shows a cross-sectional TEM observation result of the composite body included in Sample B. FIGS. 32B, 32C, and 32D show the results of electron beam diffraction measurement in the regions b1, b2, and b3 in FIG. 32A, respectively. Regions b1 and b2 are regions observed in a striped pattern or a lattice pattern in FIG.

From the diffraction pattern of FIG. 32B, it was found that the d value of the diffraction spot A was 0.25 nm, the d value of the diffraction spot B was 0.22 nm, and the d value of the diffraction spot C was 0.22 nm. Further, it was found that the surface angle ∠AOB was 55.0 °, ∠BOC was 57.4 °, and ∠AOC was 112.4 °. The d value of (1-1-1) obtained from [5 14] incidence of TiSi 2 (10-0225) in the database is 0.25 nm, and the d value of (1-50) is 0.22 nm, The d value of (0 -4 1) is 0.25 nm, ∠AOB is 55.6 °, ∠BOC is 54.8 °, and ∠AOC is 110.4 °.

By comparing the value obtained from the result of FIG. 32B with the value of the database, it was suggested that the region b1 contains crystalline TiSi 2 .

From the diffraction pattern of FIG. 32C, it was found that the d value of the diffraction spot A was 0.22 nm, the d value of the diffraction spot B was 0.15 nm, and the d value of the diffraction spot C was 0.22 nm. . Further, it was found that the surface angle ∠AOB was 44.8 °, ∠BOC was 43.9 °, and ∠AOC was 88.7 °. In addition, the d value of (1 3 -1) obtained from [5 1 8] incidence of TiSi 2 (10-0225) in the database is 0.22 nm, and the d value of (2 −2 −1) is 0.16 nm, The d value of (1 −50) is 0.22 nm, ∠AOB is 45.9 °, ∠BOC is 44.9 °, and ∠AOC is 90.8 °.

By collating the value obtained from the result of FIG. 32C with the value of the database, it was suggested that the region b2 contains crystalline TiSi 2 .

On the other hand, the diffraction pattern in FIG. 32D has a bright pattern, but mainly a halo pattern. Therefore, the region b3 is considered to have low crystallinity. From the XRD analysis result of Sample B shown in Example 1, TiSi 2 present in Sample B has crystallinity, and Si has low crystallinity. Therefore, it is considered that the region b3 is likely to contain amorphous Si. Note that the region b3 may include amorphous silicide.

Based on the above results, in the cross-sectional TEM image of the composite of sample B, the region observed in a striped or lattice shape is the second region 112 containing crystalline silicide, and the other regions contain amorphous Si. The first region 111 or the fourth region 114 containing amorphous silicide is considered.

(ED measurement result of sample C)
FIG. 33A shows a cross-sectional TEM observation result of the composite included in Sample B. 33B, 33C, and 33D show the results of electron beam diffraction measurement in the regions c1, c2, and c3 in FIG. 33A, respectively. The region c1 is a region observed in a stripe shape or a lattice shape in FIG.

From the diffraction pattern of FIG. 33B, it was found that the d value of the diffraction spot A was 0.19 nm, the d value of the diffraction spot B was 0.14 nm, and the d value of the diffraction spot C was 0.24 nm. Further, it was found that the surface angle ∠AOB was 33.8 °, ∠BOC was 44.6 °, and ∠AOC was 78.4 °. Moreover, d value of (0 6 -1) obtained from [7 1 6] incidence of TiSi 2 (10-0225) in the database is 0.19 nm, d value of (1 5 2) is 0.14 nm, (1 The d value of -1 1) is 0.25 nm, ∠AOB is 32.7 °, ∠BOC is 44.6 °, and ∠AOC is 77.3 °.

By comparing the value obtained from the result of FIG. 33B with the value of the database, it was suggested that the region c1 contains crystalline TiSi 2 .

On the other hand, although the diffraction pattern in FIG. 32C is mainly a halo pattern with a bright spot, and the diffraction pattern in FIG. 32D is also mainly a halo pattern, the regions c2 and c3 are crystalline. Is considered low. Further, from the XRD analysis results of the samples C shown in Example 1, TiSi 2 present in the sample C has a crystalline, Si has low crystallinity. Therefore, it is considered that the region c2 and the region c3 are likely to contain amorphous Si. Note that amorphous silicide may be included in the region c2 and / or the region c3.

From the above results, in the cross-sectional TEM image of the composite of sample C, the region observed in a striped or lattice shape is the second region 112 containing crystalline silicide, and the other regions contain amorphous Si. The first region 111 or the fourth region 114 containing amorphous silicide is considered.

(ED measurement result of sample D)
FIG. 34A shows a cross-sectional TEM observation result of the composite body included in Sample D. FIG. 34B and 34C show the results of electron beam diffraction measurement in the region d1 and the region d2 in FIG. 34A, respectively. The region d1 is a region observed in a stripe shape or a lattice shape in FIG.

From the diffraction pattern of FIG. 34B, it was found that the d value of the diffraction spot A was 0.21 nm, the d value of the diffraction spot B was 0.10 nm, and the d value of the diffraction spot C was 0.13 nm. It was also found that the face angle ∠AOB was 53.5 °, ∠BOC was 30.4 °, and ∠AOC was 83.9 °. Further, the d value of (1 0 -3) obtained from [3 9 1] incidence of WSi 2 (81-2168) in the database is 0.20 nm, the d value of (3 -10) is 0.10 nm, ( The d value of 2 −1 3) is 0.13 nm, ∠AOB is 53.2 °, ∠BOC is 29.9 °, and ∠AOC is 83.1 °.

By collating the value obtained from the result of FIG. 34B with the value of the database, it was suggested that the region d1 contains crystalline WSi 2 .

On the other hand, since the diffraction pattern in FIG. 34C is mainly a halo pattern, the region d2 is considered to have low crystallinity. Further, from the XRD analysis results of the sample D shown in Example 1, WSi 2 present in the sample D has a crystalline, Si has low crystallinity. Therefore, it is considered that the region d2 is likely to contain amorphous Si. Note that the region d2 may include amorphous silicide.

Based on the above results, in the cross-sectional TEM image of the composite of sample D, the region observed in a striped or lattice shape is the second region 112 containing crystalline silicide, and the other regions contain amorphous Si. The first region 111 or the fourth region 114 containing amorphous silicide is considered.

(ED measurement result of sample E)
FIG. 35A shows a cross-sectional TEM observation result of the composite included in Sample E. FIGS. 35B, 35C, and 35D are electron beam diffraction measurement results in region e1, region e2, and region e3 in FIG. 35A, respectively. Regions e1 and e2 are regions observed in a striped pattern or a lattice pattern in FIG.

From the diffraction pattern of FIG. 35B, it was found that the d value of the diffraction spot A was 0.64 nm, the d value of the diffraction spot B was 0.23 nm, and the d value of the diffraction spot C was 0.25 nm. Further, it was found that the surface angle ∠AOB was 71.3 °, ∠BOC was 19.9 °, and ∠AOC was 91.2 °. The d value of (0 0 1) obtained from [1 2 0] incidence of TaSi 2 (38-0383) in the database is 0.66 nm, the d value of (−2 1 1) is 0.22 nm, (− The d value of 2 1 0) is 0.24 nm, ∠AOB is 69.9 °, ∠BOC is 20.1 °, and ∠AOC is 90.0 °.

By collating the value obtained from the result of FIG. 35B with the value of the database, it was suggested that the region e1 contains crystalline TaSi 2 .

Further, from the diffraction pattern of FIG. 35C, it was found that the d value of the diffraction spot A was 0.23 nm, the d value of the diffraction spot B was 0.14 nm, and the d value of the diffraction spot C was 0.25 nm. . Further, it was found that the surface angle ∠AOB was 29.5 °, ∠BOC was 30.7 °, and ∠AOC was 60.2 °. Further, the d value of (1 1 −1) obtained from [1 2 3] incidence of TaSi 2 (38-0383) in the database is 0.22 nm, the d value of (3 0 −1) is 0.14 nm, ( 2 −10) is 0.24 nm, 0.2AOB is 29.9 °, ∠BOC is 32.1 °, and ∠AOC is 62.0 °.

By collating the value obtained from the result of FIG. 35C with the value of the database, it was suggested that the region b2 contains crystalline TaSi 2 .

On the other hand, since the diffraction pattern in FIG. 35D is mainly a halo pattern, the region e3 is considered to have low crystallinity. Moreover, from the XRD analysis result of the sample E shown in Example 1, TaSi 2 existing in the sample E has crystallinity, and Si has low crystallinity. Therefore, it is considered that the region e3 is likely to contain amorphous Si. Note that the region e3 may include amorphous silicide.

From the above results, in the cross-sectional TEM image of the composite of sample E, the region observed in a striped or lattice shape is the second region 112 containing crystalline silicide, and the other regions contain amorphous Si. The first region 111 or the fourth region 114 containing amorphous silicide is considered.

100 Negative electrode 101 Negative electrode current collector 102 Negative electrode active material layer 103 Composite 104 Conductive aid 105 Binder 106 Region 111 First region 112 Second region 113 Third region 114 Fourth region 200 Negative electrode 201 Negative electrode collection Electrode 202 Negative electrode active material layer 204 Graphene 300 Storage battery 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 400 Storage battery 402 Positive electrode 404 Negative electrode 500 Storage battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 Negative electrode 507 Separator 508 Electrolyte 509 Exterior body 510 Positive electrode lead electrode 511 Negative electrode lead electrode 512 Welding region 513 Curve 514 Sealing unit 600 Storage battery 601 Positive electrode cap 602 Battery can 603 Positive electrode terminal 604 Positive electrode 605 Separator 606 Negative electrode 607 Negative electrode terminal 608 Insulating plate 609 Insulating plate 611 PTC element 612 Safety valve mechanism 703 Composite 707 Silicon particle 900 Circuit board 910 Label 911 Terminal 912 Circuit 913 Power storage unit 914 Antenna 915 Antenna 916 Layer 917 Layer 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 951 Terminal 952 Terminal 981 Film 982 Film 990 Power storage device 991 Exterior body 992 Exterior body 993 Winding body 994 Negative electrode 995 Positive electrode 996 Separator 997 Lead electrode 998 Lead electrode 7100 Portable display device 7101 Housing 7102 Display unit 7103 Operation button 7104 Power storage device 7105 Lead electrode 7106 Current collector 7200 Portable information terminal 7201 Case 7202 Display unit 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output terminal 7207 Icon 7400 Mobile phone 7401 Case 7402 Display unit 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Power storage device 7408 Lead electrode 7409 Current collector 8021 Charging device 8022 Cable 8100 Car 8101 Headlight 8106 Electric motor

Claims (7)

  1. With a large number of particulate composites,
    The complex has a first region and a second region;
    The first region comprises amorphous silicon;
    The second region includes crystalline silicide,
    An end of the second region overlaps the first region;
    Negative electrode for power storage device.
  2. With a large number of particulate composites,
    The complex has a first region and a second region;
    The first region comprises amorphous silicon;
    The second region includes crystalline silicide,
    The second region has a region in contact with the first region at an end of the second region;
    In the vicinity of the edge of the second region, the crystallinity of the second region decreases as the distance from the first region decreases.
    Negative electrode for power storage device.
  3. In claim 1 or claim 2,
    The crystalline silicide includes any of titanium, tantalum, or tungsten.
    Negative electrode for power storage device.
  4. In claim 1 or claim 2,
    The thickness of the second region is 1 nm or more and 50 nm or less,
    Negative electrode for power storage device.
  5. In claim 3,
    The atomic ratio of silicon to any of titanium, tantalum, or tungsten is 2 times or more and 20 times or less,
    Negative electrode for power storage device.
  6. A power storage device having the negative electrode for a power storage device according to claim 1 or 2.
  7. Electrical equipment equipped with the power storage device according to claim 6.
PCT/IB2017/052547 2016-05-12 2017-05-03 Negative electrode to be used in power storage device, power storage device, and electrical device WO2017195071A1 (en)

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Publication number Priority date Publication date Assignee Title
WO2006129415A1 (en) * 2005-06-03 2006-12-07 Matsushita Electric Industrial Co., Ltd. Rechargeable battery with nonaqueous electrolyte and process for producing negative electrode
JP2009021046A (en) * 2007-07-10 2009-01-29 Panasonic Corp Positive electrode material for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery using the same, and method of manufacturing positive electrode material for nonaqueous electrolyte secondary battery
JP2009521792A (en) * 2005-12-23 2009-06-04 スリーエム イノベイティブ プロパティズ カンパニー Silicon-containing alloys useful for lithium-ion battery electrodes
JP2013253012A (en) * 2012-05-07 2013-12-19 Furukawa Electric Co Ltd:The Silicide combined silicon material and nonaqueous electrolyte secondary battery using the same
JP2014107132A (en) * 2012-11-28 2014-06-09 Furukawa Electric Co Ltd:The Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, lithium ion secondary battery, and method for producing negative electrode material for lithium ion secondary battery
JP2015125794A (en) * 2013-12-25 2015-07-06 古河電気工業株式会社 Composite particles and manufacturing method thereof, and negative electrode and nonaqueous electrolyte secondary battery using the same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006129415A1 (en) * 2005-06-03 2006-12-07 Matsushita Electric Industrial Co., Ltd. Rechargeable battery with nonaqueous electrolyte and process for producing negative electrode
JP2009521792A (en) * 2005-12-23 2009-06-04 スリーエム イノベイティブ プロパティズ カンパニー Silicon-containing alloys useful for lithium-ion battery electrodes
JP2009021046A (en) * 2007-07-10 2009-01-29 Panasonic Corp Positive electrode material for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery using the same, and method of manufacturing positive electrode material for nonaqueous electrolyte secondary battery
JP2013253012A (en) * 2012-05-07 2013-12-19 Furukawa Electric Co Ltd:The Silicide combined silicon material and nonaqueous electrolyte secondary battery using the same
JP2014107132A (en) * 2012-11-28 2014-06-09 Furukawa Electric Co Ltd:The Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, lithium ion secondary battery, and method for producing negative electrode material for lithium ion secondary battery
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