Electrode, secondary battery, and electronic device

Abstract

The present invention provides a conductive assistant which is used for the purpose of forming an active material layer having high electron conductivity with use of a small amount of the conductive assistant. The present invention provides an electrode for secondary batteries, said electrode comprising an active material layer that has high packing amount and high density with use of a small amount of a conductive assistant. In addition, the present invention provides a secondary battery which has high capacity per unit electrode volume. An electrode comprising an active material layer which contains a plurality of granular active materials and a plurality of fibrous carbon-containing compounds, wherein: the carbon-containing compounds are polymer compounds; and monomers of the polymer compounds include at least one substance that is selected from the group consisting of thiophene, benzene, pyol, aniline, phenol, phthalocyanine, furan, azulene and derivatives of these compounds.

Description

Technical Field

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. Alternatively, one aspect of the present invention relates to a process, a machine, a manufacture, or a composition of matter. One aspect of the present invention relates to an active material, an electrode, a positive electrode active material, a negative electrode active material, a positive electrode, a negative electrode, a secondary battery, and an electronic device having the secondary battery, which can be used in a secondary battery.

Background Art

[0002] With the remarkable spread of portable electronic devices such as mobile phones, smartphones, e-books, and portable game machines in recent years, the demand for miniaturization and large capacity of secondary batteries, which are their driving power sources, has been increasing. As secondary batteries used in portable electronic devices, secondary batteries typified by lithium-ion secondary batteries having advantages such as high energy density and large capacity are widely used.

[0003] Among secondary batteries, lithium-ion secondary batteries, which are widely popular due to their high energy density, include a positive electrode containing an active material such as lithium cobaltate (LiCoO 2 ), lithium iron phosphate (LiFePO 4 ), etc., a negative electrode made of a carbon material such as graphite capable of occluding and releasing lithium ions, and an electrolyte composed of a lithium salt such as LiBF 4 or LiPF 6 dissolved in an organic solvent such as ethylene carbonate or diethyl carbonate. The charge and discharge of a lithium-ion secondary battery are performed by lithium ions in the secondary battery moving between the positive electrode and the negative electrode through the non-aqueous electrolyte, and the lithium ions being inserted into and desorbed from the active materials of the positive electrode and the negative electrode.

[0004] A binder (also referred to as a binder) is mixed into the positive electrode or the negative electrode in order to bind between the active materials or between the active material and the current collector. Since the binder is generally a polymer organic compound such as insulating PVDF (polyvinylidene fluoride), its electron conductivity is extremely low. Therefore, if the ratio of the mixing amount of the binder to the amount of the active material is increased, the amount of the active material in the electrode relatively decreases, and as a result, the discharge capacity of the secondary battery decreases.

[0005] Therefore, by mixing a conductive aid such as acetylene black (AB) or graphite (carbon) particles, the electron conductivity between the active materials or between the active material and the current collector is improved. This enables the provision of a positive electrode active material with high electron conductivity (see Patent Document 1).

[0006] Patent Document 2 and Non-Patent Document 1 disclose a method for manufacturing a composite having a conductive polymer.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0008]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] In one aspect of the present invention, an object is to provide a conductive assistant for forming an active material layer having high electron conductivity with a small amount of the conductive assistant. Another object is to provide an electrode including an active material layer having a high filling amount and a high density with a small amount of the conductive assistant. Another object is to provide a battery having a large capacity per unit volume of the electrode. Another object is to provide a novel substance, active material particles, battery, secondary battery, power storage device, or a method for producing them.

Means for Solving the Problems

[0010] One aspect of the present invention is an electrode having a current collector and an active material layer, the active material layer having a plurality of granular active materials and a plurality of fibrous carbon-containing compounds, each of the plurality of fibrous carbon-containing compounds being a polymer compound, and the monomer of the polymer compound being at least one selected from the group consisting of thiophene, benzene, piol, aniline, phenol, phthalocyanine, furan, azulene, and derivatives thereof. As the carbon-containing compound of one aspect of the present invention, a polymer in which the monomer is at least one selected from the group consisting of thiophene, benzene, piol, aniline, phenol, phthalocyanine, furan, azulene, and derivatives thereof can be used.

[0011] In the above configuration, it is preferable that the average diameter of the plurality of fibrous carbon-containing compounds is 0.01 μm or more and 50 μm or less.

[0012] In the above configuration, it is preferable that the plurality of fibrous carbon-containing compounds are a network structure reaching the surface of the active material layer.

[0013] In the above configuration, having a current collector, the active material layer is provided on the current collector, and it is preferable that the network structure is in contact with the surface of the current collector.

[0014] In the above configuration, it is preferable that the active material is a lithium-containing composite oxide having an olivine-type crystal structure.

[0015] In the above configuration, the average particle size of the primary particles of the active material is preferably 50 nm or more and 500 nm or less.

[0016] Alternatively, one aspect of the present invention has a current collector and an active material layer, the active material layer has a plurality of granular active materials and a plurality of fibrous carbon-containing compounds, each of the plurality of fibrous carbon-containing compounds is a polymer compound, and the monomer of the polymer compound is at least one selected from the group consisting of thiophene, benzene, piol, aniline, phenol, phthalocyanine, furan, azulene, and derivatives thereof. The plurality of fibrous carbon-containing compounds are electrodes that are in contact with each other to form a path penetrating the active material layer.

[0017] In the above configuration, the average diameter of the plurality of fibrous carbon-containing compounds is preferably 0.01 μm or more and 50 μm or less.

[0018] In the above configuration, the active material is preferably a lithium-containing composite oxide having an olivine-type crystal structure.

[0019] In the above configuration, the average particle size of the primary particles of the active material is preferably 50 nm or more and 500 nm or less.

[0020] Alternatively, one aspect of the present invention has a current collector and an active material layer, the active material layer has a first aggregate in which the active material is aggregated, a second aggregate in which the active material is aggregated, and a plurality of fibrous carbon-containing compounds. The first aggregate and the second aggregate each have a plurality of primary particles, each of the plurality of fibrous carbon-containing compounds is a polymer compound, and the monomer of the polymer compound is at least one selected from the group consisting of thiophene, benzene, piol, aniline, phenol, phthalocyanine, furan, azulene, and derivatives thereof.

[0021] In the above configuration, the average diameter of the plurality of fibrous carbon-containing compounds is preferably 0.01 μm or more and 50 μm or less.

[0022] In the above configuration, it is preferable that the plurality of fibrous carbon-containing compounds are a network structure reaching the surface of the active material layer.

[0023] In the above configuration, it is preferable that the active material layer is provided on the current collector, and the network structure is in contact with the surface of the current collector.

[0024] In the above configuration, it is preferable that the active material is a lithium-containing composite oxide having an olivine-type crystal structure.

[0025] In the above configuration, it is preferable that the average particle diameter of the primary particles of the active material is 50 nm or more and 500 nm or less.

[0026] Or one aspect of the present invention is a secondary battery having the electrode described in any one of the above.

[0027] Or one aspect of the present invention is an electronic device equipped with the secondary battery described above.

Effect of the Invention

[0028] According to one aspect of the present invention, it is possible to provide a conductive auxiliary agent for forming an active material layer having high electron conductivity with a small amount of conductive auxiliary agent. Further, it is possible to provide an electrode including an active material layer having a high filling amount and high density with a small amount of conductive auxiliary agent. Further, by using the electrode, it is possible to provide a battery having a large capacity per electrode volume. Further, it is possible to provide a novel substance, active material particles, battery, secondary battery, power storage device, or a method for producing them.

Brief Description of the Drawings

[0029] FIG. 1A is a perspective view showing an electrode. FIG. 1B is a cross-sectional view of the active material layer. FIGS. 2A and 2B are cross-sectional views of the active material layer. FIG. 3 is a diagram showing an example of a carbon-containing compound. FIGS. 4A and 4B are cross-sectional views of the active material layer. FIGS. 5A and 5B are top views of the active material layer. FIG. 6A is a cross-sectional view of the active material layer. FIGS. 6B and 6C are diagrams for explaining an example of a method for producing the active material layer according to one aspect of the present invention. FIG. 7 is a flowchart showing an example of a method for producing the active material layer according to one aspect of the present invention. FIGS. 8A, 8B, and 8C are diagrams showing an example of graphene. FIGS. 9A, 9B, and 9C are diagrams for explaining the dispersed state in a polar solvent. FIGS. 10A and 10B are diagrams for explaining the dispersed state in a polar solvent. FIGS. 11A and 11B are diagrams for explaining a coin-shaped secondary battery. FIG. 12 is a diagram for explaining a laminated secondary battery. FIGS. 13A and 13B are diagrams for explaining a cylindrical secondary battery. FIG. 14 is a diagram for explaining an electronic device. FIGS. 15A, 15B, and 15C are diagrams for explaining an electronic device. FIGS. 16A and 16B are diagrams for explaining an electronic device. FIG. 17 is a diagram for explaining an electronic device. FIG. 18 is a diagram for explaining an electronic device.

BEST MODE FOR CARRYING OUT THE INVENTION

[0030] Hereinafter, embodiments will be described with reference to the drawings. However, it is easily understood by those skilled in the art that the embodiments can be implemented in many different modes, and the forms and details can be variously changed without departing from the spirit and scope thereof. Therefore, the present invention is not construed as being limited to the description of the following embodiments.

[0031] In each of the drawings described in this specification, the size, film thickness, or area of each component may be exaggerated for clarity. Therefore, it is not necessarily limited to that scale.

[0032] (Embodiment 1) In this embodiment, an electrode for a secondary battery according to one aspect of the present invention will be described.

[0033] Figure 1A is a perspective view of the electrode 200. In Figure 1A, the electrode 200 is shown in a rectangular sheet shape, but the shape of the electrode 200 is not limited to this, and any shape can be appropriately selected. The electrode 200 is manufactured by applying an electrode paste onto the current collector 201 and then drying it in a reducing atmosphere or under reduced pressure to form the active material layer 202. In Figure 1A, the active material layer 202 is formed only on one surface of the current collector 201, but the active material layer 202 may be formed on both surfaces of the current collector 201. Also, the active material layer 202 does not need to be formed on the entire surface of the current collector 201, and non-coated regions such as regions for connecting to the tabs of the electrode can be appropriately provided.

[0034] For the current collector 201, metals such as stainless steel, gold, platinum, zinc, iron, copper, aluminum, titanium, and alloys thereof, which have high conductivity and do not alloy with carrier ions such as lithium, can be used. Also, an aluminum alloy added with elements for improving heat resistance such as silicon, titanium, neodymium, scandium, molybdenum can be used. Also, it may be formed of a metal element that reacts with silicon to form a silicide. Examples of metal elements that react with silicon to form a silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The current collector 201 can appropriately use shapes such as foil, plate, sheet, net, punched metal, expanded metal. The current collector 201 is preferably one with a thickness of 10 μm or more and 30 μm or less.

[0035] Figure 1B is a schematic diagram showing a longitudinal section of the active material layer 202. The active material layer 202 includes granular active material 203, a carbon-containing compound 207 as a conductive assistant, and a binder (also referred to as a binder, not shown).

[0036] The active material 203 is a granular positive electrode active material composed of secondary particles having an average particle size and a particle size distribution, obtained by mixing raw material compounds in a predetermined ratio, firing the mixture, and then pulverizing, granulating, and classifying the fired product by appropriate means. Therefore, in Fig. 1B and the like, the active material 203 is schematically shown as a sphere, but it is not limited to this shape.

[0037] As the active material 203, a material capable of inserting and extracting lithium ions can be used.

[0038] In addition, when the carrier ion is an alkali metal ion or an alkaline earth metal ion other than lithium ion, as the positive electrode active material, in the above lithium compound and lithium-containing composite oxide, an alkali metal (for example, sodium, potassium, etc.) or an alkaline earth metal (for example, calcium, strontium, barium, beryllium, magnesium, etc.) may be used instead of lithium.

[0039] When the active material 203 is a positive electrode active material, for example, a lithium-containing composite oxide having an olivine-type crystal structure, a layered rock salt-type crystal structure, or a spinel-type crystal structure can be used.

[0040] Examples of the lithium-containing composite oxide having an olivine-type structure include composite oxides represented by the general formula LiMPO 4 (M is one or more of Fe(II), Mn(II), Co(II), Ni(II)). Representative examples of the general formula LiMPO 4 include LiFePO 4 , LiNiPO 4 , LiCoPO 4 , LiMnPO 4 , LiFe a Ni b PO 4 , LiFe a Co b PO 4 , LiFe a Mn b PO 4 , LiNi a Co b PO 4 、LiNia Mn b PO 4 (a + b is less than or equal to 1, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO 4 、LiFe c Ni d Mn e PO 4 、LiNi c Co d Mn e PO 4 (c + d + e is less than or equal to 1, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO 4 (f + g + h + i is less than or equal to 1, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc. can be mentioned.

[0041] In particular, LiFePO 4 is preferable because it well balances the requirements for a cathode active material, such as safety, stability, high capacity density, high potential, and the presence of lithium ions that can be extracted during initial oxidation (charging).

[0042] On the other hand, lithium-containing composite oxides with an olivine-type structure may have low electrical conductivity. Therefore, the output characteristics may be low in a secondary battery. By increasing the conductivity of the electrode with a conductive aid, the output characteristics can be improved. Also, for example, by reducing the primary particle size, the output characteristics can be improved.

[0043] According to one aspect of the present invention, excellent output characteristics can be realized in an electrode having a lithium-containing composite oxide with an olivine-type structure.

[0044] Examples of lithium-containing composite oxides having a layered rock salt-type crystal structure include lithium cobalt oxide (LiCoO 2 ), LiNiO 2 , LiMnO 2 , Li 2 MnO 3 , LiNi0.8 Co 0.2 O 2 such as NiCo-based (general formula: LiNi x Co 1-x O 2 (0 < x < 1)), LiNi 0.5 Mn 0.5 O 2 such as NiMn-based (general formula: LiNi x Mn 1-x O 2 (0 < x < 1)), LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O 2 such as NiMnCo-based (also referred to as NMC. General formula: LiNi x Mn y Co 1-x-y O 2 (x > 0, y > 0, x + y < 1)). Furthermore, Li(Ni 0.8 Co 0.15 Al 0.05 )O 2 , Li 2 MnO 3 -LiMO 2 (M = Co, Ni, Mn), etc. can also be mentioned.

[0045] In particular, LiCoO 2 is preferable because it has advantages such as a large capacity, is more stable in the air compared to LiNiO 2 , and is thermally more stable compared to LiNiO 2 .

[0046] Examples of lithium-containing composite oxides having a spinel-type crystal structure include, for example, LiMn 2 O 4 , Li 1+x Mn 2-x O 4 , LiMn 2-x Al x O 4 , LiMn 1.5 Ni 0.5 O 4 etc.

[0047] LiMn 2 O 4To a lithium-containing composite oxide having a spinel-type crystal structure containing manganese or the like, a small amount of lithium nickelate (LiNiO 2 or LiNi 1-x M x O 2 (M = Co, Al, etc.)) is mixed, which has advantages such as suppressing the elution of manganese and suppressing the decomposition of the electrolytic solution, and is preferable.

[0048] Further, as the positive electrode active material, a composite oxide represented by the general formula Li (2-j) MSiO 4 (M is one or more of Fe(II), Mn(II), Co(II), Ni(II), 0 ≦ j ≦ 2) can be used. Representative examples of the general formula Li (2-j) MSiO 4 include Li (2-j) FeSiO 4 , Li (2-j) NiSiO 4 , Li (2-j) CoSiO 4 , Li (2-j) MnSiO 4 , Li (2-j) Fe k Ni l SiO 4 , Li (2-j) Fe k Co l SiO 4 , Li (2-j) Fe k Mn l SiO 4 , Li (2-j) Ni k Co l SiO 4 , Li (2-j) Ni k Mn l SiO 4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m Ni n Co q SiO 4 , Li (2-j) Fe m Ni n Mn q SiO 4 , Li (2-j) Nim Co n Mn q SiO 4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn u SiO 4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. can be mentioned.

[0049] Also, as the positive electrode active material, A x M 2 (XO 4 ) 3 (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb, Al, X = S, P, Mo, W, As, Si) represented by the general formula can be used. As the NASICON type compound, Fe 2 (MnO 4 ) 3 , Fe 2 (SO 4 ) 3 , Li 3 Fe 2 (PO 4 ) 3 , etc. can be mentioned. Also, as the positive electrode active material, Li 2 MPO 4 F, Li 2 MP 2 O 7 , Li 5 MO 4 (M = Fe, Mn) represented by the general formula, perovskite type fluorides such as FeF 3 , metal chalcogenides (sulfides, selenides, tellurides) such as TiS 2 , MoS 2 , lithium-containing composite oxides having an inverse spinel type crystal structure such as LiMVO 4 , vanadium oxide systems (V 2 O 5 , V 6 O 13 , LiV 3 O 8 , etc.), manganese oxides, organic sulfur compounds, etc. can be used.

[0050] When the active material 203 is a negative electrode active material, a material capable of lithium dissolution / precipitation or lithium ion insertion / desorption can be used. For example, lithium metal, carbon-based materials, alloy-based materials, etc. can be mentioned.

[0051] Lithium metal has a low redox potential (-3.045 V with respect to the standard hydrogen electrode) and a large specific capacity per unit weight and volume (3860 mAh / g and 2062 mAh / cm 3 ) respectively, so it is preferable.

[0052] Examples of carbon-based materials include graphite, graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotubes, graphene, carbon black, etc.

[0053] Examples of graphite include artificial graphite such as mesocarbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite, and natural graphite such as spheroidized natural graphite.

[0054] Graphite shows a potential as low as that of lithium metal (0.1 - 0.3 V vs. Li / Li + ) when lithium ions are inserted into graphite (when forming a lithium-graphite intercalation compound). As a result, the lithium ion battery can exhibit a high operating voltage. Furthermore, graphite has advantages such as a relatively high capacity per unit volume, small volume expansion, low cost, and high safety compared to lithium metal, so it is preferable.

[0055] As the negative electrode active material, an alloy-based material capable of performing charge and discharge reactions through alloying and dealloying reactions with lithium can also be used. When the carrier ion is a lithium ion, examples of the alloy-based material include materials containing at least one of Al, Si, Ge, Sn, Pb, Sb, Bi, Ag, Zn, Cd, In, Ga, etc. Such elements have a large capacity compared to carbon, and in particular, silicon has a theoretically extremely high capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Examples of the alloy-based material using such elements include, for example, Mg 2 Si, Mg 2 Ge, Mg 2 Sn, SnS 2 , V 2 Sn 3 , FeSn 2 , CoSn 2 , 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, etc. can be mentioned.

[0056] Also, as the negative electrode active material, SiO, SnO, SnO 2 , titanium dioxide (TiO 2 ), lithium titanate (Li 4 Ti 5 O 12 ), lithium-graphite intercalation compound (Li x C 6 ), niobium pentoxide (Nb 2 O 5 ), tungsten oxide (WO 2 ), molybdenum oxide (MoO 2 ), etc. can be used.

[0057] Also, as the negative electrode active material, a lithium-transition metal double nitride, Li3 Li with an N-type structure 3-x 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.

[0058] When using a lithium-transition metal double nitride, since the negative electrode active material contains lithium ions, V that does not contain lithium ions can be used as the positive electrode active material 2 O 5 、Cr 3 O 8 and other materials can be combined, which is preferable. In addition, even when using a material containing lithium ions as the positive electrode active material, a lithium-transition metal double nitride can be used as the negative electrode active material by previously desorbing the lithium ions contained in the positive electrode active material.

[0059] Also, a material that causes a conversion reaction can be used as the negative electrode active material. For example, transition metal oxides that do not undergo an alloying reaction with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), may be used as the negative electrode active material. As materials that cause a conversion reaction, further, Fe 2 O 3 、CuO、Cu 2 O、RuO 2 、Cr 2 O 3 and other oxides, CoS 0.89 、NiS、CuS and other sulfides, Zn 3 N 2 、Cu 3 N、Ge 3 N 4 and other nitrides, NiP 2 、FeP 2 、CoP 3 and other phosphides, FeF 3 、BiF 3 and other fluorides also occur. Note that since the potential of the above fluorides is high, they may be used as the positive electrode active material.

[0060] In addition, the carbon-containing compound 207 added to the active material layer 202 as a conductive aid is preferably fibrous. Alternatively, the carbon-containing compound 207 is thread-like. Further, it is preferable that a plurality of carbon-containing compounds 207 are in contact with each other to form a conductive path. The conductive path formed by the plurality of carbon-containing compounds 207 is in contact with, for example, the active material 203. Further, the conductive path formed by the plurality of carbon-containing compounds 207 is preferably electrically connected to the active material 203. As the carbon-containing compound 207, vapor-grown carbon fiber (VGCF (registered trademark)) can be used. Alternatively, the carbon-containing compound 207 may be fibrous graphene, or the graphene may be curled to be like a carbon nanofiber. Or the carbon-containing compound 207 preferably has a conductive polymer described later.

[0061] The conductive path formed by one or more carbon-containing compounds 207 preferably contacts the surface of the current collector and reaches the surface of the active material layer 202. By the conductive path reaching from the surface of the current collector to the surface of the active material layer 202, the conductivity in the thickness direction of the active material layer 202 can be enhanced.

[0062] The conductive path formed by one or more carbon-containing compounds 207 can be dispersed in the active material layer 202 by branching. By enhancing the dispersibility of the carbon-containing compound 207, high conductivity can be achieved with a smaller amount of the carbon-containing compound 207, the weight ratio and volume ratio of the carbon-containing compound 207 in the active material layer 202 can be lowered, and the weight ratio and volume ratio of the active material 203 in the active material layer 202 can be increased. Therefore, the energy density of the secondary battery can be enhanced.

[0063] Further, as shown in FIG. 2A, aggregates 208 may be formed by a plurality of active materials 203. When aggregates 208 are formed by a plurality of active materials 203, for example, the strength of the active material layer 202 may increase. The strength of the active material layer 202 refers to, for example, the strength of resistance to a peeling test, or the suppression of the collapse of the active material from the active material layer 202 after charge and discharge, etc. Alternatively, when aggregates 208 are formed by a plurality of active materials 203, for example, the density of the active material layer 202 may be easily increased. By increasing the density of the active material layer 202, for example, the energy density of the secondary battery can be increased. An aggregate is, for example, an agglomerated portion formed by a plurality of active materials.

[0064] When a plurality of active materials 203 form aggregates, as shown in FIG. 2B for example, it is preferable that a plurality of carbon-containing compounds 207 form a conductive path that wraps around the aggregates 208. When the carbon-containing compound 207 wraps around the aggregates 208, the conductivity of the active material layer 202 may increase. Also, when the carbon-containing compound 207 wraps around the aggregates 208, the density of the active material layer 202 may increase. Further, when the carbon-containing compound 207 wraps around the aggregates 208, the strength of the active material layer 202 may increase. When the carbon-containing compound 207 wraps around the aggregates 208, there is also an effect of buffering the strain of the expansion and contraction of the positive electrode active material that occurs during charge and discharge. Thus, for example, the collapse of the active material layer is suppressed, and the cycle characteristics of the secondary battery are improved.

[0065] Alternatively, the carbon-containing compound 207 is preferably fibrous. Also, when the carbon-containing compound 207 is fibrous, the carbon-containing compound 207 may have branches. For example, the carbon-containing compound 207 has a resinous form with branches.

[0066] When the carbon-containing compound 207 is such that graphene is curled to be like a carbon nanofiber, for example, at the branched portion, three or more carbon nanofibers are connected, and the hexagonal shapes formed by carbon in the respective carbon nanofibers are connected and joined. At this time, the hexagonal shapes formed by carbon at the branched portion may be distorted.

[0067] As the carbon-containing compound included in the active material layer of one embodiment of the present invention, for example, a conductive polymer can be used. Examples of monomers of the conductive polymer include thiophene, benzene, pyrrole, aniline, phenol, phthalocyanine, furan, azulene, and derivatives thereof. More specifically, for example, 3,4-ethylenedioxythiophene, benzoquinone, etc. can be used. As described later, for example, the conductive polymer is formed by electrolytic polymerization of monomers. When monomers are bonded and grow by electrolytic polymerization, for example, the tip of growth may branch and grow. It is considered that the branching occurs, for example, when a plurality of monomers are bonded to the tip of growth.

[0068] The average diameter of the carbon-containing compound 207 is not particularly limited, but for example, it is preferably smaller than the particle diameter of the active material 203. For example, it is preferably 0.01 μm or more and 1 μm or less. Further, the length of the carbon-containing compound 207 is not particularly limited, but for example, it is preferably 1 μm or more and 300 μm or less. When the carbon-containing compound is resinous or fibrous, the diameter of the carbon-containing compound refers to, for example, the diameter of the cross section.

[0069] FIG. 3 shows an example in which the carbon-containing compound has a resinous form having branches. In FIG. 3, for example, the path length 211 from the branching point P to the next branching point Q is, for example, 1 μm or more and 300 μm or less.

[0070] FIG. 4A is a diagram showing an example in which the carbon-containing compound 207 does not form a conductive path reaching from the surface of the current collector to the surface of the active material layer 202 and is solidified and disposed in the middle part or the like of the active material layer 202. Further, in FIG. 4, a part of the carbon-containing compound 207 is not dispersed and forms an aggregate 209. When VGCF is used as the carbon-containing compound 207, for example, the carbon-containing compound 207 may be solidified and disposed in the middle part or the like of the active material layer 202 to form an aggregate 209.

[0071] FIG. 4B shows an example having a carbon-containing compound 207b (shown by a thick line for clarity) that forms a conductive path reaching from the surface of the current collector to the surface of the active material layer 202 in addition to the carbon-containing compound 207 (denoted as carbon-containing compound 207a for clarity in FIG. 4B) shown in FIG. 4A.

[0072] The active material layer of one aspect of the present invention may have, as the carbon-containing compound, one or more selected from graphene, VGCF, and AB in addition to the conductive polymer.

[0073] FIG. 5A is a schematic view showing the upper surface of the active material layer 202. In FIG. 5A, the carbon-containing compound 207 is arranged so as to cover a plurality of active materials 203.

[0074] As shown in FIG. 5B, the active material layer 202 may have graphene 204 in addition to the carbon-containing compound 207 as a conductive aid. As shown in FIG. 5B, a plurality of granular active materials 203 are covered by a plurality of graphenes 204. Graphene has a shape such as a flat plate shape or a sheet shape, for example. Further, graphene preferably has a bent shape. One sheet of graphene 204 is electrically connected to a plurality of granular active materials 203. Further, a plurality of granular active materials 203 may form an aggregate. Graphene 204 is preferably arranged so as to wrap the aggregate. Also, one sheet of graphene 204 is electrically connected to the plurality of granular active materials 203 included in the aggregate.

[0075] FIG. 6A is a view showing an example of a cross-section taken along the broken line A-B in FIG. 5B. Due to the bent shape of the graphene 204, it can make surface contact so as to enclose a part of the surface of the active material 203.

[0076] Since graphene 204 enables surface contact with low contact resistance, it is possible to improve the electron conductivity between the granular active material 203 and graphene 204 without increasing the amount of the conductive assistant. Also, a plurality of graphene 204s may be in surface contact. Further, graphene 204 does not necessarily overlap with other graphene only on the surface of the active material layer 202, and a part of graphene 204 is provided between a plurality of active material layers 202. Also, since graphene 204 is an extremely thin film (sheet) composed of a single layer of carbon molecules or a stack thereof, a part of its surface covers and contacts the surface of each granular active material 203 so as to follow it, and the portion not in contact with the active material 203 bends between a plurality of granular active materials 203, forming wrinkles, or is stretched and in a taut state.

[0077] Graphene 204 is formed, for example, by subjecting graphene oxide having an atomic ratio of oxygen to carbon of 0.405 or more to a reduction treatment.

[0078] Graphene oxide having an atomic ratio of oxygen to carbon of 0.405 or more can be produced using an oxidation method called the Hummers method.

[0079] In the Hummers method, a sulfuric acid solution of potassium permanganate, hydrogen peroxide solution, etc. are added to graphite powder to cause an oxidation reaction to produce a dispersion containing graphite oxide. In graphite oxide, functional groups such as epoxy groups, carbonyl groups, carboxyl groups, and hydroxyl groups are bonded due to the oxidation of the carbon in graphite. For this reason, the interlayer distance of a plurality of graphene layers becomes longer compared to graphite, and it becomes easier to form thin flakes by separating the layers. Next, ultrasonic vibration is applied to the dispersion containing graphite oxide to cleave the graphite oxide with a long interlayer distance and separate the graphene oxide, and a dispersion containing graphene oxide can be produced. Then, the solvent is removed from the dispersion containing graphene oxide to obtain powdery graphene oxide.

[0080] Here, graphene oxide with an atomic ratio of oxygen to carbon of 0.405 or more can be formed by appropriately adjusting the amount of an oxidizing agent such as potassium permanganate. That is, by increasing the amount of the oxidizing agent with respect to the graphite powder, the degree of oxidation of graphene oxide (the atomic ratio of oxygen to carbon) can be increased. Therefore, the amount of the oxidizing agent with respect to the raw material graphite powder may be determined according to the amount of graphene oxide to be produced.

[0081] Note that the production of graphene oxide is not limited to the Hummers method using a sulfuric acid solution of potassium permanganate. For example, the Hummers method using nitric acid, potassium chlorate, sodium nitrate, etc., or a method for producing graphene oxide other than the Hummers method may be appropriately used.

[0082] In addition, the thinning of the graphene oxide flakes may be performed not only by applying ultrasonic vibration but also by irradiating with microwaves, radio waves, or thermal plasma, or by applying physical stress.

[0083] The produced graphene oxide has epoxy groups, carbonyl groups, carboxyl groups, hydroxyl groups, etc. In a polar solvent typified by NMP, since the oxygen in the functional group is negatively charged, graphene oxide interacts with NMP while repelling different graphene oxides from each other and is difficult to aggregate. For this reason, in a polar solvent, graphene oxide is likely to be uniformly dispersed.

[0084] In addition, the length of one side of the graphene oxide (also referred to as the flake size) is 50 nm or more and 100 μm or less, preferably 800 nm or more and 20 μm or less. In particular, when the flake size is smaller than the average particle size of the granular active material 203, it becomes difficult to make surface contact with a plurality of active materials 203 and it also becomes difficult to connect the graphene to each other, so it becomes difficult to improve the electronic conductivity of the active material layer 202.

[0085] Figures 8A to 8C are diagrams showing examples of top views of graphene oxide of various shapes.

[0086] FIG. 8A is a diagram showing an example of the length 213 of one side of the graphene oxide 214. Also, as shown in FIG. 8B, in the top view of the graphene oxide 214, a minimum circle including the graphene oxide 214 may be created, and the diameter thereof may be defined as the length 213 of one piece. Further, as shown in FIG. 8C, it is preferable not to include the protrusion 212 in the length 213 of one piece.

[0087] The average particle size of the primary particles of the granular active material 203 is, for example, 10 nm or more and 100 μm or less. Also, by reducing the average particle size of the primary particles, the output characteristics of the secondary battery may be enhanced. As the positive electrode active material of one aspect of the present invention, those having a size of preferably 500 nm or less, more preferably 50 nm or more and 500 nm or less may be used.

[0088] In addition to typical polyvinylidene fluoride (PVDF), polyimide, polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene polymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc. can be used as the binder contained in the active material layer 202.

[0089] The active material layer 202 shown above preferably contains the active material 203, the conductive assistant, and the binder in proportions of 85 wt% or more and 94 wt% or less of the active material 203, 1 wt% or more and 5 wt% or less of the conductive assistant, and 1 wt% or more and 10 wt% or less of the binder, respectively, based on the total amount of the active material layer 202. Also, when both a conductive polymer and graphene are used as the conductive assistant, for example, it is preferable that the proportion of the conductive polymer is more than the proportion of graphene, and preferably 1.5 times or more.

[0090] The density of the active material layer is, for example, preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more of the density of the material used as the active material. When the active material layer of one aspect of the present invention uses LiFePO 4 the density of the active material layer is preferably 1.1 g / cm 3, more preferably 1.8 g / cm 3 or more, still more preferably 2.6 g / cm 3 or more.

[0091] <Example 1 of the production method> An example of the production method of the active material layer according to one aspect of the present invention is shown in the flowchart of FIG. 7.

[0092] As step S11, the active material 203, the monomer 221 of the carbon-containing compound, the binder 222, and the solvent 223 are prepared, and as step S12, they are mixed to prepare a slurry.

[0093] As the solvent, for example, one or more selected from non-polar solvents, protic polar solvents, aprotic polar solvents, etc. can be mixed and used. More specifically, for example, water, NMP (also referred to as N-methylpyrrolidone, 1-methyl-2-pyrrolidone, N-methyl-2-pyrrolidone, etc.) can be used as the solvent. Further, the solvent preferably has low solubility in the monomer of the carbon-containing compound.

[0094] Next, as step S13, the current collector 201 is prepared, and as step S14, the prepared slurry is coated on one surface of the current collector 201, and as step S15, a sample 224 having a first layer is formed on one surface of the current collector 201.

[0095] Next, as step S16, the solvent contained in the first layer is volatilized by heating, and as step S17, a sample 225 having a layer 231a is formed on one surface of the current collector 201. The heating may be performed in a reduced-pressure atmosphere.

[0096] Furthermore, the slurry may be applied to the other surface of the current collector 201, the solvent may be volatilized, and a layer 231b may also be formed on the other surface of the current collector 201.

[0097] Next, as step S18, the solution 226, the electrode 227, and the electrode 228 are prepared.

[0098] Solution 226 has a supporting electrolyte and a solvent. A monomer may also be dispersed in solution 226.

[0099] As the supporting electrolyte included in solution 226, known supporting electrolytes can be used. The supporting electrolyte includes, for example, alkali metal ions, alkaline earth metal ions, transition metal ions, pyridinium ions, imidazolium ions, quaternary phosphonium ions, etc. as cations. Also, the supporting electrolyte includes, for example, halogens, PF 6 ions, ClO 4 ions, AsF 6 ions, BF 4 ions, AlCl 4 ions, SCN ions, SO 4 ions, B 10 Cl 10 ions, B 12 Cl 12 ions, CF 3 SO 3 ions, C 4 F 9 SO 3 ions, C(CF 3 SO 2 ) 3 ions, C(C 2 F 5 SO 2 ) 3 ions, N(CF 3 SO 2 ) 2 ions, N(C 4 F 9 SO 2 )(CF 3 SO 2 ) ions, N(C 2 F 5 SO 2 ) 2 ions, etc. can be used.

[0100] Examples of the solvent included in the solution 226 include water, acetonitrile, nitrobenzene, hexane, toluene, diethyl ether, benzene, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolane, sultone, etc. One type of these solvents, or two or more of these solvents in any combination and ratio, can be used.

[0101] The electrodes 227 and 228 are preferably flat plates.

[0102] Next, the sample 225 is immersed in the solution 226. In the solution 226, as shown in an example in FIG. 6B, the electrodes 227 and 228 are preferably arranged substantially parallel to each other. Also, the current collector 201 included in the sample 225 is preferably arranged substantially parallel to the electrodes 227 and 228. Further, as shown in FIG. 6C, the electrode 200 may be arranged on the insulating mesh 232.

[0103] Next, as step S19, a voltage is applied between the electrode 227 and the electrode 228. A DC voltage is applied as the voltage. Alternatively, an AC voltage, for example, is applied as the voltage. The magnitude of the voltage and the frequency of the AC can be adjusted as appropriate to apply the voltage. By applying the voltage, the monomers of the carbon-containing compound included in the layers 231a and 231b are electrolytically polymerized to form a polymer. The polymer is preferably formed such that the fiber direction is along a direction substantially perpendicular to the surface of the current collector 201. Also, the polymer preferably forms a conduction path connecting the current collector 201 to the metal layer.

[0104] When an alternating voltage is applied to the electrodes 227 and 228, for example, when one of the positive and negative polarities (here, for example, a negative voltage) is applied to the electrode 227, the monomers included in the layer 231a are electrolytically polymerized to form a polymer. When one of the positive and negative polarities (here, for example, a negative voltage) is applied to the electrode 228, the monomers included in the layer 231b are electrolytically polymerized, for example.

[0105] Here, when a plurality of active materials 203 form the aggregate 208, as shown in an example in FIG. 2B, there is a possibility that the polymer grows by sewing between the aggregate 208 and the active material 203 or between a plurality of aggregates 208. In such a case, the growth of the polymer may be promoted. Also, there is a possibility that the polymer grows so as to enclose the aggregate 208.

[0106] Also, through the above steps, in step S20, the electrode 200 provided with the active material layer 202 having the conductive polymer can be obtained on both surfaces of the current collector 201, respectively.

[0107] In step S12 of the manufacturing method described above, in addition to the monomer of the carbon-containing compound, graphene oxide may be added as a material serving as a conductive aid. Since graphene oxide has functional groups, its dispersibility in the slurry is high.

[0108] Graphene oxide can be reduced, for example, by a heating process. For example, graphene oxide may be reduced by heating in step S16. Alternatively, by applying a voltage to cause a reduction reaction, graphene oxide can be reduced. For example, in step S15, it may be reduced by applying a voltage. Alternatively, it can be reduced by immersing it in a solution containing a reducing agent. For example, in step S15, by adding ascorbic acid, hydrazine, dimethylhydrazine, hydroquinone, sodium arsenide hydride (NaBH 4 ), LiAlH 4 , N,N-diethylhydroxylamine, etc. to the solution 1, graphene oxide may be reduced.

[0109] This embodiment can be implemented in appropriate combination with other embodiments.

[0110] (Embodiment 2) In this embodiment, graphene included in an electrode of a secondary battery according to an aspect of the present invention will be described.

[0111] Graphene is a carbon material having a crystal structure in which a hexagonal skeleton formed by carbon extends in a plane. Graphene is obtained by taking out a single atomic plane of a graphite crystal and has amazing characteristics in electrical, mechanical, or chemical properties. Therefore, high-mobility field-effect transistors, highly sensitive sensors, highly efficient solar cells, transparent conductive films for the next generation, etc. using graphene are expected to be applied in various fields and have attracted attention.

[0112] In this specification, graphene includes single-layer graphene or multi-layer graphene having 2 to 100 layers. Single-layer graphene refers to a sheet of a one-atomic-layer carbon molecule having a π bond. Further, graphene oxide refers to a compound obtained by oxidizing the above graphene. When graphene is formed by reducing graphene oxide, not all of the oxygen contained in graphene oxide is desorbed, and a part of the oxygen remains in the graphene. When oxygen is contained in graphene, the ratio of oxygen is 2 atomic% or more and 20 atomic% or less, preferably 3 atomic% or more and 15 atomic% or less of the entire graphene when measured by XPS.

[0113] Here, when the graphene is multi-layer graphene, by having graphene obtained by reducing graphene oxide, the interlayer distance of the graphene is 0.34 nm or more and 0.5 nm or less, preferably 0.38 nm or more and 0.42 nm or less, more preferably 0.39 nm or more and 0.41 nm or less. In ordinary graphite, the interlayer distance of single-layer graphene is 0.34 nm, and the graphene used in the secondary battery according to an aspect of the present invention has a longer interlayer distance, so that the movement of carrier ions between the layers of multi-layer graphene becomes easy.

[0114] The electrode for a secondary battery according to one aspect of the present invention disperses graphene so as to overlap in the active material layer and contact a plurality of active material particles. In other words, it can be said that a network for electron conduction by graphene is formed in the active material layer. As a result, the bonding of the plurality of active material particles is maintained, and as a result, an active material layer with high electron conductivity can be formed.

[0115] The active material layer added with graphene as a conductive assistant can be produced by the following method. First, after dispersing graphene in a dispersion medium (also referred to as a solvent), an active material is added and kneaded to produce a mixture. A binder (also referred to as a binder) is added to this mixture and kneaded to produce an electrode paste. Finally, after applying the electrode paste to a current collector, the dispersion medium is volatilized to produce an active material layer added with graphene as a conductive assistant.

[0116] Since graphene oxide has functional groups as compared with graphene, the dispersibility of graphene oxide in the slurry can be enhanced. FIG. 9A shows the structural formula of typical NMP as a dispersion medium. NMP100 is a compound having a 5-membered ring structure and is one of the polar solvents. As shown in FIG. 9A, the oxygen in NMP is electrically biased to the minus (-) side, and the carbon double-bonded to the oxygen is biased to the plus (+) side. Graphene, RGO or graphene oxide is added to such a polar diluting solvent.

[0117] As described above, graphene is a carbon crystal structure in which a hexagonal skeleton extends in a planar shape, and substantially no functional groups are contained in the structure. Further, RGO is obtained by reducing the originally possessed functional groups by heat treatment, and the proportion of functional groups in the structure is as low as about 10 wt%. Therefore, as shown in FIG. 9B, since the surface of graphene or RGO101 has no polarity, it exhibits hydrophobicity. For this reason, the interaction between NMP100 as a dispersion medium and graphene or RGO101 is extremely small, and rather, it is considered that graphene or RGO101 aggregates due to the interaction between graphene or RGO101 (see FIG. 9C).

[0118] On the one hand, graphene oxide 102 is a polar substance having functional groups such as epoxy groups, carbonyl groups, carboxyl groups, and hydroxyl groups. Since oxygen in the functional groups of graphene oxide 102 is negatively charged, it is difficult for different graphene oxides to aggregate in a polar solvent, while the interaction with NMP100, which is a polar solvent, is large (see Fig. 10A). Therefore, as shown in Fig. 10B, since functional groups such as epoxy groups of graphene oxide 102 interact with the polar solvent, aggregation of graphene oxides is inhibited, and as a result, it is considered that graphene oxide 102 is uniformly dispersed in the dispersion medium (see Fig. 10B).

[0119] From the above, in order to use graphene as a conductive assistant and construct a network having high electron conductivity in the active material layer, it is very effective to use graphene oxide having high dispersibility in the dispersion medium when preparing the electrode paste. The dispersibility of graphene oxide in the dispersion medium is considered to depend on the amount of functional groups having oxygen such as epoxy groups (which can also be said to be the oxidation degree of graphene oxide in another expression).

[0120] For this reason, one aspect of the present invention is graphene oxide used as a raw material for a conductive assistant used in an electrode for a secondary battery, and the graphene oxide has an atomic ratio of oxygen to carbon of 0.405 or more.

[0121] Here, the atomic ratio of oxygen to carbon is an index indicating the oxidation degree, and it is the ratio of the weights of carbon and oxygen among the constituent elements of graphene oxide based on carbon. The weights of the elements constituting graphene oxide can be measured, for example, by X-ray photoelectron spectroscopy (XPS).

[0122] The fact that the atomic number ratio of oxygen to carbon in graphene oxide is 0.405 or more means that, due to the high dispersibility of graphene oxide in a polar solvent, it has become a polar substance with sufficient bonding of functional groups such as epoxy groups, carbonyl groups, carboxyl groups, and hydroxyl groups.

[0123] Therefore, by dispersing and kneading graphene oxide with an atomic number ratio of oxygen to carbon of 0.405 or more together with an active material and a binder in a dispersion medium, applying it onto a current collector, and heating, an electrode for a secondary battery containing graphene with high dispersibility and an electron conduction network can be formed.

[0124] Graphene oxide preferably has a side length of 50 nm or more and 100 μm or less, more preferably 800 nm or more and 20 μm or less.

[0125] Moreover, one aspect of the present invention is an electrode for a secondary battery having an active material layer containing a plurality of granular active materials, a conductive aid containing a plurality of graphites, and a binder on a current collector, wherein the graphite is larger than the average particle size of the granular active material, the graphite is dispersed in the active material layer to the extent of making surface contact with one or more other adjacent graphites, and the graphite makes surface contact so as to wrap a part of the surface of the granular active material.

[0126] Moreover, one aspect of the present invention is an electrode for a secondary battery having an active material layer containing a plurality of granular active materials, a conductive aid containing a plurality of graphites, and a binder on a current collector, wherein the bonding state of carbon contained in the active material layer has a C = C bond ratio of 35% or more and a C - O bond ratio of 5% or more and 20% or less.

[0127] In addition, one aspect of the present invention is to disperse graphene oxide having an atomic ratio of oxygen to carbon of 0.405 or more in a dispersion medium, add an active material to the dispersion medium in which the graphene oxide is dispersed, and knead to produce a mixture. An electrode paste is produced by adding a binder to the mixture and kneading, the electrode paste is applied to a current collector, and after or simultaneously with volatilizing the dispersion medium contained in the applied electrode paste, the graphene oxide is reduced to form an active material layer containing graphene on the current collector. This is a method for manufacturing an electrode for a secondary battery.

[0128] When oxygen is contained in graphene, the ratio of oxygen is 2 atomic% or more and 20 atomic% or less, preferably 3 atomic% or more and 15 atomic% or less of the entire graphene when measured by XPS. The lower the ratio of oxygen, the higher the conductivity of graphene can be increased, and as a result, a network with high electron conductivity can be formed. In addition, the higher the ratio of oxygen, the more gaps serving as ion channels can be formed in graphene.

[0129] This embodiment can be implemented in appropriate combination with other embodiments.

[0130] (Embodiment 3) In this embodiment, the structure of the secondary battery will be described with reference to FIG. 11.

[0131] FIG. 11A is an external view of a coin-type (single-layer flat-type) secondary battery, and FIG. 11B is a cross-sectional view thereof.

[0132] The coin-type secondary battery 300 has a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal, which are insulated and sealed with a gasket 303 formed of polypropylene or the like. The positive electrode 304 is formed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact therewith. The negative electrode 307 is formed of a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact therewith. Between the positive electrode active material layer 306 and the negative electrode active material layer 309, there are a separator 310 and an electrolyte (not shown).

[0133] For at least one of the positive electrode 304 and the negative electrode 307, the electrode 200 shown in Embodiment 1 can be used.

[0134] As the separator 310, cellulose (paper) or an insulator such as polypropylene or polyethylene provided with pores can be used.

[0135] As the electrolyte, a material having carrier ions is used as the electrolyte. Representative examples of the electrolyte include LiClO 4 , LiAsF 6 , LiBF 4 , LiPF 6 , Li(C 2 F 5 SO 2 ) 2 N and other lithium salts. Further, an electrolyte having an anion exemplified as the anion of the supporting electrolyte included in the above-described solution 226 can be used.

[0136] When the carrier ions are alkali metal ions or alkaline earth metal ions other than lithium ions, as the electrolyte, in the above lithium salts, instead of lithium, an alkali metal (for example, sodium, potassium, etc.), an alkaline earth metal (for example, calcium, strontium, barium, beryllium, magnesium), etc. may be used.

[0137] In addition, as the solvent of the electrolytic solution, a material capable of moving carrier ions is used. As the solvent of the electrolytic solution, an aprotic organic solvent is preferred. Representative examples of aprotic organic solvents include ethylene carbonate (EC), propylene carbonate, dimethyl carbonate, diethyl carbonate (DEC), γ-butyrolactone, acetonitrile, dimethoxyethane, tetrahydrofuran, etc., and one or more of these can be used. In addition, by using a polymer material that gels as the solvent of the electrolytic solution, the safety against liquid leakage and the like is enhanced. Also, the secondary battery can be made thinner and lighter. Representative examples of the gelled polymer material include silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide-based gel, polypropylene oxide-based gel, gel of fluorine-based polymer, etc. Further, by using one or more ionic liquids (room temperature molten salts) that are flame-retardant and hardly volatile as the solvent of the electrolytic solution, even if the internal temperature rises due to internal short circuit or overcharging of the secondary battery, rupture or ignition of the secondary battery can be prevented.

[0138] Also, instead of the electrolytic solution, a solid electrolyte having an inorganic material such as a sulfide-based or oxide-based material, or a solid electrolyte having a polymer material such as a PEO (polyethylene oxide)-based material can be used. When using a solid electrolyte, it is not necessary to install a separator or a spacer. Also, since the entire battery can be solidified, the risk of liquid leakage is eliminated and the safety is dramatically improved.

[0139] For the positive electrode can 301 and the negative electrode can 302, metals such as nickel, aluminum, titanium, etc. that have corrosion resistance against liquids such as electrolytic solution during charge and discharge of the secondary battery, alloys of the metal, alloys of the metal and other metals (for example, stainless steel, etc.), laminates of the metal, laminates of the metal and the aforementioned alloys (for example, stainless steel / aluminum, etc.), laminates of the metal and other metals (for example, nickel / iron / nickel, etc.) can be used. The positive electrode can 301 is electrically connected to the positive electrode 304, and the negative electrode can 302 is electrically connected to the negative electrode 307, respectively.

[0140] These negative electrode 307, positive electrode 304, and separator 310 are impregnated with an electrolyte. As shown in FIG. 11B, with the positive electrode can 301 facing downwards, the positive electrode 304, separator 310, negative electrode 307, and negative electrode can 302 are laminated in this order, and the positive electrode can 301 and the negative electrode can 302 are crimped via a gasket 303 to manufacture a coin-shaped secondary battery 300.

[0141] Next, an example of a laminated secondary battery will be described with reference to FIG. 12.

[0142] The laminated secondary battery 500 shown in FIG. 12 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 electrolytic solution 508, and an exterior body 509. A separator 507 is installed between the positive electrode 503 and the negative electrode 506 provided in the exterior body 509. Further, the interior of the exterior body 509 is filled with the electrolytic solution 508.

[0143] In the laminated secondary battery 500 shown in FIG. 12, the positive electrode current collector 501 and the negative electrode current collector 504 also serve as terminals for obtaining electrical contact with the outside. Therefore, a part of the positive electrode current collector 501 and the negative electrode current collector 504 is arranged to be exposed to the outside from the exterior body 509.

[0144] In the laminated secondary battery 500, the exterior body 509 may be made of a three-layer laminated film in which a metal thin film with excellent flexibility such as aluminum, stainless steel, copper, or nickel is provided on a film made of a material such as polyethylene, polypropylene, polycarbonate, ionomer, or polyamide, and an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin is provided as the outer surface of the exterior body on the metal thin film. By adopting such a three-layer structure, permeation of the electrolytic solution and gas can be blocked, insulation can be ensured, and at the same time, resistance to the electrolytic solution can be achieved.

[0145] Next, an example of a cylindrical secondary battery will be described with reference to FIG. 13. As shown in FIG. 13A, the cylindrical secondary battery 600 has a positive electrode cap (battery lid) 601 on its upper surface and a battery can (outer can) 602 on its side surface and bottom surface. The positive electrode cap and the battery can (outer can) 602 are insulated by a gasket (insulating packing) 610.

[0146] FIG. 13B is a diagram schematically showing a cross-section of the cylindrical secondary battery. Inside the hollow cylindrical battery can 602, a battery element is provided in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 interposed therebetween. Although not shown, the battery element is wound around a center pin. One end of the battery can 602 is closed and the other end is open. For the battery can 602, metals such as nickel, aluminum, and titanium, alloys of the metals, alloys of the metals with other metals (for example, stainless steel, etc.), laminates of the metals, laminates of the metals and the above-mentioned alloys (for example, stainless steel / aluminum, etc.), laminates of the metals with other metals (for example, nickel / iron / nickel, etc.) that have corrosion resistance against liquids such as electrolytes during charging and discharging of the secondary battery can be used. Inside the battery can 602, the battery element in which the positive electrode, negative electrode, and 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 where the battery element is provided. The non-aqueous electrolyte can be the same as that used in coin-type or laminate-type secondary batteries.

[0147] The positive electrode 604 and the negative electrode 606 may be manufactured in the same manner as the positive and negative electrodes of the coin-shaped secondary battery described above. However, since the positive and negative electrodes used in the cylindrical secondary battery are wound, they are different in that the active material is formed on both sides of the current collector. A positive electrode terminal (positive current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative current collector 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 electrode terminal 603 is resistance welded to the safety valve mechanism 612, and the negative electrode 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 internal pressure of the battery rises above a predetermined threshold value. Further, the PTC element 611 is a thermal resistance element whose resistance increases when the temperature rises, and it limits the current amount due to the increase in resistance to prevent abnormal heat generation. For the PTC element, barium titanate (BaTiO 3 )-based semiconductor ceramics or the like can be used.

[0148] In addition, in the present embodiment, coin-shaped, laminate-shaped, and cylindrical secondary batteries are shown as secondary batteries, but secondary batteries of various shapes such as other sealed secondary batteries and square secondary batteries can be used. Further, a structure in which a plurality of positive electrodes, negative electrodes, and separators are stacked, or a structure in which a positive electrode, a negative electrode, and a separator are wound may be used.

[0149] The positive electrodes of the secondary batteries 300, 500, and 600 shown in the present embodiment use a positive electrode according to one aspect of the present invention. Therefore, the discharge capacities of the secondary batteries 300, 500, and 600 can be increased.

[0150] The present embodiment can be implemented in appropriate combination with other embodiments.

[0151] (Embodiment 4) The secondary battery according to one aspect of the present invention can be used as a power source for various electric devices driven by electric power.

[0152] Specific examples of electric devices using the secondary battery according to one aspect of the present invention include display devices such as televisions and monitors, lighting devices, desktop or notebook personal computers, word processors, image playback devices for playing still images or moving images stored on recording media such as DVDs (Digital Versatile Discs), portable CD players, radios, tape recorders, headphone stereos, stereos, table clocks, wall clocks, cordless phone handsets, transceivers, mobile phones, car phones, portable game machines, calculators, portable information terminals, electronic notebooks, electronic book terminals, electronic translators, voice input devices, video cameras, digital still cameras, toys, high-frequency heating devices such as electric shavers and microwave ovens, electric rice cookers, electric washing machines, electric vacuum cleaners, water heaters, fans, hair dryers, air conditioners, humidifiers, dehumidifiers and other air conditioning equipment, dishwashers, dish dryers, clothes dryers, futon dryers, electric refrigerators, electric freezers, electric refrigerator-freezers, DNA storage freezers, flashlights, power tools such as chain saws, medical devices such as smoke detectors and dialysis devices, etc. Further, industrial devices such as induction lamps, signal lights, belt conveyors, elevators, escalators, industrial robots, power storage systems, power storage devices for power leveling and smart grids, etc. are included. Also, moving bodies propelled by electric motors using the power from the secondary battery are also considered to be within the category of electric devices. Examples of the above moving bodies include electric vehicles (EVs), hybrid vehicles (HV) having both an internal combustion engine and an electric motor, plug-in hybrid vehicles (PHVs), track-laying vehicles obtained by changing the tire wheels of these into endless tracks, motorized bicycles including electric assist bicycles, motorcycles, electric wheelchairs, golf carts, small or large ships, submarines, helicopters, airplanes, rockets, artificial satellites, space exploration vehicles and planetary exploration vehicles, spaceships, etc.

[0153] Note that as a main power source for supplying almost all of the power consumption, a secondary battery according to an aspect of the present invention can be used for the above electrical equipment. Alternatively, when the supply of power from the main power source or the commercial power source stops, the secondary battery according to an aspect of the present invention can be used as an uninterruptible power source that can supply power to the electrical equipment. Alternatively, the secondary battery according to an aspect of the present invention can be used as an auxiliary power source for supplying power to the electrical equipment in parallel with the supply of power from the main power source or the commercial power source to the electrical equipment.

[0154] FIG. 14 shows a specific configuration of the above electrical equipment. In FIG. 14, the display device 700 is an example of an electrical equipment using a secondary battery 704 according to an aspect of the present invention. Specifically, the display device 700 corresponds to a display device for receiving TV broadcasts, and includes a housing 701, a display unit 702, a speaker unit 703, a secondary battery 704, and the like. The secondary battery 704 according to an aspect of the present invention is provided inside the housing 701. The display device 700 can receive power supply from a commercial power source, or can use the power stored in the secondary battery 704. Therefore, even when power supply from the commercial power source cannot be received due to a power outage or the like, the secondary battery 704 according to an aspect of the present invention can be used as an uninterruptible power source, making it possible to use the display device 700.

[0155] The display unit 702 can use a light-emitting device having a light-emitting element such as a liquid crystal display device, an organic EL element, etc. in each pixel, an electrophoretic display device, a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), a FED (Field Emission Display), etc., a semiconductor display device.

[0156] Note that the display device includes all display devices for information display, such as for personal computers and for advertising displays, in addition to those for receiving TV broadcasts.

[0157] In FIG. 14, the installed lighting device 710 is an example of an electrical device using the secondary battery 713 according to one aspect of the present invention. Specifically, the lighting device 710 includes a housing 711, a light source 712, a secondary battery 713, and the like. In FIG. 14, the case where the secondary battery 713 is provided inside the ceiling 714 on which the housing 711 and the light source 712 are installed is illustrated, but the secondary battery 713 may be provided inside the housing 711. The lighting device 710 can receive power supply from a commercial power source or use the power stored in the secondary battery 713. Therefore, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the secondary battery 713 according to one aspect of the present invention as an uninterruptible power supply, the lighting device 710 can be used.

[0158] Note that in FIG. 14, the installed lighting device 710 provided on the ceiling 714 is illustrated, but the secondary battery according to one aspect of the present invention can be used for installed lighting devices provided not only on the ceiling 714 but also on, for example, side walls 715, floors 716, windows 717, etc., or for desktop lighting devices.

[0159] In addition, as the light source 712, an artificial light source that artificially obtains light using power can be used. Specifically, incandescent bulbs, discharge lamps such as fluorescent lamps, and light emitting elements such as LEDs and organic EL elements can be cited as examples of the above artificial light sources.

[0160] In FIG. 14, an air conditioner having an indoor unit 720 and an outdoor unit 724 is an example of an electric device using a secondary battery 723 according to one aspect of the present invention. Specifically, the indoor unit 720 includes a housing 721, an air outlet 722, a secondary battery 723, and the like. In FIG. 14, the case where the secondary battery 723 is provided in the indoor unit 720 is illustrated, but the secondary battery 723 may be provided in the outdoor unit 724. Alternatively, the secondary battery 723 may be provided in both the indoor unit 720 and the outdoor unit 724. The air conditioner can receive power supply from a commercial power source or use the power stored in the secondary battery 723. In particular, when the secondary battery 723 is provided in both the indoor unit 720 and the outdoor unit 724, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the secondary battery 723 according to one aspect of the present invention as an uninterruptible power supply, the air conditioner can be used.

[0161] Note that in FIG. 14, a separate type air conditioner composed of an indoor unit and an outdoor unit is illustrated, but a secondary battery according to one aspect of the present invention can also be used in an integrated type air conditioner having the functions of the indoor unit and the outdoor unit in one housing.

[0162] In FIG. 14, an electric refrigerator-freezer 730 is an example of an electric device using a secondary battery 734 according to one aspect of the present invention. Specifically, the electric refrigerator-freezer 730 includes a housing 731, a refrigerator door 732, a freezer door 733, a secondary battery 734, and the like. In FIG. 14, the secondary battery 734 is provided inside the housing 731. The electric refrigerator-freezer 730 can receive power supply from a commercial power source or use the power stored in the secondary battery 734. Therefore, even when power supply from the commercial power source cannot be received due to a power outage or the like, by using the secondary battery 734 according to one aspect of the present invention as an uninterruptible power supply, the electric refrigerator-freezer 730 can be used.

[0163] Among the electrical appliances described above, high-frequency heating devices such as microwave ovens and electrical appliances such as electric rice cookers require high power in a short time. Therefore, by using the secondary battery according to one aspect of the present invention as an auxiliary power source to supplement the power that cannot be covered by the commercial power supply, it is possible to prevent the breaker of the commercial power supply from tripping when the electrical appliance is in use.

[0164] In addition, during the time period when the electrical appliance is not in use, particularly during the time period when the ratio of the actually used power amount to the total power amount that can be supplied by the commercial power supply source (referred to as the power usage rate) is low, by storing power in the secondary battery, it is possible to suppress the increase in the power usage rate outside the above time period. For example, in the case of the electric refrigerator-freezer 730, at night when the temperature is low and the opening and closing of the refrigerator door 732 and the freezer door 733 are not performed, power is stored in the secondary battery 734. Then, during the day when the temperature rises and the opening and closing of the refrigerator door 732 and the freezer door 733 are performed, by using the secondary battery 734 as an auxiliary power source, the power usage rate during the day can be kept low.

[0165] This embodiment can be implemented in appropriate combination with other embodiments.

[0166] (Embodiment 5) Next, a portable information terminal, which is an example of an electrical appliance, will be described with reference to FIG. 15.

[0167] FIGS. 15A and 15B show a foldable tablet-type terminal 800. FIG. 15A shows the open state, and the tablet-type terminal 800 has a housing 801, display units 802a, 802b, a display mode switching switch 803, a power switch 804, a power-saving mode switching switch 805, and an operation switch 807.

[0168] The display unit 802a can have a part as the touch panel area 808a, and data can be input by touching the displayed operation keys 809. In the display unit 802a, as an example, a configuration where half of the area has only a display function and the other half has a touch panel function is shown, but it is not limited to this configuration. A configuration where all areas of the display unit 802a have a touch panel function is also acceptable. For example, the entire surface of the display unit 802a can be made to display keyboard buttons to serve as a touch panel, and the display unit 802b can be used as a display screen.

[0169] Also, in the display unit 802b, similar to the display unit 802a, a part of the display unit 802b can be made into the touch panel area 808b. Also, by touching the position where the keyboard display switching button 810 of the touch panel is displayed with a finger or a stylus, etc., keyboard buttons can be displayed on the display unit 802b.

[0170] Also, touch input can be performed simultaneously on the touch panel area 808a and the touch panel area 808b.

[0171] Also, the display mode switching switch 803 can switch the display orientation such as vertical display or horizontal display, and can select switching between black and white display and color display, etc. The power saving mode switching switch 805 can optimize the display brightness according to the amount of external light detected by the optical sensor built in the tablet type terminal during use. The tablet type terminal may incorporate other detection devices such as sensors for detecting inclination such as gyroscopes and acceleration sensors in addition to the optical sensor.

[0172] Also, in FIG. 15A, an example where the display areas of the display unit 802b and the display unit 802a are the same is shown, but it is not particularly limited, and the size of one and the size of the other may be different, and the display quality may also be different. For example, one may be a display panel that can perform higher definition display than the other.

[0173] Figure 15B shows the closed state. The tablet terminal 800 includes a housing 801, a solar cell 811, a charge / discharge control circuit 850, a battery 851, and a DCDC converter 852. Note that in Figure 15B, a configuration having a battery 851 and a DCDC converter 852 is shown as an example of the charge / discharge control circuit 850. The battery 851 has a secondary battery described in the above embodiment.

[0174] Since the tablet terminal 800 is foldable in two, the housing 801 can be closed when not in use. Therefore, the display units 802a and 802b can be protected, and a tablet terminal 800 with excellent durability and reliability from the perspective of long-term use can be provided.

[0175] In addition, the tablet terminals shown in FIGS. 15A and 15B can also have functions such as displaying various information (still images, videos, text images, etc.), displaying a calendar, date, or time on the display unit, a touch input function for touch input operations or editing of the information displayed on the display unit, and a function of controlling processing by various software (programs).

[0176] Power can be supplied to the touch panel, display unit, video signal processing unit, etc. by the solar cell 811 mounted on the surface of the tablet terminal. Note that the solar cell 811 can be provided on one or both sides of the housing 801, and is suitable because it can be configured to efficiently charge the battery 851. When a secondary battery according to an aspect of the present invention is used as the battery 851, there are advantages such as size reduction.

[0177] Next, with reference to FIG. 15C, the configuration and operation of the charge / discharge control circuit 850 shown in FIG. 15B will be described with a block diagram. FIG. 15C shows a solar cell 811, a battery 851, a DCDC converter 852, a converter 853, switches SW1 to SW3, and a display unit 802. The battery 851, the DCDC converter 852, the converter 853, and the switches SW1 to SW3 correspond to the portions of the charge / discharge control circuit 850 shown in FIG. 15B.

[0178] First, an example of the operation when power is generated by the solar cell 811 due to external light will be described. The power generated by the solar cell is stepped up or down by the DCDC converter 852 so as to be a voltage for charging the battery 851. When the power from the solar cell 811 is used for the operation of the display unit 802, the switch SW1 is turned on, and the converter 853 steps up or down the voltage to the voltage required for the display unit 802. When the display unit 802 is not displaying, SW1 may be turned off and SW2 may be turned on to charge the battery 851.

[0179] Note that although the solar cell 811 is shown as an example of the power generation means, it is not particularly limited, and the battery 851 may be charged by other power generation means such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). For example, a contactless power transmission module that wirelessly (non-contact) transmits and receives power for charging, or a configuration that combines other charging means may be used.

[0180] Also, needless to say, if the secondary battery described in the above embodiment is provided, the electric device shown in FIG. 15 is not particularly limited.

[0181] This embodiment can be implemented in appropriate combination with other embodiments.

[0182] (Embodiment 6) Furthermore, an example of a moving body, which is an example of an electric device, will be described with reference to FIG. 16.

[0183] The secondary battery described in the previous embodiment can be used as a battery for control. The control battery can be charged by external power supply using plug-in technology or non-contact power feeding. In addition, when the moving body is a railway electric vehicle, it can be charged by power supply from an overhead wire or a conductive rail.

[0184] FIGS. 16A and 16B show an example of an electric vehicle. An electric vehicle 860 is equipped with a battery 861. The power of the battery 861 is adjusted by a control circuit 862 and supplied to a drive device 863. The control circuit 862 is controlled by a processing device 864 having a ROM, a RAM, a CPU, etc. (not shown).

[0185] The drive device 863 is configured by combining a DC motor or an AC motor alone, or a motor and an internal combustion engine. The processing device 864 outputs a control signal to the control circuit 862 based on input information such as the operation information (acceleration, deceleration, stop, etc.) of the driver of the electric vehicle 860 and the information during traveling (information such as uphill and downhill, load information applied to the drive wheels, etc.). The control circuit 862 adjusts the electric energy supplied from the battery 861 according to the control signal of the processing device 864 to control the output of the drive device 863. When an AC motor is installed, although not shown, an inverter for converting DC to AC is also built-in.

[0186] The battery 861 can be charged by external power supply using plug-in technology. For example, it is charged from a commercial power supply through a power plug to the battery 861. The charging can be performed by converting it to a DC constant voltage having a certain voltage value through a conversion device such as an AC / DC converter. By mounting the secondary battery according to one aspect of the present invention as the battery 861, it is possible to contribute to increasing the capacity of the battery and improving convenience. In addition, if the battery 861 itself can be reduced in size and weight due to the improvement of the characteristics of the battery 861, it contributes to reducing the weight of the vehicle, so the fuel efficiency can be improved.

[0187] Needless to say, if the secondary battery of one aspect of the present invention is provided, it is not particularly limited to the electronic devices shown above.

[0188] This embodiment can be implemented in appropriate combination with other embodiments.

[0189] (Embodiment 7) In this embodiment, an example of an uninterruptible power supply device is shown. The uninterruptible power supply device 8700 shown in FIG. 17 has at least a secondary battery, a protection circuit, a charge control circuit, and a neural network unit inside, and may have a mechanism for communicating by wire or wirelessly, a display panel 8702 for indicating an operating state, etc.

[0190] The power cord 8701 of the uninterruptible power supply device 8700 is electrically connected to the utility power supply 8703. The uninterruptible power supply device 8700 is electrically connected to the precision equipment 8704. The precision equipment 8704 refers to, for example, server equipment that does not want to be powered off. The uninterruptible power supply device 8700 connects a plurality of secondary batteries in series or in parallel to obtain a desired voltage (for example, 80V or more, 100V, or 200V, etc.).

[0191] The secondary battery of one aspect of the present invention can be used as the secondary battery.

[0192] The deterioration of the uninterruptible power supply device 8700 depends on various factors. When the user installs the uninterruptible power supply device 8700, for example, indoors or outdoors, the deterioration is also affected by the size of the room where it is installed, the temperature of the room, the temperature change of the installation environment, etc.

[0193] According to this embodiment, the deterioration of the secondary battery of the uninterruptible power supply device 8700 can be predicted periodically by AI (AI: Artificial Intelligence), and the user can determine the replacement timing based on the result.

[0194] In addition, by inputting data obtained periodically into the neural network unit and performing learning, feature amounts are extracted from the operations in the neural network processing, and the state of the secondary battery is analyzed more accurately.

[0195] For example, neural network processing can be used for predicting and detecting abnormal occurrences (specifically, micro short-circuit occurrences) in secondary batteries.

[0196] FIG. 18 shows an example of an aircraft. The aircraft 6500 shown in FIG. 18 has a propeller 6501, a camera 6502, a battery 6503, etc., and has a function of autonomous flight. As the battery 6503, a secondary battery according to an aspect of the present invention can be used. Since the secondary battery according to an aspect of the present invention has a high energy density, the flight distance of the aircraft 6500 can be increased. In addition, since the secondary battery according to an aspect of the present invention has excellent output characteristics, it is suitable for cases where high output characteristics are required, such as when the aircraft 6500 is accelerating.

[0197] For example, the image data captured by the camera 6502 is stored in the electronic component 6504. The electronic component 6504 can analyze the image data and detect the presence or absence of obstacles when moving. As the camera 6502, imaging devices of a plurality of types of systems may be used.

[0198] This embodiment can be implemented in appropriate combination with other embodiments.

Description of Reference Numerals

[0199] :100:NMP, 101:RGO, 102:Graphene oxide, 200:Electrode, 201:Current collector, 202:Active material layer, 203:Active material, 204:Graphene, 207:Carbon-containing compound, 208:Aggregate, 209:Aggregate, 211:Path length, 212:Protrusion, 213:Length of one side, 214:Graphene oxide, 221:Monomer, 222:Binder, 223:Solvent, 224:Sample, 225:Sample, 226:Solution, 227:Electrode, 228:Electrode, 231a:Layer, 231b:Layer, 300:Secondary 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, 500:Secondary 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 solution, 509:Outer package, 600:Secondary 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, 700:Display device, 701:Housing, 702:Display part, 703:Speaker part, 704:Secondary battery, 710:Lighting device, 711:Housing, 712:Light source, 713:Secondary battery, 714:Ceiling, 715:Side wall, 716:Floor, 717:Window, 720:Indoor unit, 721:Housing, 722:Air outlet, 723:Secondary battery, 724:Outdoor unit, 730:Electric refrigerator-freezer, 731:Housing, 732:Refrigerator door, 733:Freezer door, 734:Secondary battery, 800:Tablet terminal, 801:Housing, 802:Display part, 802a:Display part, 802b:Display part, 803:Switch, 804:Power switch, 805:Switch, 807:Operation switch, 808a:Area, 808b:Area, 809:Operation key, 810:Button, 811:Solar cell, 850:Charge and discharge control circuit, 851:Battery, 852:DC-DC converter, 853:Converter, 860:Electric vehicle, 861:Battery, 862:Control circuit, 863:Drive device, 864:Processing device, 8700:Uninterruptible power supply, 8701:Power cord, 8702:Display panel, 8703:System power supply, 8704:Precision equipment,

[0200]

Claims

1. It has a current collector and an active material layer provided on the current collector, The active material layer has a plurality of granular active materials and a plurality of fibrous carbon-containing compounds, Each of the plurality of fibrous carbon-containing compounds is a polymer compound, The monomer of the polymer compound is at least one selected from the group consisting of benzene, phenol, phthalocyanine, furan, azulene, and derivatives thereof, The plurality of fibrous carbon-containing compounds are a network structure reaching the surface of the active material layer, The network structure is an electrode in contact with the surface of the current collector.

2. It has a current collector and an active material layer provided on the current collector, The active material layer has a first aggregate in which the active material is aggregated, a second aggregate in which the active material is aggregated, and a plurality of fibrous carbon-containing compounds, Each of the first aggregate and the second aggregate has a plurality of primary particles, Each of the plurality of fibrous carbon-containing compounds is a polymer compound, The monomer of the polymer compound is at least one selected from the group consisting of benzene, phenol, phthalocyanine, furan, azulene, and derivatives thereof, The plurality of fibrous carbon-containing compounds are a network structure reaching the surface of the active material layer, The network structure is an electrode in contact with the surface of the current collector.

3. In Claim 1 or Claim 2, The active material is an electrode which is a lithium-containing composite oxide having an olivine-type crystal structure.

4. In any one of Claims 1 to 3, The average particle diameter of the primary particles of the active material is 50 nm or more and 500 nm or less, which is an electrode.

5. A secondary battery having the electrode according to any one of Claims 1 to 4.

6. An electronic device equipped with the secondary battery according to Claim 5.

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