JP7097690B2 - Electrodes and storage batteries - Google Patents

Description

The uniformity of the present invention relates to a product, a method, or a manufacturing method. Alternatively, the invention relates to a process, machine, manufacture, or composition (composition of matter). One aspect of the present invention relates to a method for manufacturing a semiconductor device, a display device, a light emitting device, a power storage device, a lighting device, or an electronic device. In particular, it relates to electronic devices and their operating systems.

In addition, in this specification, a power storage device refers to an element having a power storage function and a device in general. For example, it includes a storage battery (also referred to as a secondary battery) such as a lithium ion secondary battery, a lithium ion capacitor, an electric double layer capacitor, and the like.

Further, in the present specification, the electronic device refers to all devices having a power storage device, and an electro-optical device having a power storage device, an information terminal device having a power storage device, and the like are all electronic devices.

In recent years, various power storage devices such as lithium ion secondary batteries, lithium ion capacitors, and air batteries have been actively developed. In particular, high-output, high-capacity lithium-ion secondary batteries are portable information terminals such as mobile phones, smartphones, or notebook computers, portable music players, digital cameras, medical devices, hybrid electric vehicles (HEVs), and electric vehicles. Demand for (EV) or next-generation clean energy vehicles such as plug-in hybrid electric vehicles (PHEV) is rapidly expanding along with the development of the semiconductor industry, and it is becoming a modern computerized society as a source of rechargeable energy. It has become indispensable.

Currently, the characteristics required for lithium-ion secondary batteries include further increase in capacity, improvement in cycle characteristics, safety in various operating environments, and improvement in long-term reliability. In order to improve the cycle characteristics and increase the capacity of the lithium ion secondary battery, for example, improvement of the positive electrode active material has been studied (Patent Documents 1 and 2).

Further, at the same time as the demand for a power storage device such as a lithium ion secondary battery is expanding, the demand for a technique for rapidly charging the power storage device is increasing. For example, Patent Document 3 discloses a charging device capable of rapidly charging a power storage device mounted on an automobile.

Japanese Unexamined Patent Publication No. 2012-08914 Japanese Unexamined Patent Publication No. 2016-076454 Japanese Unexamined Patent Publication No. 2012-5341

Repeated charging and discharging of a lithium ion secondary battery, in particular, repeated rapid charging and discharging may cause a problem that the characteristics of the lithium ion secondary battery are deteriorated. The cause of this problem is that the positive electrode active material, which is one of the components of the positive electrode of the lithium ion secondary battery, may easily deteriorate as the lithium ion secondary battery is repeatedly charged and discharged. Can be mentioned.

More specifically, by rapidly charging and discharging the lithium ion secondary battery, lithium ions are rapidly inserted and removed from the positive electrode active material. As a result, the positive electrode active material may repeatedly expand and contract, deteriorate, and have a very small particle size. The positive electrode active material having such a small particle size deviates from the positive electrode, which causes deterioration of the cycle characteristics of the lithium ion secondary battery.

Further, in the lithium ion secondary battery, when the particle size of the deteriorated positive electrode active material is small enough to pass through the fine pores of the separator, the positive electrode active material passes through the fine pores of the separator and comes into contact with the negative electrode. As a result, a short circuit may occur. Further, the positive electrode active material having a smaller particle size may move in the power storage device and come into contact with the negative electrode through a portion not blocked by the separator due to being separated from the positive electrode, resulting in a short circuit.

Therefore, one aspect of the present invention is to provide a power storage device in which deterioration of cycle characteristics due to repeated rapid charging and discharging is suppressed. Alternatively, one aspect of the present invention is an object to enhance the safety of the power storage device. Another object of the present invention is to provide a power storage device having excellent charge / discharge characteristics.

Alternatively, one aspect of the present invention is to provide a new power storage device or a new lithium ion secondary battery.

The description of these issues does not preclude the existence of other issues. It should be noted that one aspect of the present invention does not need to solve all of these problems. It is possible to extract problems other than these from the description, drawings, and claims.

One aspect of the present invention has a current collector, an active material layer on the current collector, and a first protective layer, and the first protective layer is the active material layer and the current collector. The first protective layer is an electrode having a graphene compound.

In the electrode having the above configuration, it is more preferable that the current collector has one or more selected from iron, nickel, cobalt, titanium and tantalum.

In the electrodes having each of the above configurations, the active material layer has an active material and a second protective layer, the second protective layer surrounds the active material, and the second protective layer comprises the active material. It is more preferable to have a graphene compound.

Alternatively, one aspect of the present invention includes a first electrode and a second electrode, the first electrode being an electrode having each of the above configurations, and the first electrode being a positive electrode or a positive electrode. The second electrode functions as either one of the negative electrodes, and the second electrode is a power storage device that functions as either the positive electrode or the negative electrode.

Alternatively, one aspect of the present invention has a first electrode and a second electrode, and the first electrode and the second electrode are electrodes having the above-mentioned configurations, respectively, and the first electrode is used. The electrode is a power storage device that functions as either a positive electrode or a negative electrode, and the second electrode functions as either a positive electrode or a negative electrode.

Further, in one aspect of the present invention, a first mixture having an active material, a graphene compound and a first solvent is formed, and the first solvent is evaporated to form a second mixture, and the second mixture is formed. A method for producing an electrode, which comprises forming a third mixture having a mixture, a reducing agent and a second solvent, filtering the third mixture to recover the solid, and heating the solid.

Moreover, one aspect of the present invention is active by forming a first mixture having an active substance and a first solvent, providing the first mixture on a current collector, and evaporating the first solvent. A material layer is formed, a second mixture having a graphene compound and a second solvent is formed, the second mixture is provided on the current collector and the active material layer, and the second mixture is heated. This is a method for manufacturing an electrode.

Further, in the method for producing an electrode having the above configuration, it is more preferable to heat the second mixture at 400 ° C. or higher and 800 ° C. or lower under a nitrogen and hydrogen atmosphere.

Further, in one aspect of the present invention, a first mixture having an active material, a first graphene compound and a first solvent is formed, and the first solvent is evaporated to form a second mixture. A third mixture having the second mixture and the second solvent was formed, the third mixture was provided on the current collector, and the third mixture was heated to form an active material layer. Manufacture of an electrode that forms a fourth mixture with a second graphene compound and a third solvent, provides the fourth mixture on the current collector and the active material layer, and heats the fourth mixture. The method.

Further, in the method for producing an electrode having the above configuration, it is more preferable to heat the fourth mixture at 400 ° C. or higher and 800 ° C. or lower under a nitrogen and hydrogen atmosphere.

Moreover, one aspect of the present invention forms a first mixture having an active material, a first graphene compound and a first solvent, and evaporates the first solvent to form a second mixture. A third mixture having the second mixture, the reducing agent and the second solvent is formed, the third mixture is filtered to recover the solid, and the fourth having the solid and the second solvent. A fifth mixture having a second graphene compound and a third solvent is formed by forming a mixture of the above, providing the fourth mixture on a current collector, and heating the fourth mixture to form an active material layer. This is a method for producing an electrode in which a mixture of the above is formed, the fifth mixture is provided on the current collector and the active material layer, and the fifth mixture is added.

Further, in the method for producing an electrode having the above configuration, it is more preferable to heat the fifth mixture at 400 ° C. or higher and 800 ° C. or lower under a nitrogen and hydrogen atmosphere.

According to one aspect of the present invention, it is possible to provide a power storage device in which deterioration of cycle characteristics due to repeated rapid charging and discharging is suppressed. Further, according to one aspect of the present invention, the safety of the power storage device can be enhanced. Further, according to one aspect of the present invention, it is possible to provide a power storage device having excellent charge / discharge characteristics.

Alternatively, according to one aspect of the present invention, a novel power storage device or a novel lithium ion secondary battery can be provided.

The description of these effects does not preclude the existence of other effects. It should be noted that one aspect of the present invention does not necessarily have to have all of these effects. It should be noted that the effects other than these are self-evident from the description of the description, drawings, claims, etc., and it is possible to extract the effects other than these from the description of the description, drawings, claims, etc. Is.

A front view and a sectional view for explaining one aspect of the present invention. The figure explaining a part of the cross section of an electrode. The flowchart for demonstrating one aspect of this invention. The flowchart for demonstrating one aspect of this invention. The figure explaining the storage battery. The figure explaining the sectional view of the storage battery. The figure explaining the manufacturing method of the storage battery. The figure explaining the manufacturing method of the storage battery. The figure explaining the storage battery. The figure explaining the radius of curvature of a surface. The figure explaining the radius of curvature of a film. The figure explaining the coin type storage battery. The figure explaining the cylindrical storage battery. The figure explaining a part of the sectional view of the storage battery. The figure explaining a part of the sectional view of the storage battery. The figure explaining a part of the sectional view of the storage battery. The figure which shows an example of a storage battery. The figure which shows an example of a storage battery. The figure for demonstrating the example of a power storage system. The figure for demonstrating the example of a power storage system. The figure for demonstrating the example of a power storage system. The figure explaining an example of an electronic device. The figure explaining an example of an electronic device. The figure explaining an example of an electronic device. The figure explaining an example of an electronic device. Cross-sectional SEM image showing the active material layer. SEM image showing the side surface of the electrode.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that the form and details thereof can be changed in various ways. Further, the present invention is not limited to the description of the embodiments shown below.

(Embodiment 1)
In the present embodiment, the electrode which is one aspect of the present invention will be described with reference to FIGS. 1 to 4. In the present embodiment, in order to explain the electrode which is one aspect of the present invention, the electrode 50 will be described as an example.

<Electrode configuration>
FIG. 1A is a front view illustrating the electrode 50. FIG. 1B is an example of a cross-sectional view of the electrode 50 in the alternate long and short dash line A1-B1 shown in FIG. 1A. FIG. 1C is another example of a cross-sectional view of the electrode 50 in the alternate long and short dash line A1-B1 shown in FIG. 1A. Further, FIGS. 1 (D) and 1 (E) are enlarged views of the region 55 shown in FIGS. 1 (B) and 1 (C), respectively.

As shown in FIGS. 1A to 1C, the electrode 50 has a sheet-shaped current collector 51, a sheet-shaped active material layer 52, and a protective layer 53. In the electrode 50, the active material layer 52 is provided on the current collector 51. Further, in the electrode 50, the protective layer 53 is provided so as to surround both the active material layer 52 and the current collector 51. Further, the protective layer 53 is a layer having a function of transmitting carrier ions such as lithium ions.

As shown in FIG. 1B, the active material layer 52 may be provided on one surface of the sheet-shaped current collector 51. Further, as shown in FIG. 1C, the active material layer 52 may be provided on both surfaces of the sheet-shaped current collector 51.

A conductive material can be used for the current collector 51. In particular, it is preferable to use a material having conductivity and high heat resistance for the current collector 51 because it is possible to prevent deformation due to heat of the current collector 51 or deterioration due to heat. For example, when a material having high heat resistance is used for the current collector 51, even if the method for manufacturing the electrode 50 includes a step of heating the current collector 51 to a high temperature for forming a protective layer 53 or the like. It is preferable because it can prevent deformation or deterioration of the current collector 51.

Therefore, when the electrode 50 functions as the positive electrode of the power storage device, a metal such as iron, stainless steel, nickel, cobalt, and titanium, which is a conductive and highly heat-resistant material, and alloys thereof are used as a current collector. It is preferable to use it for 51. Alternatively, a metal such as gold, platinum, or aluminum, which is a conductive material, or an alloy thereof, or the like may be used for the current collector 51.

Further, when the electrode 50 functions as the negative electrode of the power storage device, a material that does not alloy with carrier ions such as lithium can be used for the current collector 51. Therefore, when the electrode 50 functions as a negative electrode of a power storage device, metals such as titanium and tantalum, which are materials that have conductivity, high heat resistance, and do not alloy with carrier ions such as lithium ions, and alloys thereof, etc. Is preferably used for the current collector 51. Alternatively, stainless steel, platinum, iron, copper or the like, which has conductivity and does not alloy with carrier ions such as lithium ions, may be used for the current collector 51.

As the current collector 51, a foil-like shape, a plate-like shape (sheet-like shape), a net-like shape, a columnar shape, a coil-like shape, a punching metal-like shape, an expanded metal-like shape, or the like can be appropriately used.

Further, a coating layer containing a fluorine compound may be provided on the surface of the current collector 51. As a result, the metal contained in the current collector 51 may be prevented from melting and diffusing.

Examples of the fluorine compound that can be used as the coating layer include titanium tetrafluoride (TiF ₄ ) and nickel difluoride (NiF ₂ ).

As shown in FIGS. 1B and 1C, the protective layer 53 is provided so as to surround the current collector 51 and the active material layer 52, thereby protecting the current collector 51 and the active material layer 52. It is possible to improve the durability of the electrode 50. Further, even when the active material 54 is deteriorated and the particle size becomes very small by repeating charging and discharging in the power storage device using the electrode 50, the particles are prevented from being separated from the active material layer. It can be suppressed. Therefore, it is possible to suppress deterioration of the cycle characteristics of the power storage device having the electrode 50 by repeating rapid charging and discharging. Further, since the particles can be prevented from passing through the separator and causing a short circuit, the safety of the power storage device can be enhanced.

Further, the protective layer 53 may be difficult to permeate substances other than carrier ions such as lithium ions. In the region surrounded by the protective layer 53, it may be possible to suppress the entry of substances other than carrier ions from other regions. In addition, it may be possible to suppress the release of substances other than carrier ions from the region surrounded by the protective layer 53 to other regions. Therefore, by providing the protective layer 53 so as to surround the current collector 51 and the active material layer 52, in a power storage device using the electrode 50, other than carrier ions are provided around the active material layer 52 from the outside of the protective layer 53. It is possible to suppress the entry of substances, and it may be possible to suppress the exit of substances other than carrier ions from the periphery of the active material layer 52 to the outside of the protective layer 53. Therefore, for example, even when a component of the active material layer 52 such as cobalt ion is dissolved, it may be possible to prevent the component from leaving the protective layer 53. Therefore, since it is possible to suppress a decrease in the concentration of the component in the region surrounded by the protective layer 53, it is possible to suppress further dissolution of the component of the active material layer 52. Therefore, it is possible to suppress the deterioration of the cycle characteristics of the power storage device using the electrode 50.

Further, as compared with the case where the protective layer 53 is provided only on the active material layer 52, when the protective layer 53 is provided so as to surround the current collector 51 and the active material layer 52, the protective layer 53 is provided with the electrode 50. It is difficult to peel off from the surface and is preferable.

The active material layer 52 has a particulate active material 54. When the electrode 50 has a positive electrode active material as the active material 54, the electrode 50 can function as a positive electrode of the power storage device. On the other hand, when the electrode 50 has a negative electrode active material as the active material 54, the electrode 50 can function as a negative electrode of the power storage device. The materials that can be used for the positive electrode active material and the negative electrode active material will be described later.

As shown in FIGS. 1D and 1E, the protective layer 53 preferably has a region in contact with the active material 54. In addition, in FIGS. 1B to 1D, the protective layer 53 is represented as a continuous layer or a continuous sheet, but as shown in FIG. 1E, the protective layer 53 is a plurality. It may be composed of a layer or a plurality of sheets. Even if the protective layer 53 is composed of a plurality of layers or a plurality of sheets, it may be observed on a continuous layer or in the form of a continuous sheet. Further, the protective layer 53 may enter the voids or the like of the active material layer 52.

Further, the active material layer 52 may have a protective layer 56 surrounding the active material 54. By surrounding the active material 54 with the protective layer 56, the surface of the active material 54 can be protected. Therefore, it is possible to suppress the deterioration of the active material 54 by repeating charging and discharging in the power storage device using the electrode 50. Further, even when the active material 54 is deteriorated and the particle size becomes very small, it is possible to prevent the particles from separating from the active material layer. Therefore, it is possible to suppress deterioration of the cycle characteristics of the power storage device having the electrode 50 by repeating rapid charging and discharging. Further, since the particles can be prevented from passing through the separator and causing a short circuit, the safety of the power storage device can be enhanced.

Further, since the protective layer 56 surrounds the active material 54, the region where the active material 54 and the electrolytic solution come into contact with each other in the power storage device using the electrode 50 becomes smaller, so that a side reaction between the active material 54 and the electrolytic solution occurs. It may be possible to suppress it.

FIG. 2 shows a cross-sectional view of the active material layer 52 when the protective layer 56 surrounding the active material 54 is provided. The active material layer 52 shown in FIG. 2 has a conductive auxiliary agent 62 and a binder 61 in addition to the active material 54 and the protective layer 56. The materials that can be used for the conductive auxiliary agent and the binder will be described later.

In FIG. 2, the active material 54 may have a region on its surface that comes into contact with other granular active material. Further, the active material 54 has a region on its surface that comes into contact with the conductive auxiliary agent 62. Further, the active material 54 has a region on the surface thereof that comes into contact with the binder 61. The surface of the active material 54 excluding these areas is partially or wholly covered with the protective layer 56. The protective layer 56 preferably covers the entire surface of the active material 54 except for the above region, but may be provided only on a part of the surface of the active material 54. Further, the plurality of active materials 54 have a region in contact with each other, are adjacent to each other via the conductive auxiliary agent 62, and are adjacent to each other via the conductive auxiliary agent 62 and the protective layer 56. It is bound by 61. Further, the active material layer 52 may have voids 63 formed by a plurality of active materials 54.

In addition, in this specification and the like, it can be said that the active material layer 52 is a complex.

When a layer having a conductive material is used for the protective layer 53 and the protective layer 56, a conductive path can be formed in the active material layer 52. By forming the conductive path in the active material layer 52, the discharge capacity of the power storage device using the electrode 50 can be improved. As the conductive material that can be used for the protective layer 53 and the protective layer 56, for example, a graphene compound is preferably used.

[Graphene compound]
Here, the graphene compound that can be used for the protective layer 53 and the protective layer 56 will be described.

A graphene compound is a compound in which graphene or multigraphene is modified into an atomic group having an atom other than carbon or an atom other than carbon. Further, the graphene compound may be a compound in which graphene or multigraphene is modified into an atomic group mainly composed of carbon such as an alkyl group and an alkylene.

Here, graphene is an arrangement of carbon atoms in one atomic layer, and has a π bond between carbon atoms. A stack of two or more layers and 100 or less layers of graphene may be referred to as multi-graphene. Graphene and multigraphene have, for example, a length of a major axis in the longitudinal direction or in a plane of 50 nm or more and 100 μm or less, or 800 nm or more and 50 μm or less.

The atomic group that modifies graphene or multigraphene may be referred to as a substituent, a functional group, a characteristic group, or the like. Here, in the present specification and the like, the modification means graphene, multigrafene, graphene compound, or graphene oxide (described later), an atom other than carbon, an atom group other than carbon, by a substitution reaction, an addition reaction or other reaction. Or it means introducing an atomic group having an atom other than carbon.

As an example of graphene or multigrafene modified to an atom other than carbon or an atom group having an atom other than carbon, there is graphene or multigraphene modified to oxygen or a functional group containing oxygen. Here, examples of the functional group containing oxygen include an epoxy group, a carbonyl group, a carboxyl group, a hydroxyl group and the like. Graphene compounds modified with oxygen or a functional group having oxygen may be referred to as graphene oxide. Further, in the present specification, graphene oxide also includes a multi-layered graphene oxide.

Graphene oxide can be obtained by oxidizing the above graphene or multigraphene. Alternatively, graphene oxide can be obtained by separating graphite oxide. Graphite oxide can be obtained by oxidizing graphite. Here, graphene oxide may be further modified with the above-mentioned atoms or atomic groups.

Further, a compound obtained by reducing graphene oxide may be referred to as "RGO (Reduced Graphene Oxide)". In RGO, all the oxygen contained in graphene oxide may not be desorbed, and some oxygen or an atomic group containing oxygen may remain in a state of being bonded to carbon. For example, RGO may have a carbonyl group such as an epoxy group or a carboxyl group, or a functional group such as a hydroxyl group.

Even if the graphene compound is thin, it may have high conductivity, and the contact area between the graphene compounds or between the graphene compound and the active material can be increased by surface contact. Therefore, the conductive path can be efficiently formed even if the amount per volume is small.

On the other hand, the graphene compound can also be used as an insulator. For example, a graphene compound sheet can be used as a sheet-shaped insulator. Here, for example, graphene oxide may have higher insulating properties than unoxidized graphene compounds or RGOs. Further, the graphene compound modified into an atomic group may be able to enhance the insulating property depending on the type of the atomic group to be modified.

Further, the graphene compound modified into an atomic group may have high lithium ion conductivity depending on the type of the modified atomic group. For example, when the graphene compound contained in the protective layer 53 has insulating properties and lithium ion conductivity, it is possible to prevent the protective layer 53 from interfering with the permeation of lithium ions in the power storage device having the electrode 50. preferable. Further, when the graphene compound contained in the protective layer 56 has insulating property and lithium ion conductivity, it is possible to suppress a side reaction between the active material 54 and the electrolytic solution in the power storage device having the electrode 50. Therefore, it is preferable.

Further, in the present specification and the like, the graphene compound includes a graphene precursor. The graphene precursor refers to a substance used for producing graphene, and the graphene precursor may contain, for example, the above-mentioned graphene oxide, graphite oxide, or the like.

Graphene having an alkali metal or graphene having an element other than carbon such as oxygen may be referred to as a graphene analog. In the present specification and the like, the graphene compound also includes graphene analogs.

The above is a description of the graphene compound that can be used for the protective layer 53 and the protective layer 56.

The above is a description of the configuration of the electrode 50. Subsequently, a method for manufacturing the electrode 50 will be described.

<Method of forming the protective layer 56>
First, a method of forming the protective layer 56 surrounding the active material 54 will be described with reference to FIG.

[First step]
First, a first mixture containing the active material 54, the graphene compound and the solvent is formed (see FIG. 3 (T1)).

The solvent used in the first mixture is preferably a polar solvent. For example, one of water, methanol, ethanol, acetone, tetrahydrofuran (THF), N, N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), ethylene glycol, diethylene glycol and glycerin. Two or more kinds of mixed solutions can be used.

For the formation of the first mixture, for example, a kneader or the like may be used.

[Second step]
Next, the solvent contained in the first mixture is evaporated to form the second mixture (see FIG. 3 (T2)). As the solvent evaporates, the surface of the active material is coated with the graphene compound.

For example, the solvent can be evaporated by heating the first mixture at a temperature of 40 ° C. or higher and 170 ° C. or lower, preferably 60 ° C. or higher and 100 ° C. or lower, for 1 minute or longer and 15 hours or shorter. Further, it is more preferable that this step is performed in a reduced pressure atmosphere.

Here, the second mixture may be crushed using a mortar or the like to reduce the particle size. Further, a step of adjusting the particle size using a sieve or the like may be performed.

By performing the first step and the second step described above, the protective layer 56 having the graphene compound can be formed.

When the graphene compound is graphene oxide, in addition to the second heating in the second step, heating is carried out under a reduced pressure atmosphere or an inert atmosphere at 1 minute or more and 10 hours or less, and 100 ° C. or more and 300 ° C. or less. By doing so, graphene oxide may be reduced to produce RGO. Further, when the graphene compound contained in the protective layer 56 is graphene oxide, the graphene oxide can be reduced to RGO by performing the third and subsequent steps below.

In addition, this production method is not limited to reducing graphene oxide even when the graphene compound contained in the protective layer 56 is graphene oxide. Further, the present production method is not limited to performing the third and subsequent steps below even when the graphene compound contained in the protective layer 56 is graphene oxide.

[Third step]
Following the second step, a reducing agent and a solvent are added to the second mixture to form the third mixture (see FIG. 3 (T3)). At this time, a pH adjuster may be added. By forming a third mixture and stirring, the graphene compound contained in the protective layer 56 is reduced. Therefore, when the protective layer 56 has graphene oxide, graphene oxide is reduced to generate RGO.

As the reducing agent, ascorbic acid, hydrazine, dimethylhydrazine, hydroquinone, sodium borohydride (NaBH ₄ ), lithium aluminum hydride (LiAlH ₄ ), N, N-diethylhydroxylamine, or derivatives thereof may be used. can. In particular, ascorbic acid and hydroquinone are preferable in that they are highly safe and easy to use industrially because they have a weaker reducing power than hydrazine and sodium hydride.

As the solvent, a polar solvent can be used. It is not limited as long as it can dissolve the reducing agent. For example, one or a mixture of water, methanol, ethanol, acetone, THF, DMF, NMP, DMSO, ethylene glycol, diethylene glycol and glycerin can be used.

As the pH adjuster, various alkaline solutions or alkaline salts can be used, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, calcium carbonate or carbonic acid. Lithium or the like can be used.

[Fourth step]
The third mixture is then filtered to recover the solid (see FIG. 3 (T4)). At this time, the obtained solid substance may be washed with water, acetone or the like. At this time, the solid substance contains the active material 54 and the graphene compound, and the filtrate contains a reducing agent, a solvent, a pH adjuster and the like. Therefore, by filtering, the reducing agent, the solvent, the pH adjusting agent and the like can be removed, and only the active material 54 and the graphene compound can be recovered.

[Fifth step]
Next, the obtained solid material is heated under a reduced pressure atmosphere or an inert atmosphere (see FIG. 3 (T5)). This makes it possible to evaporate the solvent remaining in the solid matter. Further, even if the reduction reaction of the graphene compound in the third step has not sufficiently proceeded, the reduction reaction of the graphene compound can be promoted again by heating in this step.

By heating in a reduced pressure atmosphere at a temperature of 40 ° C. or higher and 300 ° C. or lower for 1 minute or longer and 10 hours or shorter, the solvent remaining on the solid substance can be evaporated and graphene oxide can be reduced.

The above is the method for forming the protective layer 56 that surrounds the active material 54.

<Method of manufacturing electrodes>
Next, a method of manufacturing the electrode 50 having the protective layer 53 will be described with reference to FIG.

[First step]
First, a first mixture containing the active material 54 and the solvent is formed (see FIG. 4 (S1)).

The solvent used in the first mixture is preferably a polar solvent. For example, any one or a mixture of two or more of water, methanol, ethanol, acetone, THF, DMF, NMP and DMSO can be used.

When a positive electrode active material is used as the active material 54, an electrode that functions as a positive electrode of a power storage device can be manufactured. Further, when the negative electrode active material is used as the active material 54, an electrode that functions as a negative electrode of the power storage device can be manufactured.

By using the active material 54 surrounded by the protective layer 56 as the active material 54, it is possible to manufacture the electrode 50 having the active material 54 surrounded by the protective layer 56.

Further, the first mixture may have a conductive auxiliary agent, a binder and the like in addition to the active material 54 and the solvent.

Materials that can be used as the positive electrode active material, the negative electrode active material layer, the conductive auxiliary agent, and the binder will be described later.

[Second step]
Next, the first mixture is provided on the current collector 51 (see FIG. 4 (S2)). As a method for providing the first mixture on the current collector 51, a roll coating method such as an applicator roll, a screen printing method, a doctor blade method, a spin coating method, a bar coating method, or the like can be applied. ..

As described above, a material having high heat resistance can be used for the current collector 51.

[Third step]
Next, the solvent contained in the first mixture is evaporated to form the active material layer 52 (see FIG. 4 (S3)).

For example, the solvent can be evaporated by heating at a temperature of 40 ° C. or higher and 170 ° C. or lower, preferably 60 ° C. or higher and 100 ° C. or lower, for 1 minute or longer and 10 hours or shorter.

[Fourth step]
Next, a second mixture containing the graphene compound and the solvent is formed (see FIG. 4 (S4)).

As the graphene compound, for example, graphene oxide can be used.

The solvent used in the second mixture is preferably a polar solvent. For example, any one or a mixture of two or more of water, methanol, ethanol, acetone, THF, DMF, NMP, DMSO, ethylene glycol, diethylene glycol and glycerin can be used.

[Fifth step]
Next, the second mixture is provided on the current collector 51 and the active material layer 52 (see FIG. 4 (S5)). As a method of providing the second mixture on the current collector 51 and the active material layer 52, the same method as the method of providing the first mixture on the current collector 51 is used, or a dip coating method or a casting method is used. Alternatively, an electrophoretic electrodeposition method or the like can be used.

Next, the second mixture is heated in an air atmosphere. As a result, the solvent contained in the fourth mixture evaporates and the protective layer 53 is formed.

For example, the solvent can be evaporated by heating at a temperature of 40 ° C. or higher and 170 ° C. or lower, preferably 60 ° C. or higher and 100 ° C. or lower, for 1 minute or longer and 10 hours or shorter.

[Sixth step]
Next, the current collector 51, the active material layer 52, and the protective layer 53 are heated under a nitrogen and hydrogen atmosphere (see FIG. 4 (S6)).

When the protective layer 53 has graphene oxide as a graphene compound, the graphene oxide contained in the protective layer 53 is reduced in the seventh step to generate RGO. Therefore, the protective layer 53, which is a layer having RGO as the graphene compound, is formed. However, this production method is not limited to reducing graphene oxide when the second mixture has graphene oxide as a graphene compound. If the second mixture has graphene oxide as a graphene compound, the graphene oxide may not be reduced.

Graphene oxide can be reduced by heating in a nitrogen and hydrogen atmosphere at a temperature of 400 ° C. or higher and 800 ° C. or lower for 1 minute or longer and 10 hours or shorter.

As described above, by using a material having high heat resistance for the current collector, it is possible to prevent deformation due to heat of the current collector, deterioration due to heat, and the like. Therefore, it is preferable that the current collector 51 can be prevented from being deformed or deteriorated even if it is heated at a high temperature as described in the sixth step.

The above is the description of the manufacturing method of the electrode 50.

<Material>
Next, the material contained in the electrode 50 will be described.

[Positive electrode active material]
As the positive electrode active material, for example, a layered rock salt type crystal structure, a composite oxide having a spinel type crystal structure, or the like can be used. Further, as the positive electrode active material, for example, a polyanion-based positive electrode material can be used. Examples of the polyanion-based positive electrode material include a material having an olivine type crystal structure, a pearcon type material, and the like. Further, as the positive electrode active material, for example, a positive electrode material having sulfur can be used.

Various composite oxides can be used as the positive electrode active material. For example, compounds such as LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li ₂ MnO ₃ , V ₂ O ₅ , Cr ₂ O ₅ , and MnO ₂ can be used.

As a material having a layered rock salt type crystal structure, for example, a composite oxide represented by LiMO ₂ can be used. The element M is preferably one or more selected from Co or Ni. LiCoO ₂ is preferable because it has advantages such as a large capacity, stability in the atmosphere, and relatively thermal stability. Further, the element M may have one or more selected from Al and Mn in addition to one or more selected from Co and Ni.

For example, LiNi _x Mn _y Coz O _w (x, y, _z and w are, for example, x = y = z = 1/3 or its vicinity, w = 2 or its vicinity) can be used. Further, for example, LiNi _x Mn _y Coz Ow (x, y, _z and _w are, for example, x = 0.8 or its vicinity, y = 0.1 or its vicinity, z = 0.1 or its vicinity, respectively, w = 2 or its vicinity) can be used. Further, for example, LiNi _x Mn _y Coz Ow (x, y, _z and _w are, for example, x = 0.5 or its vicinity, y = 0.3 or its vicinity, z = 0.2 or its vicinity, respectively, w = 2 or its vicinity) can be used. Further, for example, LiNi _x Mn _y Coz Ow (x, y, _z and _w are, for example, x = 0.6 or its vicinity, y = 0.2 or its vicinity, z = 0.2 or its vicinity, respectively, w = 2 or its vicinity) can be used. Further, for example, LiNi _x Mn _y Coz Ow (x, y, _z and _w are, for example, x = 0.4 or its vicinity, y = 0.4 or its vicinity, z = 0.2 or its vicinity, respectively, w = 2 or its vicinity) can be used.

The neighborhood is, for example, a value larger than 0.9 times the value and smaller than 1.1 times the value.

Materials in which a part of the transition metal or lithium contained in the positive electrode active material is replaced with one or more elements selected from Fe, Co, Ni, Cr, Al, Mg, etc., and Fe, Co, Ni, Cr, etc. in the positive electrode active material. A material doped with one or more elements selected from Al, Mg and the like may be used as the positive electrode active material.

Further, as the positive electrode active material, for example, a solid solution in which a plurality of composite oxides are combined can be used as the positive electrode active material. For example, a solid solution of LiNi _x Mn _y Coz O ₂ (x, y, _z > 0, x + y + z = 1) and Li ₂ MnO ₃ can be used as the positive electrode active material.

As a material having a spinel-type crystal structure, for example, a composite oxide represented by LiM ₂ O ₄ can be used. It is preferable to have Mn as the element M. For example, LiMn ₂ O ₄ can be used. Further, it is preferable to have Ni in addition to Mn as the element M because the discharge voltage of the secondary battery may be improved and the energy density may be improved. Further, a small amount of lithium nickelate (LiNiO ₂ or LiNi _1-x M _x O ₂ (M = Co, Al, etc.)) is added to a lithium-containing material having a spinel-type crystal structure containing manganese such as LiMn ₂ O ₄ . By mixing, the characteristics of the secondary battery can be improved, which is preferable.

For the positive electrode active material, for example, the average particle size of the primary particles is preferably 1 nm or more and 100 μm or less, more preferably 50 nm or more and 50 μm or less, and further preferably 1 μm or more and 30 μm or less. Further, it is preferable that the specific surface area is 1 m ² / g or more and 20 m ² / g or less. The average particle size of the secondary particles is preferably 5 μm or more and 50 μm or less. The average particle size can be measured by observation with an SEM (scanning electron microscope) or TEM, or by a particle size distribution meter using a laser diffraction / scattering method. The specific surface area can be measured by a gas adsorption method.

A conductive material such as a carbon layer may be provided on the surface of the positive electrode active material. By providing a conductive material such as a carbon layer, the conductivity of the electrode can be improved. For example, the coating of the carbon layer on the positive electrode active material can be formed by mixing a carbohydrate such as glucose at the time of firing the positive electrode active material. Further, as the conductive material, graphene, multigraphene, graphene oxide (GO: Graphene Oxide) or RGO (Reduced Graphene Oxide) can be used. Here, RGO refers to, for example, a compound obtained by reducing graphene oxide (GO).

A layer having one or more of oxides or fluorides may be provided on the surface of the positive electrode active material. The oxide may have a composition different from that of the positive electrode active material. Further, the oxide may have the same composition as the positive electrode active material.

As the polyanion-based positive electrode material, for example, a composite oxide having oxygen, an element X, a metal A, and a metal M can be used. The metal M is one or more of Fe, Mn, Co, Ni, Ti, V, Nb, the metal A is one or more of Li, Na, Mg, and the element X is S, P, Mo, W, As, Si. One or more.

As a material having an olivine type crystal structure, for example, a composite material (general formula LiMPO ₄ (M is one or more of Fe (II), Mn (II), Co (II), Ni (II)) can be used. can. Typical examples of the general formula LiMPO ₄ are 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 . LiNi _a Mn _b PO ₄ (a + b is 1 or less, 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 1 or less, 0 <c <1, 0 <d <1, 0 <e <1), LiFe _f Ni _g Coh Mn _i PO ₄ (f + g + _h + i is 1 or less, 0 <f <1, 0 < Lithium compounds such as g <1, 0 <h <1, 0 <i <1) can be used.

In particular, LiFePO ₄ is preferable because it satisfies the requirements for the positive electrode active material in a well-balanced manner, such as safety, stability, high capacity density, and the presence of lithium ions extracted during initial oxidation (charging).

For the positive electrode active material having an olivine type crystal structure, for example, the average particle size of the primary particles is preferably 1 nm or more and 20 μm or less, more preferably 10 nm or more and 5 μm or less, and 50 nm or more and 2 μm or less. More preferred. Further, it is preferable that the specific surface area is 1 m ² / g or more and 20 m ² / g or less. The average particle size of the secondary particles is preferably 5 μm or more and 50 μm or less.

Further, a composite material such as 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) is used. Can be used. Typical examples of the general formula Li _(2-j) MSiO ₄ are 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) Ni _m Con _n Mn _q SiO ₄ (m + n + q is 1 or less, 0 <m <1, 0 <n <1, 0 <q <1), Li _(2-j) Ferr Nis Cot Mn _u SiO ₄ ( _r + _s + _t + u is 1 or less, 0 <r <1, 0 <s <1, 0 <t <1, 0 <u <1) And other lithium compounds can be used as the material.

In addition, the general formula of A _x M ₂ (XO ₄ ) ₃ (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb, X = S, P, Mo, W, As, Si) The represented pearcon type compound can be used. Examples of the pear-con type compound include Fe ₂ (MnO ₄ ) ₃ , Fe ₂ (SO ₄ ) ₃ , Li ₃ Fe ₂ (PO ₄ ) ₃ and the like. Further, as the positive electrode active material, a compound represented by the general formula of Li ₂ MPO ₄ F, Li ₂ MP ₂ O ₇ , Li ₅ MO ₄ (M = Fe, Mn) can be used.

Further, as the positive electrode active material, a perovskite-type fluoride such as NaFeF ₃ , FeF ₃ , metal chalcogenides (sulfide, selenium, telluride) such as TiS ₂ and MoS ₂ , and a reverse spinel-type crystal structure such as LiMVO ₄ are used. Materials such as oxides, vanadium oxides (V ₂ O ₅ , V ₆ O ₁₃ , LiV ₃ O ₈ and the like), manganese oxides, organic sulfur compounds and the like can be used.

Further, as the positive electrode active material, a borate-based positive electrode material represented by the general formula LiMBO ₃ (M is Fe (II), Mn (II), Co (II)) can be used.

Further, as the positive electrode active material, a lithium manganese composite oxide that can be represented by the composition formula Li _a Mn _b M _{c Od} can be used. Here, as the element M, a metal element selected from other than lithium and manganese, silicon, and phosphorus are preferably used, and nickel is more preferable. Further, when measuring the entire particles of the lithium manganese composite oxide, it is necessary to satisfy 0 <a / (b + c) <2, c> 0, and 0.26 ≦ (b + c) / d <0.5 at the time of discharge. preferable. In order to develop a high capacity, it is preferable to use a lithium manganese composite oxide having a region having a different crystal structure, crystal orientation or oxygen content between the surface layer portion and the central portion. In order to obtain such a lithium manganese composite oxide, for example, 1.6 ≦ a ≦ 1.848, 0.19 ≦ c / b ≦ 0.935, and 2.5 ≦ d ≦ 3 are preferable. Further, it is particularly preferable to use the lithium manganese composite oxide represented by the composition formula of Li _1.68 Mn _0.8062 Ni _0.318 O ₃ . In the present specification and the like, the lithium manganese composite oxide represented by the composition formula of Li _1.68 Mn _0.8062 Ni _0.318 O ₃ is the ratio (molar ratio) of the amount of the raw material to Li ₂ CO ₃ . : MnCO ₃ : A lithium manganese composite oxide formed by setting NiO = 0.84: 0.8062: 0.318. Therefore, the lithium manganese composite oxide is represented by the composition formula Li _1.68 Mn _0.8062 Ni _0.318 O ₃ , but may deviate from this composition.

The composition of the metal, silicon, phosphorus, etc. of the entire particles of the lithium manganese composite oxide can be measured using, for example, ICP-MS (inductively coupled plasma mass spectrometer). Further, the oxygen composition of the entire particles of the lithium manganese composite oxide can be measured by using, for example, EDX (energy dispersive X-ray analysis method). Further, it can be obtained by using valence evaluation of molten gas analysis and XAFS (X-ray absorption fine structure) analysis in combination with ICP-MS analysis. The lithium-manganese composite oxide refers to an oxide containing at least lithium and manganese, and includes chromium, cobalt, aluminum, nickel, iron, magnesium, molybdenum, zinc, indium, gallium, copper, titanium, niobium, and silicon. And at least one element selected from the group consisting of phosphorus and the like may be contained.

When the carrier ion is an alkali metal ion other than lithium ion or an alkaline earth metal ion, the positive electrode active material is an alkali metal (for example, sodium or potassium) or an alkaline earth metal (for example) instead of lithium. , Calcium, strontium, barium, beryllium, magnesium, etc.) may be used. For example, a sodium-containing layered oxide can be used.

Materials having sodium include, for example, NaFeO ₂ , Na _2/3 [Fe _1/2 Mn _1/2 ] O ₂ , Na _2/3 [Ni _1/3 Mn _2/3 ] O ₂ , Na ₂ Fe ₂ ( SO ₄ ) ₃ , Na ₃ V ₂ (PO ₄ ) ₃ , Na ₂ FePO ₄ F, NaVPO ₄ F, NaMPO ₄ (M is Fe (II), Mn (II), Co (II), Ni (II). ), Na ₂ FePO ₄ F, Na ₄ Co ₃ (PO ₄ ) ₂ P ₂ O ₇ , and other sodium-containing oxides can be used as the positive electrode active material.

Further, as the positive electrode active material, a lithium-containing metal sulfide can be used. For example, Li ₂ TiS ₃ and Li ₃ NbS ₄ can be mentioned.

[Negative electrode active material]
As the negative electrode active material, for example, an alloy-based material, a carbon-based material, or the like can be used.

As the negative electrode active material, an element capable of performing a charge / discharge reaction by an alloying / dealloying reaction with lithium can be used. For example, a material containing at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium and the like can be used. Such elements have a larger capacity than carbon, and silicon in particular has a high theoretical capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Further, a compound having these elements may be used. For example, SiO, Mg ₂ Si, Mg ₂ Ge, SnO, SnO ₂ , 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 and the like. Here, an element capable of performing a charge / discharge reaction by an alloying / dealloying reaction with lithium, a compound having the element, and the like may be referred to as an alloy-based material.

In the present specification and the like, SiO refers to, for example, silicon monoxide. Alternatively, SiO can also be expressed as SiO _x . Here, x preferably has a value in the vicinity of 1. For example, x is preferably 0.2 or more and 1.5 or less, and preferably 0.3 or more and 1.2 or less.

As the carbon-based material, graphite, easily graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotubes, graphene, carbon black and the like may be used.

Examples of graphite include artificial graphite and natural graphite. Examples of the artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite and the like. Here, as the artificial graphite, spheroidal graphite having a spherical shape can be used. For example, MCMB may have a spherical shape, which is preferable. In addition, MCMB is relatively easy to reduce its surface area and may be preferable. Examples of natural graphite include scaly graphite and spheroidized natural graphite.

Graphite exhibits a potential as low as lithium metal when lithium ions are inserted into graphite (during the formation of a lithium-graphite interlayer compound) (0.05V or more and 0.3V or less vs. Li / Li ⁺ ). As a result, the lithium ion secondary battery can exhibit a high operating voltage. Further, graphite is preferable because it has advantages such as relatively high capacity per unit volume, relatively small volume expansion, low cost, and high safety as compared with lithium metal.

Further, as the negative electrode active material, titanium dioxide (TIM ₂ ), lithium titanium oxide (Li ₄ Ti ₅ O ₁₂ ), lithium-graphite interlayer compound (Li _x C ₆ ), niobium pentoxide (Nb ₂ O ₅ ), oxidation. Oxides such as tungsten (WO ₂ ) and molybdenum oxide (MoO ₂ ) can be used.

Further, as the negative electrode active material, Li _{3 -x} M _x N (M = Co, Ni, Cu) having a Li 3N type structure, which is a double nitride of lithium and a transition metal, can be used. For example, Li _2.6 Co _0.4 N ₃ shows a large charge / discharge capacity (900 mAh / g, 1890 mAh / cm ³ ) and is preferable.

When a double nitride of lithium and a transition metal is used, lithium ions are contained in the negative electrode active material, so that it can be combined with materials such as V ₂ O ₅ and Cr ₃ O ₈ which do not contain lithium ions as the positive electrode active material, which is preferable. .. Even when a material containing lithium ions is used as the positive electrode active material, a double nitride of lithium and a transition metal can be used as the negative electrode active material by desorbing the lithium ions contained in the positive electrode active material in advance.

Further, a material that causes a conversion reaction can also be used as a negative electrode active material. For example, a transition metal oxide that does not form an alloy with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), may be used as the negative electrode active material. Further, as the material in which the conversion reaction occurs, oxides such as Fe ₂ O ₃ , CuO, Cu ₂ O, RuO ₂ , Cr ₂ O ₃ and sulfides such as CoS _0.89 , NiS and CuS, Zn ₃ N ₂ , Cu ₃ N, Ge ₃ N ₄ , etc., phosphodies such as NiP ₂ , FeP ₂ , CoP ₃ , etc., and fluorides such as FeF ₃ , BiF ₃ etc. also occur.

[Conductive aid]
As the conductive auxiliary agent, a carbon material, a metal material, a conductive ceramic material, or the like can be used. Further, a fibrous material may be used as the conductive auxiliary agent. The content of the conductive auxiliary agent with respect to the total amount of the active material layer is preferably 1 wt% or more and 10 wt% or less, and more preferably 1 wt% or more and 5 wt% or less.

The conductive auxiliary agent can form a network of electrical conduction in the active material layer. In addition, the conductive auxiliary agent can maintain the path of electrical conduction between active materials. By adding a conductive additive to the active material layer, an active material layer having high electrical conductivity can be realized.

As the conductive auxiliary agent, for example, natural graphite, artificial graphite such as mesocarbon microbeads, carbon fiber and the like can be used. As the carbon fiber, for example, carbon fiber such as mesophase pitch type carbon fiber and isotropic pitch type carbon fiber can be used. Further, as the carbon fiber, carbon nanofiber, carbon nanotube, or the like can be used. The carbon nanotubes can be produced, for example, by a vapor phase growth method. Further, as the conductive auxiliary agent, for example, a carbon material such as carbon black (acetylene black (AB) or the like), graphite (graphite) particles, graphene, fullerene or the like can be used. Further, for example, metal powders such as copper, nickel, aluminum, silver and gold, metal fibers, conductive ceramic materials and the like can be used.

Further, a graphene compound having high conductivity may be used as the conductive auxiliary agent. Further, the protective layer 53, the protective layer 56, or the like may function as a conductive auxiliary agent.

[Binder]
As the binder, for example, it is preferable to use a rubber material such as styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, and ethylene-propylene-diene copolymer. Further, fluororubber can be used as the binder.

Further, as the binder, for example, it is preferable to use a water-soluble polymer. As the water-soluble polymer, for example, a polysaccharide or the like can be used. As the polysaccharide, cellulose derivatives such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose and regenerated cellulose, starch and the like can be used. Further, it is more preferable to use these water-soluble polymers in combination with the above-mentioned rubber material.

Alternatively, the binder includes polystyrene, methyl polyacrylate, methyl polymethacrylate (polymethylmethacrylate (PMMA)), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, and polychloride. Materials such as vinyl, polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), ethylenepropylene diene polymer, polyvinyl acetate, and nitrocellulose can be used. preferable.

A plurality of the above binders may be used in combination.

For example, a material having a particularly excellent viscosity adjusting effect may be used in combination with another material. For example, a rubber material or the like has excellent adhesive strength and elastic strength, but it may be difficult to adjust the viscosity when mixed with a solvent. In such a case, for example, it is preferable to mix with a material having a particularly excellent viscosity adjusting effect. As a material having a particularly excellent viscosity adjusting effect, for example, a water-soluble polymer may be used. Further, as the water-soluble polymer having a particularly excellent viscosity adjusting effect, the above-mentioned polysaccharides such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose and diacetyl cellulose, cellulose derivatives such as regenerated cellulose, and starch are used. be able to.

In addition, the cellulose derivative such as carboxymethyl cellulose has higher solubility by using, for example, a salt such as a sodium salt or an ammonium salt of carboxymethyl cellulose, and easily exerts an effect as a viscosity adjusting agent. By increasing the solubility, it is possible to improve the dispersibility with the active material and other components when preparing the slurry of the electrode. In the present specification, the cellulose and the cellulose derivative used as the binder of the electrode include salts thereof.

The water-soluble polymer stabilizes its viscosity by being dissolved in water, and can stably disperse an active substance and other materials to be combined as a binder, such as styrene-butadiene rubber, in an aqueous solution. Further, since it has a functional group, it is expected that it can be easily stably adsorbed on the surface of the active material. In addition, many cellulose derivatives such as carboxymethyl cellulose have functional groups such as hydroxyl groups and carboxyl groups, and since they have functional groups, the polymers interact with each other and exist widely covering the surface of the active material. There is expected.

When the binder that covers the surface of the active material or is in contact with the surface forms a film, it is expected to play a role as a passivation film and suppress the decomposition of the electrolytic solution. Here, the immobile membrane is a membrane having no electrical conductivity or a membrane having extremely low electrical conductivity. For example, when a dynamic membrane is formed on the surface of an active material, in the battery reaction potential, Decomposition of the electrolytic solution can be suppressed. Further, it is more desirable that the passivation membrane suppresses the conductivity of electricity and can conduct lithium ions.

The above is the description of the material contained in the electrode 50.

This embodiment can be used in combination with other embodiments as appropriate.

(Embodiment 2)
In this embodiment, a power storage device that can use the electrode of one aspect of the present invention described in the previous embodiment will be described. The electrode of one aspect of the present invention can be used as either or both of the positive electrode and the negative electrode of the power storage device described below.

As an example of the power storage device of one aspect of the present invention, a secondary battery using an electrochemical reaction such as a lithium ion battery, an electrochemical capacitor such as an electric double layer capacitor and a redox capacitor, an air battery, a fuel cell and the like can be mentioned.

<Thin storage battery>
FIG. 5 shows a thin storage battery as an example of a power storage device. FIG. 5 shows an example of a thin storage battery. If the thin storage battery has a flexible configuration and is mounted on an electronic device having at least a part of the flexible portion, the storage battery can also be bent according to the deformation of the electronic device.

FIG. 5 shows an external view of the storage battery 500, which is a thin storage battery. 6 (A) and 6 (B) show the A1-A2 cross section and the B1-B2 cross section shown by the alternate long and short dash line in FIG. The storage battery 500 includes a positive electrode 503 having a positive electrode current collector 501 and a positive electrode active material layer 502, a negative electrode 506 having a negative electrode current collector 504 and a negative electrode active material layer 505, a separator 507, an electrolytic solution 508, and an exterior body 509. And have. A separator 507 is installed between the positive electrode 503 and the negative electrode 506 provided in the exterior body 509. Further, the inside of the exterior body 509 is filled with the electrolytic solution 508.

The solvent of the electrolytic solution 508 is preferably an aprotic organic solvent, for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl. Carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), methyl formate, methyl acetate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether , Methyl diglyme, acetonitrile, benzonitrile, tetrahydrofuran, sulfolan, sulton and the like, or two or more of these can be used in any combination and ratio.

Further, by using one or more flame-retardant and flame-retardant ionic liquids (normal temperature molten salt) as the solvent of the electrolytic solution, the internal temperature rises due to an internal short circuit of the power storage device, overcharging, or the like. However, it is possible to prevent the power storage device from exploding or catching fire. Ionic liquids consist of cations and anions, including organic cations and anions. Examples of the organic cation used in the electrolytic solution include aliphatic onium cations such as quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, and aromatic cations such as imidazolium cations and pyridinium cations. Further, as anions used in the electrolytic solution, monovalent amide anions, monovalent methide anions, fluorosulfonic acid anions, perfluoroalkyl sulfonic acid anions, tetrafluoroborate anions, perfluoroalkyl borate anions, and hexafluorophosphate anions. , Or perfluoroalkyl phosphate anion and the like.

When lithium ion is used as the carrier as the electrolyte to be dissolved in the above solvent, for example, LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiAlCl ₄ , LiSCN, LiBr, LiI, Li ₂ SO ₄ , Li ₂ B. ₁₀ Cl ₁₀ , Li ₂ B ₁₂ Cl ₁₂ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , LiN (CF ₃ SO ₂ ) _2. Lithium salts such as LiN (C ₄ F ₉ SO ₂ ) (CF ₃ SO ₂ ), LiN (C ₂ F ₅ SO ₂ ) ₂ , etc., or two or more of these in any combination and ratio. Can be used.

As the electrolytic solution used in the power storage device, it is preferable to use a highly purified electrolytic solution having a small content of granular dust and elements other than the constituent elements of the electrolytic solution (hereinafter, also simply referred to as “impurities”). Specifically, the weight ratio of impurities to the electrolytic solution is preferably 1% or less, preferably 0.1% or less, and more preferably 0.01% or less.

Further, additives such as vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), and lithium bis (oxalate) borate (LiBOB) may be added to the electrolytic solution. The concentration of the material to be added may be, for example, 0.1 weight% or more and 5 weight% or less with respect to the entire solvent.

Further, a polymer gel electrolyte obtained by swelling the polymer with an electrolytic solution may be used. By using the polymer gel electrolyte, the safety against liquid leakage and the like is enhanced. In addition, the secondary battery can be made thinner and lighter.

As the gelled polymer, silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide gel, polypropylene oxide gel, fluoropolymer gel and the like can be used. As the polymer, for example, a polymer having a polyalkylene oxide structure such as polyethylene oxide (PEO), PVdF, polyacrylonitrile and the like, and a copolymer containing them can be used. For example, PVdF-HFP, which is a copolymer of PVdF and hexafluoropropylene (HFP), can be used. Further, the polymer to be formed may have a porous shape.

Further, instead of the electrolytic solution, a gel-like electrolyte using a liquid crystal material having carrier ion conductivity can also be used. As the liquid crystal material having carrier ion conductivity, for example, a material having an ethylene oxide chain or a compound having a propylene oxide chain and a metal salt containing a metal ion such as a carrier ion and having a function of self-assembling is used. Can be done. Further, the liquid crystal material having carrier ion conductivity is preferably a liquid crystal exhibiting a smectic phase. As the compound having an ethylene oxide chain or a propylene oxide chain, a complex consisting of a cation and an anion may be used. As the metal salt containing a metal ion such as a carrier ion, for example, when lithium ion is used as a carrier, LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ or Li (CF ₃ SO ₂ ) ₂ N or the like can be used.

Further, instead of the electrolytic solution, a solid electrolyte having an inorganic material such as a sulfide type or an oxide type, or a solid electrolyte having a polymer material such as PEO type can be used.

When a gel-like electrolyte using a liquid crystal material having carrier ion conductivity or a solid electrolyte is used, it is not necessary to install a separator or a spacer. In addition, there is no risk of liquid leakage and safety is dramatically improved. That is, the possibility of explosion, ignition, smoke generation, etc. of the power storage device can be significantly reduced.

As the separator 507, for example, one made of paper, non-woven fabric, glass fiber, ceramics, nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyester, acrylic, polyolefin, synthetic fiber using polyurethane or the like is used. be able to.

It is preferable that the separator 507 is processed into a bag shape and arranged so as to wrap either the positive electrode 503 or the negative electrode 506. For example, as shown in FIG. 7 (A), the separator 507 is folded in half so as to sandwich the positive electrode 503, and the positive electrode 503 is sealed by the sealing portion 514 outside the region overlapping with the positive electrode 503. It can be reliably carried inside. Then, as shown in FIG. 7B, the positive electrode 503 and the negative electrode 506 wrapped in the separator 507 may be alternately laminated and arranged in the exterior body 509 to form the storage battery 500.

Next, aging after manufacturing the storage battery will be described. It is preferable to perform aging after manufacturing the storage battery. An example of the aging condition will be described below. First, charging is performed at a rate of 0.001C or more and 0.2C or less. The temperature may be, for example, room temperature or higher and 50 ° C. or lower. Here, when the reaction potentials of the positive electrode and the negative electrode exceed the range of the potential window of the electrolytic solution 508, the electrolytic solution may be decomposed by charging and discharging the storage battery. When gas is generated by the decomposition of the electrolytic solution, when the gas accumulates in the cell, a region where the electrolytic solution cannot come into contact with the electrode surface is generated. That is, it corresponds to a decrease in the effective reaction area of the electrode and an increase in the effective resistance.

Further, when the resistance becomes excessively high, the negative electrode potential is lowered, so that lithium is inserted into graphite and at the same time lithium is deposited on the graphite surface. This lithium precipitation may lead to a decrease in capacity. For example, if a film or the like grows on the surface after lithium is deposited, the lithium deposited on the surface cannot be re-eluted, and the amount of lithium that does not contribute to the capacity increases. Further, even when the precipitated lithium physically collapses and loses the continuity with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to remove the gas before the potential of the negative electrode reaches the lithium potential due to the increase in the charging voltage.

Further, after degassing, the product may be held in a charged state at a temperature higher than room temperature, preferably 30 ° C. or higher and 60 ° C. or lower, more preferably 35 ° C. or higher and 50 ° C. or lower, for example, 1 hour or more and 100 hours or less. good. During the initial charging, the electrolytic solution decomposed on the surface forms a film on the surface of graphite. Therefore, for example, by holding the film at a temperature higher than room temperature after degassing, the formed film may be densified.

FIG. 8 shows an example of welding a current collector to a lead electrode. As shown in FIG. 8A, the positive electrode 503 wrapped in the separator 507 and the negative electrode 506 are alternately stacked. Next, the positive electrode current collector 501 is welded to the positive electrode lead electrode 510, and the negative electrode current collector 504 is welded to the negative electrode lead electrode 511. FIG. 8B shows an example of welding the positive electrode current collector 501 to the positive electrode lead electrode 510. The positive electrode current collector 501 is welded to the positive electrode lead electrode 510 in the welding region 512 by using ultrasonic welding or the like. Further, since the positive electrode current collector 501 has the curved portion 513 shown in FIG. 8B, it is possible to relieve the stress generated by applying an external force after the storage battery 500 is manufactured, and the reliability of the storage battery 500 can be reduced. Can be enhanced.

In the storage battery 500 shown in FIGS. 5 and 6, the positive electrode lead electrode 510 is ultrasonically bonded to the positive electrode collector 501 of the positive electrode 503, and the negative electrode lead electrode 511 is ultrasonically bonded to the negative electrode current collector 504 of the negative electrode 506. Further, the positive electrode current collector 501 and the negative electrode current collector 504 can also serve as terminals for obtaining electrical contact with the outside. In that case, a part of the positive electrode current collector 501 and the negative electrode current collector 504 may be arranged so as to be exposed to the outside from the exterior body 509 without using the lead electrode.

Further, although the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are arranged on the same side in FIG. 5, as shown in FIG. 9, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 may be arranged on different sides. As described above, in the storage battery of one aspect of the present invention, the lead electrodes can be freely arranged, so that the degree of freedom in design is high. Therefore, the degree of freedom in designing a product using the storage battery of one aspect of the present invention can be increased. In addition, the productivity of a product using the storage battery of one aspect of the present invention can be increased.

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

Further, in FIG. 6, as an example, the total number of positive electrodes and negative electrodes is 6, but of course, the number of electrodes is not limited to 6, and may be large or small. When the number of electrodes is large, a storage battery having a larger capacity can be obtained. Further, when the number of electrodes is small, the storage battery can be made thinner and has excellent flexibility.

In the above configuration, the exterior body 509 of the secondary battery can be deformed so that the minimum radius of curvature is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less. The film that is the exterior body of the secondary battery is composed of one or two sheets, and in the case of a secondary battery having a laminated structure, the cross-sectional structure of the curved battery is two curves of the film that is the exterior body. The structure is sandwiched between.

The radius of curvature of the surface will be described with reference to FIG. In FIG. 10A, in a plane 1701 obtained by cutting a curved surface 1700, a part of the curve 1702 included in the curved surface 1700 is approximated to an arc of a circle, the radius of the circle is set to the radius of curvature 1703, and the center of the circle is the curvature. The center is 1704. FIG. 10B shows a top view of the curved surface 1700. FIG. 10C shows a cross-sectional view of a curved surface 1700 cut along a plane 1701. When cutting a curved surface with a plane, the radius of curvature of the curve appearing in the cross section differs depending on the angle of the plane with respect to the curved surface and the cutting position. do.

When a secondary battery sandwiching 1805 such as an electrode and an electrolytic solution is curved using two films as an exterior body, the radius of curvature 1802 of the film 1801 on the side closer to the center of curvature 1800 of the secondary battery is from the center of curvature 1800. It is smaller than the radius of curvature 1804 of the film 1803 on the far side (FIG. 11 (A)). When the secondary battery is curved to have an arcuate cross section, compressive stress is applied to the surface of the film near the center of curvature 1800, and tensile stress is applied to the surface of the film far from the center of curvature 1800 (FIG. 11B). By forming a pattern formed by concave portions or convex portions on the surface of the exterior body, even if compressive stress or tensile stress is applied in this way, the influence of strain can be suppressed within an allowable range. Therefore, the secondary battery can be deformed so that the minimum radius of curvature of the exterior body near the center of curvature is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less.

The cross-sectional shape of the secondary battery is not limited to a simple arc shape, and can be a shape having a partial arc shape, for example, the shape shown in FIG. 11 (C) or the wavy shape (FIG. 11 (D)). ), S-shaped, etc. When the curved surface of the secondary battery has a shape having a plurality of centers of curvature, the curved surface having the smallest radius of curvature among the radii of curvature at each of the plurality of centers of curvature is closer to the center of curvature of the two exterior bodies. The outer body can be deformed so that the minimum radius of curvature is, for example, 3 mm or more and 30 mm or less, more preferably 3 mm or more and 10 mm or less.

Next, various examples of laminating the positive electrode, the negative electrode, and the separator will be shown.

FIG. 14A shows an example in which the positive electrode 111 and the negative electrode 115 are laminated in 6 layers each. A positive electrode active material layer 122 is provided on one side of the positive electrode current collector 121 of the positive electrode 111. Further, the negative electrode active material layer 126 is provided on one side of the negative electrode current collector 125 of the negative electrode 115.

Further, in the configuration shown in FIG. 14A, the positive electrode 111 is in contact with each other so that the surfaces of the positive electrode 111 that do not have the positive electrode active material layer 122 are in contact with each other and the surfaces of the negative electrode 115 that do not have the negative electrode active material layer 126 are in contact with each other. And the negative electrode 115 are laminated. By adopting such a stacking order, it is possible to create contact surfaces between the metals, that is, the surfaces of the positive electrode 111 that do not have the positive electrode active material layer 122 and the surfaces of the negative electrode 115 that do not have the negative electrode active material layer 126. can. The contact surface between the metals can have a smaller coefficient of friction than the contact surface between the active material and the separator.

Therefore, when the secondary battery 10 is curved, the surfaces of the positive electrode 111 that do not have the positive electrode active material layer 122 and the surfaces of the negative electrode 115 that do not have the negative electrode active material layer 126 slip, so that the inner and outer diameters of the curve are curved. The stress caused by the difference in diameter can be released. Here, the curved inner diameter refers to, for example, the radius of curvature of a surface located inside the curved portion in the exterior body 509 of the storage battery 500 when the storage battery 500 is curved. Therefore, deterioration of the storage battery 500 can be suppressed. Further, the storage battery 500 can be highly reliable.

Further, FIG. 14B shows an example of stacking the positive electrode 111 and the negative electrode 115, which are different from those in FIG. 14A. The configuration shown in FIG. 14B is different from the configuration shown in FIG. 14A in that the positive electrode active material layers 122 are provided on both sides of the positive electrode current collector 121. By providing the positive electrode active material layers 122 on both sides of the positive electrode current collector 121 as shown in FIG. 14B, the capacity per unit volume of the storage battery 500 can be increased.

Further, FIG. 14C shows an example of stacking the positive electrode 111 and the negative electrode 115, which are different from those in FIG. 14B. The configuration shown in FIG. 11C is different from the configuration shown in FIG. 11B in that the negative electrode active material layers 126 are provided on both sides of the negative electrode current collector 125. By providing the negative electrode active material layers 126 on both sides of the negative electrode current collector 125 as shown in FIG. 11C, the capacity per unit volume of the storage battery 500 can be further increased.

Further, in the configurations shown in FIGS. 14 and 14, the separator 123 is configured to wrap the positive electrode 111 in a bag shape, but the present invention is not limited to this. Here, FIG. 15A shows an example having a separator 123 having a configuration different from that of FIG. 14A. The configuration shown in FIG. 15A differs from the configuration shown in FIG. 14A in that a sheet-shaped separator 123 is provided between the positive electrode active material layer 122 and the negative electrode active material layer 126 one by one. .. In the configuration shown in FIG. 15A, the positive electrode 111 and the negative electrode 115 are laminated in 6 layers each, and the separator 123 is provided in 6 layers.

Further, FIG. 15B shows an example in which a separator 123 different from that in FIG. 15A is provided. In the configuration shown in FIG. 15B, one separator 123 is folded back so as to be sandwiched between the positive electrode active material layer 122 and the negative electrode active material layer 126, and is shown in FIG. 15A. Different from the configuration. Further, the configuration of FIG. 15B can also be said to be a configuration in which the separator 123 of each layer of the configuration shown in FIG. 15A is extended to connect the layers. In the configuration shown in FIG. 15B, it is preferable that the positive electrode 111 and the negative electrode 115 are laminated in 6 layers each, and the separator 123 is folded back at least 5 times. Further, the separator 123 is not only provided so as to be sandwiched between the positive electrode active material layer 122 and the negative electrode active material layer 126, but may be extended to bind the plurality of positive electrode 111 and the negative electrode 115 together. ..

Further, as shown in FIG. 16, the positive electrode, the negative electrode and the separator may be laminated. 16 (A) is a sectional view of the first electrode assembly 130, and FIG. 16 (B) is a sectional view of the second electrode assembly 131. 16 (C) is a cross-sectional view taken along the one-dot broken line A1-A2 of FIG. 1 (A). In FIG. 16C, the first electrode assembly 130, the electrode assembly 131, and the separator 123 are excerpted and shown in order to clarify the figure.

As shown in FIG. 16C, the storage battery 500 has a plurality of first electrode assemblies 130 and a plurality of electrode assemblies 131.

As shown in FIG. 16A, in the first electrode assembly 130, the positive electrode 111a, the separator 123, and the negative electrode current collector 125 having the positive electrode active material layers 122 on both sides of the positive electrode current collector 121 have negative electrode activity on both sides. The negative electrode 115a having the material layer 126, the separator 123, and the positive electrode 111a having the positive electrode active material layer 122 are laminated in this order on both surfaces of the positive electrode current collector 121. Further, as shown in FIG. 16B, in the second electrode assembly 131, the negative electrode 115a having the negative electrode active material layers 126 on both sides of the negative electrode current collector 125, the separator 123, and the positive electrode on both sides of the positive electrode current collector 121 are positive electrodes. The positive electrode 111a having the negative electrode active material layer 122, the separator 123, and the negative electrode 115a having the negative electrode active material layer 126 are laminated in this order on both surfaces of the positive electrode 111a having the active material layer 122, the separator 123, and the negative electrode current collector 125.

Further, as shown in FIG. 16C, the plurality of first electrode assemblies 130 and the plurality of electrode assemblies 131 are covered with the wound separator 123.

[Coin-type storage battery]
Next, as an example of the power storage device, an example of a coin-type storage battery will be described with reference to FIG. FIG. 12A is an external view of a coin-type (single-layer flat type) storage battery, and FIG. 12B is a sectional view thereof.

In the coin-type storage battery 300, 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 are insulated and sealed with a gasket 303 that is made of polypropylene or the like. The positive electrode 304 is formed by a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector 305.

Further, the negative electrode 307 is formed by a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact with the negative electrode current collector 308.

For the positive electrode 304, the description of the positive electrode 503 may be referred to. For the positive electrode active material layer 306, the positive electrode active material layer 502 may be referred to. For the negative electrode 307, the negative electrode 506 may be referred to. For the negative electrode active material layer 309, the description of the negative electrode active material layer 505 may be referred to. For the separator 310, the description of the separator 507 may be referred to. As the electrolytic solution, the description of the electrolytic solution 508 may be referred to.

The positive electrode 304 and the negative electrode 307 used in the coin-type storage battery 300 may have the active material layer formed on only one side thereof.

For the positive electrode can 301 and the negative electrode can 302, metals such as nickel, aluminum, and titanium having corrosion resistance to the electrolytic solution, or alloys thereof or alloys of these with other metals (for example, stainless steel) may be used. can. Further, in order to prevent corrosion due to the electrolytic solution, it is preferable to coat with nickel, aluminum or the like. 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.

The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated into the electrolyte, and as shown in FIG. 12B, the positive electrode 304, the separator 310, the negative electrode 307, and the negative electrode can 302 are laminated in this order with the positive electrode can 301 facing down. , The positive electrode can 301 and the negative electrode can 302 are crimped via the gasket 303 to manufacture a coin-shaped storage battery 300.

[Cylindrical storage battery]
Next, as an example of the power storage device, a cylindrical storage battery will be shown. A cylindrical storage battery will be described with reference to FIG. As shown in FIG. 13A, the cylindrical storage battery 600 has a positive electrode cap (battery lid) 601 on the upper surface and a battery can (exterior can) 602 on the side surface and the bottom surface. These positive electrode caps and the battery can (exterior can) 602 are insulated by a gasket (insulating packing) 610.

FIG. 13B is a diagram schematically showing a cross section of a cylindrical storage battery. Inside the hollow cylindrical battery can 602, a battery element in which a band-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched between them is provided. Although not shown, the battery element is wound around the center pin. One end of the battery can 602 is closed and the other end is open. For the battery can 602, a metal such as nickel, aluminum, or titanium that is corrosion resistant to an electrolytic solution, or an alloy thereof or an alloy of these and another metal (for example, stainless steel or the like) can be used. .. Further, in order to prevent corrosion due to the electrolytic solution, it is preferable to coat with nickel, aluminum or the like. Inside the battery can 602, the battery element in which the positive electrode, the negative electrode, and the separator are wound is sandwiched between a pair of insulating plates 608 and 609 facing each other. Further, a non-aqueous electrolytic solution (not shown) is injected into the inside of the battery can 602 provided with the battery element. As the non-aqueous electrolyte solution, the same one as that of a coin-type storage battery can be used.

For the positive electrode 604, the positive electrode 503 may be referred to. Further, for the negative electrode 606, the negative electrode 506 may be referred to. Further, for the positive electrode 604 and the negative electrode 606, for example, the method for manufacturing an electrode shown in the first embodiment can be referred to. Since the positive electrode and the negative electrode used in the cylindrical storage battery are wound, it is preferable to form active substances on both sides of the current collector. A positive electrode terminal (positive electrode current collecting lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative electrode current collecting lead) 607 is connected to the negative electrode 606. A metal material such as aluminum can be used for both the positive electrode terminal 603 and the negative electrode terminal 607. 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 increase in the internal pressure of the battery exceeds a predetermined threshold value. Further, the PTC element 611 is a heat-sensitive resistance element whose resistance increases when the temperature rises, and the amount of current is limited by the increase in resistance to prevent abnormal heat generation. Barium titanate (BaTIO ₃ ) -based semiconductor ceramics or the like can be used as the PTC element.

When the electrode is wound like a cylindrical storage battery as shown in FIG. 13, a large stress acts on the electrode at the time of winding. Further, when the winding body of the electrode is housed in the housing, stress toward the outside of the winding shaft always acts on the electrode. Even if a large stress acts on the electrodes in this way, it is possible to prevent the active material from cleaving.

In the present embodiment, the coin-type, cylindrical, and thin storage batteries are shown as the storage batteries, but other sealed storage batteries, square storage batteries, and other storage batteries having various shapes can be used. Further, a structure in which a plurality of positive electrodes, negative electrodes, and separators are laminated, and a structure in which positive electrodes, negative electrodes, and separators are wound may be used. For example, examples of other storage batteries are shown in FIGS. 17 to 21.

[Example of thin storage battery configuration]
17 and 18 show a configuration example of a thin storage battery. The winding body 993 shown in FIG. 17A has a negative electrode 994, a positive electrode 995, and a separator 996.

The wound body 993 is formed by laminating a negative electrode 994 and a positive electrode 995 on top of each other with a separator 996 interposed therebetween, and winding the laminated sheet. A square secondary battery is manufactured by covering the winding body 993 with a square sealing container or the like.

The number of layers of the negative electrode 994, the positive electrode 995, and the separator 996 may be appropriately designed according to the required capacity and the element volume. The negative electrode 994 is connected to the negative electrode current collector (not shown) via one of the lead electrode 997 and the lead electrode 998, and the positive electrode 995 is connected to the positive electrode current collector (not shown) via the other of the lead electrode 997 and the lead electrode 998. Is connected to.

The storage battery 990 shown in FIGS. 17B and 17C is a wound body 993 described above in a space formed by bonding a film 981 as an exterior body and a film 982 having a recess by thermocompression bonding or the like. Is stored. The wound body 993 has a lead electrode 997 and a lead electrode 998, and is impregnated with an electrolytic solution inside the film 981 and the film 982 having a recess.

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

Further, although FIGS. 17 (B) and 17 (C) show an example in which two films are used, a space is formed by bending one film, and the above-mentioned winding body 993 is placed in the space. You may store it.

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

For example, FIG. 18 shows an example of another thin storage battery having flexibility. Since the winding body 993 of FIG. 18A is the same as that shown in FIG. 17A, detailed description thereof will be omitted.

The storage battery 990 shown in FIGS. 18B and 18C contains the above-mentioned winding body 993 inside the exterior body 991. The wound body 993 has a lead electrode 997 and a lead electrode 998, and is impregnated with an electrolytic solution inside the exterior bodies 991 and 992. For the exterior bodies 991 and 992, a metal material such as aluminum or a resin material can be used. If a resin material is used as the material of the exterior bodies 991 and 992, the exterior bodies 991 and 992 can be deformed when an external force is applied, and a flexible thin storage battery can be manufactured.

By using the electrode containing the active material according to one aspect of the present invention for a flexible thin storage battery, the active material is cleaved even if stress is applied to the electrode by repeatedly bending the thin storage battery. Can be prevented.

As described above, by using an active material in which at least a part of the cleavage plane is covered with graphene for the electrode, it is possible to suppress a decrease in the voltage of the battery and a decrease in the discharge capacity. This makes it possible to improve the cycle characteristics of the battery during charging and discharging.

[Structural example of power storage system]
Further, a structural example of the power storage system will be described with reference to FIGS. 19 to 21. Here, the power storage system refers to, for example, a device equipped with a power storage device.

19 (A) and 19 (B) are views showing an external view of the power storage system. The power storage system includes a circuit board 900 and a storage battery 913. A label 910 is affixed to the storage battery 913. Further, as shown in FIG. 19B, the power storage system has a terminal 951, a terminal 952, an antenna 914, and an antenna 915.

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

The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 914 and the antenna 915 are not limited to the coil shape, and may be, for example, a linear shape or a plate shape. Further, antennas such as a planar antenna, an open surface antenna, a traveling wave antenna, an EH antenna, a magnetic field antenna, and a dielectric antenna may be used. Alternatively, the antenna 914 or the antenna 915 may be a flat conductor. This flat plate-shaped conductor can function as one of the conductors for electric field coupling. That is, the antenna 914 or the antenna 915 may function as one of the two conductors of the capacitor. This makes it possible to exchange electric power not only with an electromagnetic field and a magnetic field but also with an electric field.

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

The power storage system has a layer 916 between the antenna 914 and the antenna 915 and the storage battery 913. The layer 916 has a function of being able to shield the electromagnetic field generated by the storage battery 913, for example. As the layer 916, for example, a magnetic material can be used.

The structure of the power storage system is not limited to the structure shown in FIG.

For example, as shown in FIGS. 20 (A-1) and 20 (A-2), antennas are provided on each of the pair of facing surfaces of the storage battery 913 shown in FIGS. 19 (A) and 19 (B). It may be provided. FIG. 20 (A-1) is an external view of the pair of surfaces viewed from one side, and FIG. 20 (A-2) is an external view of the pair of surfaces viewed from the other side. For the same parts as the power storage system shown in FIGS. 19A and 19B, the description of the power storage system shown in FIGS. 19A and 19B can be appropriately referred to.

As shown in FIG. 20 (A-1), the antenna 914 is provided on one of the pair of surfaces of the storage battery 913 with the layer 916 interposed therebetween, and as shown in FIG. 20 (A-2), the pair of surfaces of the storage battery 913. The antenna 915 is provided on the other side of the antenna 917 with the layer 917 interposed therebetween. The layer 917 has a function of being able to shield the electromagnetic field generated by the storage battery 913, for example. As the layer 917, for example, a magnetic material can be used.

With the above structure, the sizes of both the antenna 914 and the antenna 915 can be increased.

Alternatively, as shown in FIGS. 20 (B-1) and 20 (B-2), of the storage batteries 913 shown in FIGS. 19 (A) and 19 (B), each of the pair of facing surfaces is different. An antenna may be provided. FIG. 20 (B-1) is an external view of the pair of faces viewed from one side, and FIG. 20 (B-2) is an external view of the pair of faces viewed from the other side. For the same parts as the power storage system shown in FIGS. 19A and 19B, the description of the power storage system shown in FIGS. 19A and 19B can be appropriately referred to.

As shown in FIG. 20 (B-1), the antenna 914 and the antenna 915 are provided on one of the pair of surfaces of the storage battery 913 with the layer 916 interposed therebetween, and as shown in FIG. 20 (B-2), the storage battery 913 is provided. The antenna 918 is provided on the other side of the pair of surfaces with the layer 917 interposed therebetween. The antenna 918 has, for example, a function capable of performing data communication with an external device. As the antenna 918, for example, an antenna having a shape applicable to the antenna 914 and the antenna 915 can be applied. As a communication method between the power storage system and other devices via the antenna 918, a response method that can be used between the power storage system and other devices such as NFC can be applied.

Alternatively, as shown in FIG. 21 (A), the display device 920 may be provided in the storage battery 913 shown in FIGS. 19 (A) and 19 (B). The display device 920 is electrically connected to the terminal 911 via the terminal 919. It is not necessary to provide the label 910 in the portion where the display device 920 is provided. For the same parts as the power storage system shown in FIGS. 19A and 19B, the description of the power storage system shown in FIGS. 19A and 19B can be appropriately referred to.

The display device 920 may display, for example, an image showing whether or not charging is in progress, an image showing the amount of stored electricity, and the like. As the display device 920, for example, an electronic paper, a liquid crystal display device, an electroluminescence (also referred to as EL) display device, or the like can be used. For example, the power consumption of the display device 920 can be reduced by using electronic paper.

Alternatively, as shown in FIG. 21 (B), the sensor 921 may be provided in the storage battery 913 shown in FIGS. 19 (A) and 19 (B). The sensor 921 is electrically connected to the terminal 911 via the terminal 922. For the same parts as the power storage system shown in FIGS. 19A and 19B, the description of the power storage system shown in FIGS. 19A and 19B can be appropriately referred to.

The sensor 921 includes, for example, force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, voice, time, hardness, electric field, current, voltage, electric power, radiation. , Flow rate, humidity, gradient, vibration, odor or infrared can be measured. By providing the sensor 921, for example, data (temperature or the like) indicating the environment in which the power storage system is placed can be detected and stored in the memory in the circuit 912.

The electrodes according to one aspect of the present invention are used in the storage battery and the power storage system shown in the present embodiment. Therefore, the capacity of the storage battery or the power storage system can be increased. In addition, the energy density can be increased. In addition, reliability can be improved. In addition, the life can be extended.

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

(Embodiment 3)
In this embodiment, an example of mounting a flexible storage battery in an electronic device will be described as a mode in which the electrode of one aspect of the present invention can be applied.

FIG. 22 shows an example of mounting the flexible storage battery shown in the fourth embodiment on an electronic device. Electronic devices to which a power storage device with a flexible shape is applied include, for example, television devices (also referred to as televisions or television receivers), monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones. (Also referred to as a mobile phone or a mobile phone device), a portable game machine, a mobile information terminal, a sound reproduction device, a large game machine such as a pachinko machine, and the like can be mentioned.

It is also possible to incorporate a power storage device having a flexible shape along the inner or outer wall of a house or building, or along the curved surface of the interior or exterior of an automobile.

FIG. 22A shows an example of a mobile phone. The mobile phone 7400 includes an operation button 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like, in addition to the display unit 7402 incorporated in the housing 7401. The mobile phone 7400 has a power storage device 7407.

FIG. 22B shows a state in which the mobile phone 7400 is curved. When the mobile phone 7400 is deformed by an external force to bend the whole, the power storage device 7407 provided inside the mobile phone 7400 is also bent. Further, the state of the bent power storage device 7407 at that time is shown in FIG. 22 (C). The power storage device 7407 is a thin storage battery. The power storage device 7407 is fixed in a bent state. The power storage device 7407 has a lead electrode 7408 electrically connected to the current collector 7409. For example, the current collector 7409 is a copper foil, which is partially alloyed with gallium to improve the adhesion to the active material layer in contact with the current collector 7409, and the reliability of the power storage device 7407 in a bent state. Has a high configuration.

FIG. 22D shows an example of a bangle type display device. The portable display device 7100 includes a housing 7101, a display unit 7102, an operation button 7103, and a power storage device 7104. Further, FIG. 22 (E) shows the state of the power storage device 7104 bent. When the power storage device 7104 is attached to the user's arm in a bent state, the housing is deformed and the curvature of a part or the whole of the power storage device 7104 changes. The radius of curvature is the value of the radius of the circle corresponding to the degree of bending at any point on the curve, and the inverse of the radius of curvature is called the curvature. Specifically, a part or all of the main surface of the housing or the power storage device 7104 changes within the range of the radius of curvature of 40 mm or more and 150 mm or less. High reliability can be maintained as long as the radius of curvature on the main surface of the power storage device 7104 is in the range of 40 mm or more and 150 mm or less.

FIG. 22F shows an example of a wristwatch-type personal digital assistant. The mobile information terminal 7200 includes a housing 7201, a display unit 7202, a band 7203, a buckle 7204, an operation button 7205, an input / output terminal 7206, and the like.

The personal digital assistant 7200 can execute various applications such as mobile phone, e-mail, text viewing and creation, music playback, Internet communication, and computer games.

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

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

Further, the mobile information terminal 7200 can execute short-range wireless communication standardized for communication. For example, by communicating with a headset capable of wireless communication, it is possible to make a hands-free call.

Further, the mobile information terminal 7200 is provided with an input / output terminal 7206, and data can be directly exchanged with another information terminal via a connector. It is also possible to charge via the input / output terminal 7206. The charging operation may be performed by wireless power supply without going through the input / output terminal 7206.

The display unit 7202 of the portable information terminal 7200 has a power storage device including the electrodes of one aspect of the present invention. For example, the power storage device 7104 shown in FIG. 22E can be incorporated in a curved state inside the housing 7201 or in a bendable state inside the band 7203.

It is preferable that the portable information terminal 7200 has a sensor. As the sensor, for example, a human body sensor such as a fingerprint sensor, a pulse sensor, a body temperature sensor, a touch sensor, a pressure sensor, an acceleration sensor, or the like is preferably mounted.

FIG. 22 (G) shows an example of an armband-shaped display device. The display device 7300 has a display unit 7304 and has a power storage device according to an aspect of the present invention. Further, the display device 7300 can be provided with a touch sensor in the display unit 7304, and can also function as a portable information terminal.

The display surface of the display unit 7304 is curved, and display can be performed along the curved display surface. Further, the display device 7300 can change the display status by communication standard short-range wireless communication or the like.

Further, the display device 7300 is provided with an input / output terminal, and can directly exchange data with another information terminal via a connector. It can also be charged via the input / output terminals. The charging operation may be performed by wireless power supply without going through the input / output terminals.

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

(Embodiment 4)
In this embodiment, an example of an electronic device on which a power storage device can be mounted is shown.

23 (A) and 23 (B) show an example of a tablet-type terminal that can be folded in half. The tablet-type terminal 9600 shown in FIGS. 23A and 23B has a housing 9630a, a housing 9630b, a movable portion 9640 connecting the housing 9630a and the housing 9630b, a display unit 9631a, and a display unit 9631b. It has a display unit 9631, a display mode changeover switch 9626, a power supply switch 9627, a power saving mode changeover switch 9625, a fastener 9629, and an operation switch 9628. FIG. 23 (A) shows a state in which the tablet-type terminal 9600 is open, and FIG. 23 (B) shows a state in which the tablet-type terminal 9600 is closed.

Further, the tablet-type terminal 9600 has a storage body 9635 inside the housing 9630a and the housing 9630b. The power storage body 9635 passes through the movable portion 9640 and is provided over the housing 9630a and the housing 9630b.

A part of the display unit 9631a can be a touch panel area 9632a, and data can be input by touching the displayed operation key 9638. The display unit 9631a shows, for example, a configuration in which half of the area has a display-only function and the other half of the area has a touch panel function, but the configuration is not limited to this. The entire area of the display unit 9631a may have a touch panel function. For example, the entire surface of the display unit 9631a can be displayed as a keyboard button to form a touch panel, and the display unit 9631b can be used as a display screen.

Further, in the display unit 9631b as well, a part of the display unit 9631b can be a touch panel area 9632b, similarly to the display unit 9631a. Further, the keyboard button can be displayed on the display unit 9631b by touching the position where the keyboard display switching button 9639 on the touch panel is displayed with a finger or a stylus.

Further, touch input can be simultaneously performed on the touch panel area 9632a and the touch panel area 9632b.

Further, the display mode changeover switch 9626 can switch the display direction such as vertical display or horizontal display, and can select switching between black-and-white display and color display. The power saving mode changeover switch 9625 can optimize the brightness of the display according to the amount of external light during use detected by the optical sensor built in the tablet terminal 9600. The tablet terminal may incorporate not only an optical sensor but also another detection device such as a sensor for detecting tilt such as a gyro and an acceleration sensor.

Further, FIG. 23A shows an example in which the display areas of the display unit 9631b and the display unit 9631a are the same, but the display area is not particularly limited, and one size and the other size may be different, and the display quality is also good. It may be different. For example, one may be a display panel capable of displaying a higher definition than the other.

FIG. 23B is a closed state, and the tablet-type terminal has a charge / discharge control circuit 9634 including a housing 9630, a solar cell 9633, and a DCDC converter 9636. Further, as the electricity storage body 9635, the electricity storage body according to one aspect of the present invention is used.

Since the tablet-type terminal 9600 can be folded in two, it can be folded so that the housing 9630a and the housing 9630b overlap each other when not in use. By folding, the display unit 9631a and the display unit 9631b can be protected, so that the durability of the tablet-type terminal 9600 can be enhanced. Further, the storage body 9635 using the storage body according to one aspect of the present invention has flexibility, and the charge / discharge capacity does not easily decrease even if bending and stretching are repeated. Therefore, it is possible to provide a highly reliable tablet terminal.

In addition to this, the tablet-type terminals shown in FIGS. 23 (A) and 23 (B) have a function of displaying various information (still images, moving images, text images, etc.), a calendar, a date, a time, and the like. It can have a function of displaying on a display unit, a touch input function of performing a touch input operation or editing information displayed on the display unit, a function of controlling processing by various software (programs), and the like.

The solar cell 9633 mounted on the surface of the tablet-type terminal can supply electric power to the touch panel, the display unit, the video signal processing unit, or the like. The solar cell 9633 can be provided on one side or both sides of the housing 9630, and can be configured to efficiently charge the power storage body 9635. As the storage body 9635, if a lithium ion battery is used, there is an advantage that the size can be reduced.

Further, the configuration and operation of the charge / discharge control circuit 9634 shown in FIG. 23 (B) will be described by showing a block diagram in FIG. 23 (C). FIG. 23C shows the solar cell 9633, the storage body 9635, the DCDC converter 9636, the converter 9637, the switches SW1 to SW3, and the display unit 9631, and shows the storage body 9635, the DCDC converter 9636, the converter 9637, the switch SW1 to SW3 is a portion corresponding to the charge / discharge control circuit 9634 shown in FIG. 23 (B).

First, an example of operation when power is generated by the solar cell 9633 by external light will be described. The electric power generated by the solar cell is stepped up or down by the DCDC converter 9636 so as to be a voltage for charging the storage body 9635. Then, when the power from the solar cell 9633 is used for the operation of the display unit 9631, the switch SW1 is turned on, and the converter 9637 boosts or lowers the voltage required for the display unit 9631. Further, when the display is not performed on the display unit 9631, the SW1 may be turned off and the SW2 may be turned on to charge the storage body 9635.

The solar cell 9633 is shown as an example of the power generation means, but is not particularly limited, and the storage body 9635 is charged by another power generation means such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). May be. For example, a non-contact power transmission module that wirelessly (non-contactly) transmits and receives power for charging may be used, or a configuration may be performed in combination with other charging means.

FIG. 24 shows an example of another electronic device. In FIG. 24, the display device 8000 is an example of an electronic device using the power storage device 8004 according to one aspect of the present invention. Specifically, the display device 8000 corresponds to a display device for receiving TV broadcasts, and includes a housing 8001, a display unit 8002, a speaker unit 8003, a power storage device 8004, and the like. The power storage device 8004 according to one aspect of the present invention is provided inside the housing 8001. The display device 8000 can be supplied with electric power from a commercial power source, or can use the electric power stored in the power storage device 8004. Therefore, even when the power cannot be supplied from the commercial power supply due to a power failure or the like, the display device 8000 can be used by using the power storage device 8004 according to one aspect of the present invention as an uninterruptible power supply.

The display unit 8002 includes a liquid crystal display device, a light emitting device having a light emitting element such as an organic EL element in each pixel, an electrophoresis display device, a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), and a FED (Field Emission Display). ), Etc., a semiconductor display device can be used.

The display device includes all information display devices such as those for receiving TV broadcasts, those for personal computers, and those for displaying advertisements.

In FIG. 24, the stationary lighting device 8100 is an example of an electronic device using the power storage device 8103 according to one aspect of the present invention. Specifically, the lighting device 8100 includes a housing 8101, a light source 8102, a power storage device 8103, and the like. FIG. 24 illustrates a case where the power storage device 8103 is provided inside the ceiling 8104 in which the housing 8101 and the light source 8102 are installed, but the power storage device 8103 is provided inside the housing 8101. May be. The lighting device 8100 can be supplied with electric power from a commercial power source, or can use the electric power stored in the power storage device 8103. Therefore, even when the power supply cannot be received from the commercial power source due to a power failure or the like, the lighting device 8100 can be used by using the power storage device 8103 according to one aspect of the present invention as an uninterruptible power supply.

Although FIG. 24 illustrates the stationary lighting device 8100 provided on the ceiling 8104, the power storage device according to one aspect of the present invention is provided on a side wall 8105, a floor 8106, a window 8107, etc. other than the ceiling 8104. It can be used for a stationary lighting device provided, or it can be used for a tabletop lighting device or the like.

Further, as the light source 8102, an artificial light source that artificially obtains light by using electric power can be used. Specifically, an incandescent lamp, a discharge lamp such as a fluorescent lamp, and a light emitting element such as an LED or an organic EL element can be mentioned as an example of the artificial light source.

In FIG. 24, the air conditioner having the indoor unit 8200 and the outdoor unit 8204 is an example of an electronic device using the power storage device 8203 according to one aspect of the present invention. Specifically, the indoor unit 8200 has a housing 8201, an air outlet 8202, a power storage device 8203, and the like. Although FIG. 24 illustrates the case where the power storage device 8203 is provided in the indoor unit 8200, the power storage device 8203 may be provided in the outdoor unit 8204. Alternatively, both the indoor unit 8200 and the outdoor unit 8204 may be provided with the power storage device 8203. The air conditioner can be supplied with electric power from a commercial power source, or can use the electric power stored in the power storage device 8203. In particular, when the power storage device 8203 is provided in both the indoor unit 8200 and the outdoor unit 8204, the power storage device 8203 according to one aspect of the present invention is not used even when the power supply cannot be received from the commercial power source due to a power failure or the like. By using it as an uninterruptible power supply, it is possible to use an air conditioner.

Although FIG. 24 illustrates a separate type air conditioner composed of an indoor unit and an outdoor unit, the integrated air conditioner having the functions of the indoor unit and the outdoor unit in one housing is used. , The power storage device according to one aspect of the present invention can also be used.

In FIG. 24, the electric refrigerator-freezer 8300 is an example of an electronic device using the power storage device 8304 according to one aspect of the present invention. Specifically, the electric freezer / refrigerator 8300 has a housing 8301, a refrigerator door 8302, a freezer door 8303, a power storage device 8304, and the like. In FIG. 24, the power storage device 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 can be supplied with electric power from a commercial power source, or can use the electric power stored in the power storage device 8304. Therefore, even when the power cannot be supplied from the commercial power source due to a power failure or the like, the electric refrigerator-freezer 8300 can be used by using the power storage device 8304 according to one aspect of the present invention as an uninterruptible power supply.

Among the above-mentioned electronic devices, high-frequency heating devices such as microwave ovens and electronic devices such as electric rice cookers require high electric power in a short time. Therefore, by using the power storage device according to one aspect of the present invention as an auxiliary power source for assisting the electric power that cannot be covered by the commercial power source, it is possible to prevent the breaker of the commercial power source from being turned off when the electronic device is used.

In addition, power storage is performed during times when electronic devices are not used, especially when the ratio of the amount of power actually used (called the power usage rate) to the total amount of power that can be supplied by the supply source of commercial power is low. By storing electric power in the device, it is possible to suppress an increase in the electric power usage rate outside the above time zone. For example, in the case of the electric freezer / refrigerator 8300, electric power is stored in the power storage device 8304 at night when the temperature is low and the refrigerating room door 8302 and the freezing room door 8303 are not opened / closed. Then, in the daytime when the temperature rises and the refrigerating room door 8302 and the freezing room door 8303 are opened and closed, the power storage device 8304 can be used as an auxiliary power source to keep the daytime power usage rate low.

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

(Embodiment 5)
In this embodiment, an example of mounting a power storage device on a vehicle is shown.

Further, when the power storage device is mounted on the vehicle, a next-generation clean energy vehicle such as a hybrid electric vehicle (HEV), an electric vehicle (EV), or a plug-in hybrid vehicle (PHEV) can be realized.

FIG. 25 illustrates a vehicle using one aspect of the present invention. The automobile 8400 shown in FIG. 25 (A) is an electric vehicle that uses an electric motor as a power source for traveling. Alternatively, it is a hybrid vehicle in which an electric motor and an engine can be appropriately selected and used as a power source for driving. By using one aspect of the present invention, a vehicle having a long cruising range can be realized. Further, the automobile 8400 has a power storage device. The power storage device can not only drive the electric motor 8406, but also supply electric power to a light emitting device such as a headlight 8401 and a room light (not shown).

Further, the power storage device can supply electric power to display devices such as a speedometer and a tachometer included in the automobile 8400. Further, the power storage device can supply electric power to a semiconductor device such as a navigation system included in the automobile 8400.

The automobile 8500 shown in FIG. 25B can be charged by receiving electric power from an external charging facility by a plug-in method, a non-contact power feeding method, or the like in the power storage device of the automobile 8500. FIG. 25B shows a state in which the power storage device 8024 mounted on the automobile 8500 is being charged from the ground-mounted charging device 8021 via the cable 8022. At the time of charging, the charging method, the standard of the connector, and the like may be appropriately performed by a predetermined method such as CHAdeMO (registered trademark) or combo. The charging device 8021 may be a charging station provided in a commercial facility or a household power source. For example, the plug-in technology can charge the power storage device 8024 mounted on the automobile 8500 by supplying electric power from the outside. Charging can be performed by converting AC power into DC power via a conversion device such as an ACDC converter.

Further, although not shown, it is also possible to mount a power receiving device on a vehicle and supply electric power from a ground power transmission device in a non-contact manner to charge the vehicle. In the case of this non-contact power supply system, by incorporating a power transmission device on the road or the outer wall, it is possible to charge the battery not only while the vehicle is stopped but also while the vehicle is running. Further, the non-contact power feeding method may be used to transmit and receive electric power between vehicles. Further, a solar cell may be provided on the exterior portion of the vehicle to charge the power storage device when the vehicle is stopped or running. An electromagnetic induction method or a magnetic field resonance method can be used for such non-contact power supply.

According to one aspect of the present invention, the cycle characteristics of the power storage device are improved, and the reliability can be improved. Further, according to one aspect of the present invention, the characteristics of the power storage device can be improved, and thus the power storage device itself can be made smaller and lighter. If the power storage device itself can be made smaller and lighter, it will contribute to the weight reduction of the vehicle, and thus the cruising range can be improved. Further, the power storage device mounted on the vehicle can also be used as a power supply source other than the vehicle. In this case, it is possible to avoid using a commercial power source at the peak of power demand.

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

Hereinafter, the present invention will be specifically described with reference to examples. In this embodiment, the result of forming a protective layer surrounding the active material by the method shown in the first embodiment and producing an electrode using the active material will be described. The present invention is not limited to the following examples.

(Formation of a protective layer surrounding the active material)
First, a protective layer surrounding the active material was formed. LiCoO ₂ was used as the active material, and graphene oxide (GO) was used as the raw material for the protective layer. A mixture was formed using a kneader while gradually adding pure water (6.2 ml) to LiCoO ₂ (10 g) and GO (0.205 g). Then, the mixture was dried by heating at 50 ° C. for 12 hours in an air atmosphere.

The dried mixture was crushed using a mortar and then sieved with an opening of 53 μm. In the present specification and the like, the opening represents the size of the gap between the lines.

The above is the method for forming the protective layer that surrounds the active material.

Next, a method of manufacturing the electrode A and the electrode B using LiCoO ₂ having the protective layer formed by the above method will be described. In the electrode A, polyvinylidene fluoride (PVdF) was used as a binder, and N-methylpyrrolidone (NMP) was used as a solvent. Further, in the electrode B, acetylene black (AB) was used as the conductive auxiliary agent, PVdF was used as the binder, and NMP was used as the solvent.

In the method for producing the electrodes shown below, PVdF and NMP are actually prepared by using a solution in which 0.5% (weight) of PVdF is dissolved in NMP (hereinafter referred to as a solution containing PVdf). added.

(Preparation of electrode A)
First, LiCoO ₂ (1.003 g) having a protective layer formed and a solution containing PVdF (0.1618 g) were mixed at 2000 rpm for 20 minutes. A solution containing PVdF (0.0831 g) was added to the mixture, and the mixture was mixed at 2000 rpm for 20 minutes using a kneader. Further, a solution containing PVdF (0.1666 g) was added to the mixture, and the mixture was mixed at 2000 rpm for 15 minutes using a kneader.

Next, the mixture was applied to one side of a sheet-shaped current collector (aluminum) and heated at 80 ° C. for 30 minutes in an atmospheric atmosphere to prepare an electrode B.

(Preparation of electrode B)
First, a solution containing AB (0.0217 g) and PVdF (0.1853 g) was mixed using a kneader for 5 minutes at 2000 rpm. LiCoO ₂ (0.8015 g) having a protective layer formed therein was added to the mixture and mixed at 2000 rpm for 40 minutes using a kneader, and then a solution containing PVdF (0.2365 g) was added and the kneader was used. The mixture was mixed at 2000 rpm for 15 minutes.

Next, the mixture was applied to one side of a sheet-shaped current collector (aluminum) and heated at 80 ° C. for 30 minutes in an atmospheric atmosphere to prepare an electrode B.

FIG. 26 shows the results of observing the structures of the active material layers of the prepared electrodes A and B using a scanning electron microscope (SEM).

FIG. 26A shows a cross-sectional SEM image of the active material layer of the electrode A. As shown in FIG. 26 (A), in the active material layer of the electrode A, the active material 201 was surrounded by the protective layer 202. Further, the active material 201 and the protective layer 202 had a contact area.

FIG. 26B shows a cross-sectional SEM image of the active material layer of the electrode B. As shown in FIG. 26B, in the active material layer of the electrode B, the active material 201 was surrounded by the protective layer 202. Further, the active material 201 and the protective layer 202 had a contact area. Further, the conductive auxiliary agent 203 was present in the active material layer.

The above is the result of forming a protective layer surrounding the active material by the method shown in the first embodiment and manufacturing an electrode using the active material. From this example, it was shown that the protective layer surrounding the active material can be formed by the method shown in the first embodiment.

In this embodiment, the result of forming a protective layer on the active material layer by the method shown in the first embodiment and producing the electrode C using the active material will be described. The present invention is not limited to the following examples.

In the electrode C, PVdF was used as the binder and NMP was used as the solvent. In addition, graphene oxide was used as a layer having a conductive material used for the protective layer on the active material layer.

(Preparation of electrode C)
First, a solution containing LiCoO ₂ , AB, and PVdF is weighed so that LiCoO ₂ : AB: PVdF = 95: 3: 2 (weight ratio), and a mixture having these materials is formed using a kneader. did.

Next, the mixture was applied to one side of a sheet-shaped current collector (aluminum) (20 mg / cm ² ) and heated at 50 ° C. for 120 minutes under a reduced pressure atmosphere to form an active material layer.

Next, graphene oxide (0.08 g) was dispersed in ultra-dehydrated ethanol (8.5 ml), and a mixture was prepared using a kneader. After dipping the active material layer and the current collector into the mixture for 5 seconds, the mixture is placed on a fluororesin sheet and heated at 50 ° C. for about 15 minutes in an air atmosphere three times to activate the current collector and the current collector. An electrode C was created by forming a protective layer surrounding the entire material layer.

The results of observing the side surfaces of the prepared electrodes using SEM are shown with reference to FIG. 27.

FIG. 27A shows an SEM image of the side surface of the electrode C. As shown in FIG. 27, it was found that the surface of the electrode C was covered with the protective layer 204.

FIG. 27B shows, as a comparative example, an SEM image of an electrode on which a protective layer is not formed, which is observed from the side surface. As shown in FIG. 27 (B), the active material layer 205 and the current collector 206 could be observed from the side surface of the electrode on which the protective layer was not formed.

The above is the result of manufacturing an electrode having a protective layer surrounding the current collector and the active material layer by the method shown in the first embodiment. From this example, it was shown that the protective layer surrounding the current collector and the active material layer can be formed by the method shown in the first embodiment.

50 Electrode 51 Collector 52 Active material layer 53 Protective layer 54 Active material 55 Region 56 Protective layer 61 Binder 62 Conductive aid 63 Void 111 Positive electrode 111a Positive electrode 115 Negative electrode 115a Negative electrode 121 Positive current collector 122 Positive electrode active material layer 123 Separator 125 Negative electrode current collector 126 Negative electrode active material layer 130 Electrode assembly 131 Electrode assembly 201 Active material 202 Protective layer 203 Conductive aid 204 Protective layer 205 Active material layer 206 Current collector 300 Storage battery 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive Electrode Collector 306 Positive Electrode Active Material Layer 307 Negative Electrode 308 Negative Electrode Collector 309 Negative Electrode Active Material Layer 310 Separator 500 Storage Battery 501 Positive Electrode Collector 502 Positive Electrode Active Material Layer 503 Positive Electrode 504 Negative Electrode Collector 505 Negative Electrode Active Material Layer 506 Negative Electrode 507 Separator 508 Electrode 509 Exterior 510 Positive electrode lead electrode 511 Negative electrode lead electrode 512 Welding area 514 Sealing part 600 Storage battery 601 Positive electrode cap 602 Battery can 603 Positive electrode terminal 604 Positive electrode 605 Separator 606 Negative electrode 607 Negative electrode terminal 608 Insulation plate 609 Insulation plate 611 PTC element 612 Safety valve mechanism 900 Circuit board 910 Label 911 Terminal 912 Circuit 913 Storage battery 914 Antenna 915 Antenna 916 Layer 917 Layer 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 951 Terminal 952 Terminal 981 Film 982 Film 990 Storage battery 991 Exterior Body 993 Winding body 994 Negative electrode 995 Positive electrode 996 Separator 997 Lead electrode 998 Lead electrode 1700 Curved surface 1701 Flat surface 1702 Curve 1703 Curvature radius 1704 Curvature center 1800 Curvature center 1801 Film 1802 Curvature radius 1803 Film 1804 Curved radius 7100 Portable display device 7101 Housing 7102 Display 7103 Operation button 7104 Power storage device 7200 Mobile information terminal 7201 Housing 7202 Display unit 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output terminal 7207 Icon 7300 Display device 7304 Display unit 7400 Mobile phone 7401 Housing 7402 Display unit 7403 Operation button 7404 External connection port 7405 Speaker 7406 Microphone 7407 Power storage device 7408 Lead electrode 7409 Collector 8000 display Device 8001 Housing 8002 Display 8003 Speaker 8004 Power storage device 8021 Charging device 8022 Cable 8024 Power storage device 8100 Lighting device 8101 Housing 8102 Light source 8103 Power storage device 8104 Ceiling 8105 Side wall 8106 Floor 8107 Window 8200 Indoor unit 8201 Housing 8202 Air outlet 8203 Power storage device 8204 Outdoor unit 8300 Electric refrigerator / freezer 8301 Housing 8302 Refrigerating room door 8303 Freezing room door 8304 Power storage device 8400 Automobile 8401 Headlight 8406 Electric motor 8500 Automobile 9600 Tablet type terminal 9625 Switch 9626 Switch 9627 Power switch 9628 Operation switch 9629 Fastener 9630 Housing 9630a Housing 9630b Housing 9631 Display 9631a Display 9631b Display 9632a Area 9632b Area 9633 Solar cell 9634 Charge / discharge control circuit 9635 Storage unit 9636 DCDC converter 9637 Converter 9638 Operation key 9638 Button 9640 Movable part

Claims (5)

With the current collector,
The active material layer on the current collector and
It has the active material layer and a first protective layer provided so as to surround the current collector.
The active material layer has a particulate active material having a composite oxide having Li and one or more selected from Co or Ni.
The first protective layer is an electrode having a graphene compound. In claim 1,
The active material layer is
With the active substance
It has a second protective layer provided so as to surround the active material, and has.
The second protective layer is an electrode having a graphene compound. In claim 1 or 2,
The graphene compound is an electrode in which graphene or multigraphene is a compound modified into an atomic group having an atom other than carbon or an atom other than carbon . In any one of claims 1 to 3,
The current collector is an electrode having one or more selected from iron, nickel, cobalt, titanium and tantalum. It has a positive electrode, a negative electrode, a separator, and an exterior body.
The positive electrode is
With the current collector,
The active material layer on the current collector and
It has the active material layer and a first protective layer provided so as to surround the current collector.
The active material layer has a particulate active material having a composite oxide having Li and one or more selected from Co or Ni.
The first protective layer is a storage battery having a graphene compound.

Images