JP2016096023A - Power storage device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device having satisfactory cycle characteristics.SOLUTION: A power storage device includes a positive electrode, a negative electrode, and electrolyte. The electrolyte contains a cation and an anion. The cation contains 1-ethyl-2, and 3-dimethyl imidazolium cation shown in a constitutional formula (100).SELECTED DRAWING: Figure 1

Description

One embodiment of the present invention relates to a power storage device and an electronic device.

Note that one embodiment of the present invention is not limited to the above technical field. One embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. One aspect of the present invention relates to a process, machine, manufacturer, or composition (composition of matter). Therefore, the technical field of one embodiment of the invention disclosed in this specification more specifically includes a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, an imaging device, a driving method thereof, or a manufacturing method thereof. The method can be mentioned as an example.

Note that in this specification, a power storage device refers to all elements and devices having a power storage function. For example, a storage battery (also referred to as a secondary battery) such as a lithium ion secondary battery, a lithium ion capacitor, and an electric double layer capacitor are included.

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, lithium-ion secondary batteries with high output and high energy density are portable information terminals such as mobile phones, smartphones or notebook computers, portable music players, digital cameras, medical devices, hybrid vehicles (HEV), electric With the development of the semiconductor industry, such as next-generation clean energy vehicles such as automobiles (EV) or plug-in hybrid vehicles (PHEV), the demand has rapidly expanded, and the modern information society as a source of rechargeable energy It has become indispensable to.

Thus, lithium ion secondary batteries are used in various fields or applications. Among them, characteristics required for the lithium ion secondary battery include high energy density, excellent cycle characteristics, and safety in various operating environments.

Many of the lithium ion secondary batteries that are widely used have a nonaqueous electrolyte (also referred to as an electrolyte) that includes a nonaqueous solvent and a lithium salt having lithium ions. And as an organic solvent often used for the said non-aqueous electrolyte, there exist organic solvents, such as ethylene carbonate with a high dielectric constant and excellent ionic conductivity.

However, the organic solvent has volatility and a low flash point, and when this organic solvent is used in a lithium ion secondary battery, the internal temperature of the lithium ion secondary battery due to internal short circuit or overcharge is reduced. There is a possibility that the lithium ion secondary battery will burst or ignite due to the rise.

In view of the above, it has been studied to use an ionic liquid (also referred to as a room temperature molten salt) that is flame retardant and hardly volatile as a solvent for a non-aqueous electrolyte of a lithium ion secondary battery. For example, an ionic liquid containing an ethylmethylimidazolium (EMI) cation, an ionic liquid containing an N-methyl-N-propylpyrrolidinium (P13) cation, or an N-methyl-N-propylpiperidinium (PP13) cation. There are ionic liquids and the like (see Patent Document 1).

Further, a lithium ion secondary battery using an ionic liquid having a low viscosity, a low melting point, and a high conductivity by improving an anionic component and a cationic component of the ionic liquid is disclosed (see Patent Document 2).

JP 2003-331918 A International Publication No. 2005/63773

Development of a lithium ion secondary battery leaves room for improvement in various aspects such as charge / discharge characteristics, cycle characteristics, reliability, safety, or cost.

An object of one embodiment of the present invention is to provide a power storage device with favorable cycle characteristics. Another object of one embodiment of the present invention is to provide a highly safe power storage device. Another object of one embodiment of the present invention is to provide a power storage device with reduced irreversible capacity. Another object of one embodiment of the present invention is to provide a highly reliable power storage device. Another object of one embodiment of the present invention is to provide a power storage device with a long lifetime.

Another object of one embodiment of the present invention is to provide a power storage device with high capacity. Another object of one embodiment of the present invention is to provide a power storage device with a wide usable temperature range. Another object of one embodiment of the present invention is to provide a high-performance power storage device. Another object of one embodiment of the present invention is to provide a novel power storage device.

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

One embodiment of the present invention includes a positive electrode, a negative electrode, and an electrolytic solution, and the electrolytic solution includes a first cation and an anion, and the first cation is represented by Structural Formula (100). It is.

In the above configuration, the electrolytic solution preferably has an alkali metal salt. In particular, a lithium salt is suitable as the alkali metal salt.

In each of the above structures, the anion is a monovalent amide anion, a monovalent methide anion, a fluorosulfonate anion, a fluoroalkylsulfonate anion, a tetrafluoroborate anion, a perfluoroalkylborate anion, a hexafluorophosphate anion, or It preferably contains any one of perfluoroalkyl phosphate anions. In particular, the anion preferably includes a bis (fluorosulfonyl) amide anion or a bis (trifluoromethanesulfonyl) amide anion.

In each of the above configurations, the negative electrode preferably contains carbon.

Note that the electrolytic solution may be decomposed by charging or discharging of the power storage device, and the decomposition product may form a film on the surface of the negative electrode. The coating can suppress the decomposition of the electrolytic solution, but due to the formation of the coating, an irreversible capacity is generated and a part of the discharge capacity is lost. Therefore, in one embodiment of the present invention, it is preferable to artificially form a film on the negative electrode in advance before charging or discharging the power storage device. By providing an artificial film on the surface of the negative electrode in advance, decomposition of the electrolytic solution and the like can be suppressed, and a reduction in the capacity of the power storage device can be suppressed.

In each of the above configurations, for example, the negative electrode preferably includes carboxymethyl cellulose and styrene-butadiene rubber. Carboxymethyl cellulose and styrene-butadiene rubber can function as a binder. By using carboxymethyl cellulose and styrene-butadiene rubber for the negative electrode, an artificial film can be formed on the surface of the negative electrode.

In each of the above structures, the positive electrode preferably includes graphene. Graphene can function as a conductive additive. By using graphene for the electrode, the density of the electrode can be improved and the conductivity of the electrode can be improved.

In each of the above configurations, the electrolytic solution preferably has a second cation. As the second cation, an aliphatic onium cation such as a quaternary ammonium cation, a tertiary sulfonium cation, or a quaternary phosphonium cation, or an aromatic cation such as an imidazolium cation or a pyridinium cation can be used. In particular, the second cation is preferably an imidazolium cation.

One embodiment of the present invention is an electronic device including the power storage device having any of the above structures and a display device, operation buttons, an external connection port, a speaker, or a microphone.

According to one embodiment of the present invention, a power storage device with favorable cycle characteristics can be provided. Alternatively, according to one embodiment of the present invention, a highly safe power storage device can be provided. Alternatively, according to one embodiment of the present invention, the irreversible capacity of a power storage device can be reduced. Alternatively, according to one embodiment of the present invention, a highly reliable power storage device can be provided. Alternatively, according to one embodiment of the present invention, a power storage device with a long lifetime can be provided.

Alternatively, according to one embodiment of the present invention, a power storage device with a large capacity can be provided. Alternatively, according to one embodiment of the present invention, a power storage device with a wide usable temperature range can be provided. Alternatively, according to one embodiment of the present invention, a high-performance power storage device can be provided. Alternatively, according to one embodiment of the present invention, a novel power storage device can be provided.

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

FIG. 6 illustrates an example of a power storage device and an example of an electrode. FIG. 9 illustrates an example of a power storage device. FIG. 9 illustrates an example of a power storage device. FIG. 10 illustrates an example of operation of a power storage device. FIG. 9 illustrates an example of a power storage device. 10A and 10B illustrate an example of a method for manufacturing a power storage device. 10A and 10B illustrate an example of a method for manufacturing a power storage device. 10A and 10B illustrate an example of a method for manufacturing a power storage device. The figure which shows an example of an active material layer. FIG. 9 illustrates an example of a power storage device. FIG. 9 illustrates an example of a power storage device. FIG. 9 illustrates an example of a power storage device. The figure which shows an example of a cylindrical storage battery. The figure which shows an example of a coin-type storage battery. The figure which shows an example of an electrical storage system. The figure which shows an example of an electrical storage system. The figure which shows an example of an electrical storage system. FIG. 11 is a block diagram illustrating an example of a power storage device. 1 is a conceptual diagram illustrating one embodiment of the present invention. FIG. 10 is a circuit diagram illustrating one embodiment of the present invention. FIG. 10 is a circuit diagram illustrating one embodiment of the present invention. 1 is a conceptual diagram illustrating one embodiment of the present invention. FIG. 10 is a block diagram illustrating one embodiment of the present invention. 6 is a flowchart illustrating one embodiment of the present invention. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device. The figure which shows the cycle characteristic of the electrical storage apparatus of an Example. The figure which shows the rate characteristic of the electrical storage apparatus of an Example.

Embodiments 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 modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

Note that in structures of the invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and description thereof is not repeated. In addition, in the case where the same function is indicated, the hatch pattern is the same, and there is a case where no reference numeral is given.

In addition, the position, size, range, and the like of each component illustrated in the drawings and the like may not represent the actual position, size, range, or the like for easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, or the like disclosed in the drawings and the like.

Note that in this specification and the like, ordinal numbers given as first, second, and the like are used for convenience and do not indicate the order of steps or the order of lamination. Therefore, for example, the description can be made by appropriately replacing “first” with “second” or “third”. In addition, the ordinal numbers described in this specification and the like may not match the ordinal numbers used to specify one embodiment of the present invention.

Note that the terms “film” and “layer” can be interchanged with each other depending on circumstances or circumstances. For example, the term “conductive layer” may be changed to the term “conductive film”. Alternatively, for example, the term “insulating film” may be changed to the term “insulating layer” in some cases.

Note that in this specification and the like, both the positive electrode and the negative electrode for a power storage device are sometimes referred to as an electrode. In this case, the electrode indicates at least one of a positive electrode and a negative electrode.

Here, the charge rate and the discharge rate will be described. For example, when charging a storage battery with a capacity X [Ah] at a constant current, the charging rate 1C is a current value I [A] at which charging is completed in exactly one hour. For example, a charging rate 0.2C Is I / 5 [A] (that is, the current value at which charging is completed in just 5 hours). Similarly, the discharge rate 1C is a current value I [A] that completes the discharge in just one hour. For example, the discharge rate 0.2C is I / 5 [A] (that is, exactly five hours). The current value at which discharge ends.

Here, the active material refers only to a material related to insertion / extraction of ions as carriers, but in this specification and the like, in addition to the material that is originally an “active material”, a conductive auxiliary agent, a binder, etc. What is included is also called an active material layer.

(Embodiment 1)
In this embodiment, a power storage device of one embodiment of the present invention will be described with reference to FIGS.

In this embodiment, a lithium ion secondary battery is described as an example; however, the power storage device of one embodiment of the present invention is not limited thereto. One aspect of the present invention is a battery, a primary battery, a secondary battery, a lithium air battery, a lead storage battery, a lithium ion polymer secondary battery, a nickel / hydrogen storage battery, a nickel / cadmium storage battery, a nickel / iron storage battery, a nickel / zinc storage battery, The present invention may be applied to silver oxide / zinc storage batteries, solid batteries, air batteries, capacitors, lithium ion capacitors, and the like.

FIG. 1A illustrates a battery cell 500 which is a power storage device of one embodiment of the present invention. In FIG. 1A, a thin storage battery is shown as an example of the battery cell 500; however, the power storage device of one embodiment of the present invention is not limited thereto. Various shapes and forms can be applied to the power storage device of one embodiment of the present invention, and an example thereof will be described in detail in Embodiment 2.

As illustrated in FIG. 1A, the battery cell 500 includes a positive electrode 503, a negative electrode 506, a separator 507, and an exterior body 509. The battery cell 500 may include a positive electrode lead electrode 510 and a negative electrode lead electrode 511.

2A and 2B show examples of cross-sectional views taken along one-dot chain line A1-A2 in FIG. 2A and 2B show cross-sectional structures of a battery cell 500 manufactured using one set of a positive electrode 503 and a negative electrode 506, respectively.

As shown in FIGS. 2A and 2B, the battery cell 500 includes a positive electrode 503, a negative electrode 506, a separator 507, an electrolytic solution 508, and an exterior body 509. The separator 507 is sandwiched between the positive electrode 503 and the negative electrode 506. The exterior body 509 is filled with the electrolytic solution 508.

The positive electrode 503 includes a positive electrode active material layer 502 and a positive electrode current collector 501. The negative electrode 506 includes a negative electrode active material layer 505 and a negative electrode current collector 504. The active material layer may be formed on one side or both sides of the current collector. The separator 507 is located between the positive electrode current collector 501 and the negative electrode current collector 504.

The battery cell should just have one or more each of a positive electrode and a negative electrode. For example, the battery cell may have a stacked structure including a plurality of positive electrodes and a plurality of negative electrodes.

FIG. 3A illustrates another example of a cross-sectional view taken along the dashed-dotted line A1-A2 in FIG. FIG. 3B is a cross-sectional view taken along dashed-dotted line B1-B2 in FIG.

FIGS. 3A and 3B show a cross-sectional structure of a battery cell 500 manufactured using a plurality of sets of positive electrodes 503 and negative electrodes 506. The number of electrode layers that the battery cell 500 has is not limited. When the number of electrode layers is large, a power storage device having a larger capacity can be obtained. Further, when the number of electrode layers is small, the power storage device can be thinned and has excellent flexibility.

3A and 3B, two positive electrodes 503 having a positive electrode active material layer 502 on one side of the positive electrode current collector 501 and positive electrodes 503 having a positive electrode active material layer 502 on both sides of the positive electrode current collector 501 are shown. An example in which two negative electrodes 506 having a negative electrode active material layer 505 on both surfaces of a negative electrode current collector 504 are used is shown. That is, the battery cell 500 includes six positive electrode active material layers 502 and six negative electrode active material layers 505.

Here, the operation of the battery cell 500 will be described with reference to FIGS. Here, the case where the battery cell 500 is a lithium ion secondary battery is described as an example. Specifically, a lithium ion secondary battery using LiFePO ₄ as the positive electrode active material and graphite as the negative electrode active material will be described as an example.

FIG. 4A illustrates a connection configuration between the battery cell 500 and the charger 1122 in the case of charging. The reaction that occurs at the positive electrode during charging is shown in Reaction Formula (1).

In addition, the reaction that occurs at the negative electrode during charging is shown in Reaction Formula (2) (see Li ⁺ in FIG. 4A).

Next, discharge will be described. FIG. 4B shows a connection configuration between the battery cell 500 and the charger 1123 in the case of discharging. The reaction occurring at the positive electrode during discharge is shown in reaction formula (3).

In addition, the reaction that occurs at the negative electrode during discharge is shown in reaction formula (4).

In the negative electrode, a reaction other than the reaction represented by Formula (2) may occur during charging. Similarly, in the negative electrode, a reaction other than the reaction represented by Formula (4) may occur during discharge.

For example, the electrolytic solution may be decomposed on the surface of the electrode. The electrolytic solution may decompose on the electrode surface at the potential of the battery reaction. Particularly in the negative electrode, the battery reaction potential is low and reductive decomposition of the electrolytic solution is likely to occur. Such a decomposition reaction is often an irreversible reaction. Therefore, it may lead to a loss of capacity of the battery cell.

For example, when an ionic liquid is used as the solvent of the electrolytic solution, cations of the ionic liquid may be inserted between the layers of the active material. This reaction is also often an irreversible reaction.

Further, the irreversible reaction between the negative electrode current collector and the electrolytic solution or a decomposition product of the electrolytic solution may cause the negative electrode current collector to elute and deposit the components of the negative electrode current collector on the surface of the negative electrode active material layer. is there. Therefore, it becomes a factor which reduces the capacity | capacitance of a battery cell.

For example, when the irreversible reaction described above occurs during charging, the capacity during discharging becomes smaller than the capacity during charging.

Moreover, when the above irreversible reaction occurs at the time of discharge, compared with the capacity at the time of discharge, the capacity at the time of charge in the next charge / discharge cycle may be reduced. That is, if an irreversible reaction continues to occur, the capacity may gradually decrease with the charge / discharge cycle.

Here, the electrolytic solution has an electrolyte and a solvent. In the power storage device of one embodiment of the present invention, one or more ionic liquids are used as a solvent for the electrolytic solution. The ionic liquid has one or more types of cations and one or more types of anions. Since the ionic liquid exhibits flame retardancy, the safety of the power storage device can be improved.

Below, the irreversible reaction which arises when using an ionic liquid as a solvent of electrolyte solution is demonstrated in detail.

Since the cation and anion of the ionic liquid have a charge, for example, an electric double layer can be formed on the electrode surface and the like, and can be used for a power storage device such as an electric double layer capacitor.

On the other hand, cations and anions included in the ionic liquid may be decomposed on the electrode surface. Since the cation and the anion each have an electric charge, it is considered that the cation and the anion are likely to exist near the electrode surface (for example, the surface of the active material layer or the current collector) as compared with a molecule such as an organic solvent. For this reason, a decomposition reaction of cations or anions may easily occur on the electrode surface. When charges are consumed by the decomposition reaction of cations or anions, the battery reaction of carrier ions (for example, lithium ions) may be inhibited, and the charge / discharge capacity may be reduced. Further, as a result of the electrolytic solution being decomposed on the surface of the active material layer or the current collector, the irreversible capacity may increase, and the capacity may decrease due to the charge / discharge cycle.

Further, for example, a cation or an anion of the ionic liquid may be inserted between layers of an intercalation compound typified by graphite. Further, cations and anions inserted between the layers may be decomposed or desorbed thereafter.

These irreversible reactions are considered to occur in parallel with the reactions of the formulas (1) to (4). Compared with these irreversible reactions, it is preferable to create an environment in which the normal reaction of the battery operation, that is, the reactions of Equations (1) to (4) are more likely to occur, in order to increase the capacity of the battery cell.

Thus, in one embodiment of the present invention, 1-ethyl-2,3-dimethylimidazolium cation (abbreviation: 2MeEMI), which is a kind of imidazolium cation, is used. The structural formula (100) of 2MeEMI is shown below.

An imidazolium cation such as 1-ethyl-3-methylimidazolium cation has a relatively low viscosity and a high conductivity of ions (for example, lithium ions). Therefore, a power storage device with a high charge / discharge rate can be realized.

When an ionic liquid using an imidazolium cation is used in a power storage device, the resistance of the ionic liquid (more specifically, an electrolytic solution having the ionic liquid) is increased even in a low temperature environment (particularly 0 ° C. or lower). It is difficult to suppress a decrease in charge / discharge rate. Therefore, a power storage device that can operate in a low-temperature environment can be realized. In addition, a power storage device with a wide usable temperature range can be realized.

On the other hand, an imidazolium cation may be easily reductively decomposed on the surface of an active material or a current collector that is a constituent material of a power storage device because of a high reduction potential. As a result, the irreversible capacity may increase. Moreover, the capacity | capacitance fall accompanying a charging / discharging cycle may be caused.

Although 2MeEMI used in one embodiment of the present invention is a kind of imidazolium cation, its capacity is unlikely to decrease with charge / discharge cycles.

As will be described later in Example 1, 2MeEMI can significantly suppress a decrease in capacity associated with a charge / discharge cycle as compared to 1-ethyl-3-methylimidazolium cation.

In 2MeEMI, by substituting the 2-position proton of the imidazolium ring in the 1-ethyl-3-methylimidazolium cation with a methyl group having low reactivity, the decomposition reaction of the electrolytic solution or the current collector (for example, copper) It is considered that the elution of selenium is suppressed and irreversible reaction is suppressed.

Thus, in one embodiment of the present invention, 2MeEMI having a substituent at the 2-position as well as the 1-position and the 3-position of the imidazolium ring is used. Thereby, the decomposition reaction of the electrolytic solution generated on the surface of the active material layer or the current collector can be suppressed, and the irreversible reaction can be made difficult to occur. Therefore, the capacity | capacitance fall accompanying the charging / discharging cycle of an electrical storage apparatus can be suppressed. Moreover, the irreversible capacity | capacitance of an electrical storage apparatus can be reduced and charging / discharging capacity | capacitance can be enlarged.

The cation used in one embodiment of the present invention is not limited to 2MeEMI. For example, 2MeEMI and other cations may be used in combination. At this time, of the cations contained in the ionic liquid, either 2MeEMI and other cations may be higher.

As the cation, an aliphatic onium cation such as a quaternary ammonium cation, a tertiary sulfonium cation, or a quaternary phosphonium cation, or an aromatic cation such as an imidazolium cation or a pyridinium cation may be used.

For example, the use of an aliphatic onium cation such as a quaternary ammonium cation, a tertiary sulfonium cation, or a quaternary phosphonium cation may reduce the reduction potential and reduce the irreversible capacity of the power storage device.

For example, when an ionic liquid containing an aromatic cation such as an imidazolium cation is used, the viscosity may be low and the charge / discharge rate of the power storage device may be increased. Alternatively, a power storage device with a wide usable temperature range may be realized.

For example, in one embodiment of the present invention, both 2MeEMI and 1-ethyl-3-methylimidazolium cation may be used.

As the aromatic cation, for example, a cation containing a 5-membered heteroaromatic ring is preferable. Examples of the cation containing a 5-membered heteroaromatic ring include a benzimidazolium cation, a benzoxazolium cation, and a benzothiazolium cation. Examples of the cation containing a 5-membered heteroaromatic ring that is a monocyclic compound include oxazolium cation, thiazolium cation, isoxazolium cation, isothiazolium cation, imidazolium cation, and pyrazolium cation. . In view of the stability of the compound, viscosity and ionic conductivity, and ease of synthesis, it is preferably a cation containing a 5-membered heteroaromatic ring, which is a monocyclic compound, and the imidazolium cation is expected to decrease in viscosity. Since it can do, it is more preferable.

Examples of the anion include a monovalent amide anion, a monovalent methide anion, a fluorosulfonate anion (SO ₃ F ⁻ ), a fluoroalkylsulfonate anion, a tetrafluoroborate anion (BF ₄ ⁻ ), and a perfluoroalkylborate. Examples thereof include an anion, a hexafluorophosphate anion (PF ₆ ⁻ ), and a perfluoroalkyl phosphate anion.

The monovalent amide _{anion, (C n F 2n + 1} SO 2) 2 N - (n = 0 to 3), the monovalent cyclic amide _{anion, (CF 2 SO 2) 2} N - , and the like .

The monovalent methide _{anion, (C n F 2n + 1} SO 2) 3 C - (n = 0 to 3), the monovalent cyclic methide ^{_{anion, (CF 2 SO 2) 2}} C - (CF 3 SO 2 )and so on.

Examples of the fluoroalkylsulfonic acid anion include (C _m F _{2m + 1} SO ₃ ) ⁻ (m = 0 or more and 4 or less). The perfluoroalkyl borate _{anion, {BF n (C m H} k F 2m + 1-k) 4-n} - (n = 0 to 3, m = 1 to 4, k = 0 or 2m or less) such as There is. The perfluoroalkyl phosphate _{anion, {PF n (C m H} k F 2m + 1-k) 6-n} - (n = 0 to 5, m = 1 to 4, k = 0 or 2m or less) such as There is. The anion is not limited to these.

As the anion, a bis (fluorosulfonyl) amide (abbreviation: FSA) anion or a bis (trifluoromethanesulfonyl) amide (abbreviation: TFSA) anion is preferably used. In particular, when graphite is used for an electrode, good charge / discharge characteristics can be obtained.

Moreover, you may mix and use an aprotic organic solvent with the above-mentioned ionic liquid as a solvent of electrolyte solution. Examples of the aprotic organic solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate ( DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, benzo One kind of nitrile, tetrahydrofuran, sulfolane, sultone, etc., or two or more kinds thereof can be used in any combination and ratio.

In addition, additives such as vinylene carbonate (VC), propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bisoxalate borate (LiBOB) may be added to the electrolytic solution. . The concentration of the additive may be 0.1 wt% or more and 5 wt% or less.

As the electrolytes dissolved in the above solvent, when using a lithium carrier ion, e.g. _{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 (FSO ₂ ) ₂ , Lithium salt such as LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₄ F ₉ SO ₂ ) (CF ₃ SO ₂ ), LiN (C ₂ F ₅ SO ₂ ) ₂ , or two or more of these Can be used in any combination and ratio. Further, the concentration of the electrolyte is preferably higher, for example, 0.8 mol / kg or more is preferable, and 1.5 mol / kg or more is more preferable.

Alternatively, lithium bis (fluorosulfonyl) amide (abbreviation: LiFSA) or lithium bis (trifluoromethanesulfonyl) amide (abbreviation: LiTFSA) may be used as the electrolyte. An electrolytic solution using LiFSA or LiTFSA as an electrolyte can suppress elution of a metal in a positive electrode active material in a battery reaction of a power storage device. Therefore, deterioration of the positive electrode active material is suppressed, and metal deposition on the surface of the negative electrode is also suppressed, so that a power storage device with low capacity deterioration and good cycle characteristics can be obtained.

Note that an electrolytic solution using LiFSA or LiTFSA as an electrolyte may react with the positive electrode current collector to corrode the positive electrode current collector. In order to prevent such corrosion, it is preferable to add several wt% LiPF ₆ to the electrolytic solution. This is because a nonconductive film is formed on the surface of the positive electrode current collector, and the nonconductive film suppresses the reaction between the electrolytic solution and the positive electrode current collector. However, in order not to dissolve the positive electrode active material layer, the concentration of LiPF ₆ is 10 wt% or less, preferably 5 wt% or less, more preferably 3 wt% or less.

As the electrolyte, an alkali metal (for example, sodium or potassium) or an alkaline earth metal (for example, calcium, strontium, barium, beryllium, magnesium, or the like) may be used instead of lithium in the lithium salt.

Further, as the electrolytic solution, it is preferable to use a highly purified electrolytic solution having a small content of elements other than the constituent elements of the granular dust and 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.

Alternatively, a gel electrolyte obtained by swelling a polymer with an electrolytic solution may be used. Examples of the gel electrolyte (polymer gel electrolyte) include those using a host polymer as a carrier and containing the above-described electrolytic solution.

Examples of host polymers are described below. As the host polymer, for example, a polymer having a polyalkylene oxide structure such as polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), polyacrylonitrile, 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 formed polymer may have a porous shape.

Moreover, a polymerizing agent or a crosslinking agent may be added to the electrolytic solution to gel the electrolytic solution. For example, the ionic liquid itself may be polymerized by introducing a polymerizable functional group into a cation or anion constituting the ionic liquid and polymerizing them using a polymerization initiator. In this way, the polymerized ionic liquid may be gelled with a crosslinking agent.

Further, in combination with the electrolytic solution, a solid electrolyte having an inorganic material such as sulfide or oxide, or a solid electrolyte having a polymer material such as PEO (polyethylene oxide) may be used. For example, a solid electrolyte may be formed on the surface of the active material layer. Moreover, when using it combining a solid electrolyte and electrolyte solution, installation of a separator or a spacer may become unnecessary.

Moreover, the safety | security with respect to a liquid leakage property etc. increases by using the polymeric material gelatinized as a solvent of electrolyte solution. In addition, the power storage device can be reduced in thickness and weight. Typical examples of the polymer material to be gelated include silicone gel, acrylic gel, acrylonitrile gel, polyethylene oxide, polypropylene oxide, and fluorine-based polymer.

For example, one embodiment of the present invention includes a positive electrode, a negative electrode, and an electrolyte, and the electrolyte includes a compound (cation) represented by the above structural formula (100). It may be solid.

Next, an external view of the positive electrode 503 is shown in FIG. The positive electrode 503 includes a positive electrode current collector 501 and a positive electrode active material layer 502.

FIG. 1C shows an external view of the negative electrode 506. The negative electrode 506 includes a negative electrode current collector 504 and a negative electrode active material layer 505.

Here, the positive electrode 503 and the negative electrode 506 preferably have a tab region in order to electrically connect a plurality of stacked positive electrodes or a plurality of negative electrodes. Moreover, it is preferable to electrically connect the lead electrode to the tab region.

As illustrated in FIG. 1B, the positive electrode 503 preferably includes a tab region 281. A part of the tab region 281 is preferably welded to the positive electrode lead electrode 510. The tab region 281 preferably has a region where the positive electrode current collector 501 is exposed, and the contact resistance can be further reduced by welding the positive electrode lead electrode 510 to a region where the positive electrode current collector 501 is exposed. 1B illustrates an example in which the positive electrode current collector 501 is exposed in the entire region of the tab region 281, the tab region 281 may include the positive electrode active material layer 502 in a part thereof.

As illustrated in FIG. 1C, the negative electrode 506 preferably includes a tab region 282. A part of the tab region 282 is preferably welded to the negative electrode lead electrode 511. The tab region 282 preferably has a region where the negative electrode current collector 504 is exposed, and the contact resistance can be further reduced by welding the negative electrode lead electrode 511 to a region where the negative electrode current collector 504 is exposed. 1C illustrates an example in which the negative electrode current collector 504 is exposed in the entire region of the tab region 282, the tab region 282 may include the negative electrode active material layer 505 in a part thereof.

Note that FIG. 1A illustrates an example in which the end portions of the positive electrode 503 and the negative electrode 506 are substantially aligned; however, the positive electrode 503 may have a portion located outside the end portion of the negative electrode 506. .

In the battery cell 500, the smaller the area of the negative electrode 506 that does not overlap the positive electrode 503, the better.

FIG. 2A illustrates an example in which the end portion of the negative electrode 506 is positioned inside the positive electrode 503. With such a structure, the entire area of the negative electrode 506 can be overlapped with the positive electrode 503, or the area of the negative electrode 506 that does not overlap with the positive electrode 503 can be reduced.

Alternatively, in the battery cell 500, the areas of the positive electrode 503 and the negative electrode 506 are preferably substantially the same. For example, the areas of the positive electrode 503 and the negative electrode 506 that face each other with the separator 507 interposed therebetween are preferably substantially the same. For example, the area of the positive electrode active material layer 502 and the area of the negative electrode active material layer 505 that face each other with the separator 507 interposed therebetween is preferably substantially the same.

For example, as shown in FIGS. 3A and 3B, the area of the surface of the positive electrode 503 on the separator 507 side and the area of the surface of the negative electrode 506 on the separator 507 side are preferably substantially the same. By making the area of the surface of the positive electrode 503 on the negative electrode 506 side substantially the same as the area of the surface of the negative electrode 506 on the positive electrode 503 side, the area that does not overlap the positive electrode 503 of the negative electrode 506 is reduced (or ideally eliminated). This is preferable because the irreversible capacity of the battery cell 500 can be reduced. 3A and 3B, the surface area of the positive electrode active material layer 502 on the separator 507 side and the surface area of the negative electrode active material layer 505 on the separator 507 side are approximately the same. preferable.

As shown in FIGS. 3A and 3B, it is preferable that the end of the positive electrode 503 and the end of the negative electrode 506 are substantially aligned. In addition, it is preferable that end portions of the positive electrode active material layer 502 and the negative electrode active material layer 505 are substantially aligned.

FIG. 2B illustrates an example in which the end portion of the positive electrode 503 is positioned inside the negative electrode 506. With such a structure, the entire area of the positive electrode 503 can be overlapped with the negative electrode 506, or the area of the positive electrode 503 can be reduced in area not overlapping with the negative electrode 506. When the end portion of the negative electrode 506 is positioned inside the end portion of the positive electrode 503, current may concentrate on the end portion of the negative electrode 506. For example, when current concentrates on part of the negative electrode 506, lithium may be deposited on the negative electrode 506. By reducing the area of the positive electrode 503 that does not overlap with the negative electrode 506, current concentration on a part of the negative electrode 506 can be suppressed. Thereby, for example, the deposition of lithium on the negative electrode 506 can be suppressed, which is preferable.

As shown in FIG. 1A, the positive electrode lead electrode 510 is preferably electrically connected to the positive electrode 503. Similarly, the negative electrode lead electrode 511 is preferably electrically connected to the negative electrode 506. The positive electrode lead electrode 510 and the negative electrode lead electrode 511 are exposed to the outside of the exterior body 509 and function as terminals for obtaining electrical contact with the outside.

Alternatively, the positive electrode current collector 501 and the negative electrode current collector 504 can also serve as terminals for obtaining electrical contact with the outside. In that case, a part of the positive electrode current collector 501 and the negative electrode current collector 504 may be disposed so as to be exposed to the outside from the exterior body 509 without using the lead electrode.

In FIG. 1A, the positive electrode lead electrode 510 and the negative electrode lead electrode 511 are arranged on the same side of the battery cell 500. However, as shown in FIG. The battery cells 500 may be arranged on different sides. As described above, the power storage device of one embodiment of the present invention has a high degree of design freedom because lead electrodes can be freely arranged. Thus, the degree of freedom in designing a product using the power storage device of one embodiment of the present invention can be increased. In addition, productivity of a product using the power storage device of one embodiment of the present invention can be increased.

Next, an example of a method for manufacturing the battery cell 500 will be described with reference to FIGS.

First, the positive electrode 503, the negative electrode 506, and the separator 507 are stacked. Specifically, a separator 507 is disposed on the positive electrode 503. Thereafter, the negative electrode 506 is disposed on the separator 507. When two or more pairs of positive and negative electrodes are used, a separator 507 is further disposed on the negative electrode 506, and then the positive electrode 503 is disposed. In this manner, the positive electrode 503 and the negative electrode 506 are alternately stacked while the separator 507 is sandwiched between the positive electrode 503 and the negative electrode 506.

Alternatively, the separator 507 may be formed in a bag shape. It is preferable to wrap the electrode with the separator 507 because the electrode is less likely to be damaged during the manufacturing process.

First, the positive electrode 503 is disposed on the separator 507. Next, the separator 507 is folded at a portion indicated by a broken line in FIG. 6A, and the positive electrode 503 is sandwiched between the separators 507. Note that although the example in which the positive electrode 503 is sandwiched between the separators 507 has been described here, the negative electrode 506 may be sandwiched between the separators 507.

Here, it is preferable that the outer peripheral portion of the separator 507 outside the positive electrode 503 is joined to form the separator 507 in a bag shape (or envelope shape). Joining of the outer peripheral portion of the separator 507 may be performed using an adhesive or the like, or may be performed by ultrasonic welding or fusion by heating.

In this embodiment, polypropylene is used as the separator 507, and the outer peripheral portion of the separator 507 is joined by heating. A joint portion 514 is illustrated in FIG. In this way, the positive electrode 503 can be covered with the separator 507.

Next, as illustrated in FIG. 6B, the negative electrodes 506 and the positive electrodes 503 covered with the separators are alternately stacked. In addition, a positive electrode lead electrode 510 and a negative electrode lead electrode 511 having the sealing layer 115 are prepared.

Next, as illustrated in FIG. 7A, the positive electrode lead electrode 510 having the sealing layer 115 is connected to the tab region 281 of the positive electrode 503. FIG. 7B shows an enlarged view of the connection portion. Ultrasonic waves are applied while applying pressure to the joint portion 512 to electrically connect the tab region 281 of the positive electrode 503 and the positive electrode lead electrode 510 (ultrasonic welding). At this time, a curved portion 513 may be provided in the tab region 281.

By providing the curved portion 513, it is possible to relieve stress generated by applying force from the outside after the battery cell 500 is manufactured. Therefore, the reliability of the battery cell 500 can be improved.

The tab region 282 of the negative electrode 506 and the negative electrode lead electrode 511 can be electrically connected using the same method.

Next, the positive electrode 503, the negative electrode 506, and the separator 507 are disposed over the exterior body 509.

Next, the exterior body 509 is bent at a portion indicated by a broken line near the center of the exterior body 509 in FIG.

FIG. 8 shows a portion where the outer periphery of the exterior body 509 is joined by thermocompression bonding as a joint portion 118. The outer peripheral part of the exterior body 509 other than the introduction port 119 for containing the electrolytic solution 508 is joined by thermocompression bonding. At the time of thermocompression bonding, the sealing layer provided on the lead electrode can be melted to fix the lead electrode and the exterior body 509. In addition, adhesion between the outer package 509 and the lead electrode can be improved.

Then, a desired amount of the electrolytic solution 508 is put into the exterior body 509 from the introduction port 119 under a reduced pressure atmosphere or an inert gas atmosphere. Finally, the inlet 119 is joined by thermocompression bonding. Thus, the battery cell 500 which is a thin storage battery can be produced.

Aging is preferably performed after the battery cell 500 is manufactured. An example of the aging condition will be described below. First, charging is performed at a rate of 0.001C to 0.2C. The temperature may be, for example, room temperature or higher and 50 ° C. or lower. At this time, when the electrolytic solution is decomposed and gas is generated, if the gas accumulates in the cell, a region where the electrolytic solution cannot contact the electrode surface is generated. That is, this corresponds to a reduction in the effective reaction area of the electrode and an increase in the effective current density.

When the current density becomes excessively high, a voltage drop occurs according to the resistance of the electrode, and lithium is inserted into the graphite, and at the same time, lithium is deposited on the graphite surface. This lithium deposition may lead to a decrease in capacity. For example, if a film or the like grows on the surface after lithium is deposited, lithium deposited on the surface cannot be re-eluted, and lithium that does not contribute to the capacity is generated. Further, when the deposited lithium physically collapses and loses conduction with the electrode, lithium that does not contribute to the capacity is also generated. Therefore, it is preferable to degas before the potential of the electrode reaches the lithium potential due to a voltage drop.

In the case of degassing, for example, a part of the outer package of a thin storage battery may be cut and opened. When the exterior body is expanded by gas, it is preferable to arrange the shape of the exterior body again. Moreover, you may add electrolyte solution as needed before resealing.

In addition, after degassing, the battery is kept in a charged state at a temperature higher than room temperature, preferably 30 ° C. or more and 60 ° C. or less, more preferably 35 ° C. or more and 50 ° C. or less, for example, for 1 hour or more and 100 hours or less. May be. During the first charge, the electrolytic solution decomposed on the surface forms a film. Therefore, for example, a case where the formed film is densified by holding at a temperature higher than room temperature after degassing may be considered.

In addition, for example, in a power storage device mounted on an electronic device that is repeatedly bent, the exterior body gradually deteriorates with bending, or in some cases, a crack is likely to occur. Further, when the surface of the active material or the like comes into contact with the electrolytic solution along with charge / discharge, a decomposition reaction of the electrolytic solution occurs, and gas or the like may be generated. When the exterior body expands due to gas generation, the exterior body may be easily broken along with the bending. By using one embodiment of the present invention, decomposition of the electrolytic solution can be suppressed; thus, for example, gas generation associated with charging and discharging may be suppressed. As a result, expansion and deformation of the exterior body and damage to the exterior body can be suppressed, which is preferable because the load on the exterior body is reduced.

Hereinafter, other components of the power storage device of one embodiment of the present invention will be described in detail. Note that when a flexible material is selected from the materials of the members described in this embodiment and used, a flexible power storage device can be manufactured.

≪Current collector≫
Examples of the positive electrode current collector 501 and the negative electrode current collector 504 include metals such as stainless steel, gold, platinum, zinc, iron, nickel, copper, aluminum, titanium, tantalum, and manganese, alloys thereof, or sintered carbon. Etc. can be used respectively. Alternatively, copper or stainless steel may be coated with carbon, nickel, titanium, or the like. Alternatively, an aluminum alloy to which an element that improves heat resistance, such as silicon, titanium, neodymium, scandium, or molybdenum, is added can be used. Alternatively, the current collector may be formed using a metal element that forms silicide by reacting with silicon. Examples of metal elements that react with silicon to form silicide include zirconium, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, and the like.

An irreversible reaction with the electrolytic solution 508 may occur on the surface of the positive electrode current collector 501 or the surface of the negative electrode current collector 504. Therefore, it is preferable that the positive electrode current collector 501 and the negative electrode current collector 504 have low reactivity with the electrolytic solution 508. For example, it is preferable to use stainless steel or the like for the positive electrode current collector 501 or the negative electrode current collector 504 because the reactivity with the electrolytic solution 508 can be further lowered.

The positive electrode current collector 501 and the negative electrode current collector 504 include a foil shape, a plate shape (sheet shape), a net shape, a columnar shape, a coil shape, a punching metal shape, an expanded metal shape, a porous shape, and a nonwoven fabric, respectively. Various shapes including the above can be used as appropriate. Furthermore, in order to increase the adhesion with the active material layer, each of the positive electrode current collector 501 and the negative electrode current collector 504 may have fine unevenness on the surface. The positive electrode current collector 501 and the negative electrode current collector 504 may each have a thickness of 5 μm to 30 μm.

Moreover, you may provide an undercoat layer in a part of surface of an electrical power collector. Here, the undercoat layer refers to the purpose of reducing the interface resistance between the active material layer and the current collector and the adhesion between the active material layer and the current collector before applying the paste on the current collector. A film formed on the current collector for the purpose. Note that the undercoat layer may not be formed on the entire surface of the current collector, and may be formed (partially) in an island shape. Further, the undercoat layer may express a capacity as an active material. For example, a carbon material can be used as the undercoat layer. Examples of the carbon material that can be used include graphite, carbon black such as acetylene black and ketjen black, and carbon nanotubes.

≪Active material layer≫
The positive electrode active material layer 502 includes one or more types of positive electrode active materials. The negative electrode active material layer 505 includes one or more types of negative electrode active materials.

The positive electrode active material and the negative electrode active material play a central role in the battery reaction of the power storage device and release and absorb carrier ions. In order to increase the life of the power storage device, the active material is preferably a material having a small capacity related to the irreversible reaction of the battery reaction, and preferably a material having high charge / discharge efficiency.

As the positive electrode active material, a material that can insert and desorb carrier ions such as lithium ions can be used. Examples of the positive electrode active material include materials having an olivine type crystal structure, a layered rock salt type crystal structure, a spinel type crystal structure, and a NASICON type crystal structure.

For example, a compound such as LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , V ₂ O ₅ , Cr ₂ O ₅ , or MnO ₂ can be used as the positive electrode active material.

As a material having an olivine type crystal structure, a lithium-containing composite phosphate (general formula LiMPO ₄ (M is one or more of Fe (II), Mn (II), Co (II), Ni (II))) Is mentioned. Representative examples of the general formula LiMPO ₄ include LiFePO ₄ , LiNiPO ₄ , LiCoPO ₄ , LiMnPO ₄ , LiFe _a Ni _b PO ₄ , LiFe _a Co _b PO ₄ , LiFe _a Mn _b PO ₄ , LiNi _a Co _b PO ₄ . 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 M _e PO ₄ , LiNi _c Co _d Mn _e PO ₄ (c + d + e ≦ _{1, 0 <c <1,0 <d} <1,0 <e <1), LiFe f Ni g Co h Mn i PO 4 (f + g + h + i is 1 or less, 0 <f <1,0 < and compounds such as g <1, 0 <h <1, 0 <i <1).

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

By using LiFePO ₄ as the positive electrode active material, it is possible to realize a power storage device that is stable and highly safe against an external load such as overcharge. Therefore, it is particularly excellent as a power storage device used for mobile devices that are carried around, wearable devices that are worn on the body, and the like.

Examples of the material having a layered rock salt type crystal structure include NiCo-based materials (general formulas such as lithium cobaltate (LiCoO ₂ ), LiNiO ₂ , LiMnO ₂ , Li ₂ MnO ₃ , LiNi _0.8 Co _0.2 O _2). Is a NiMn system such as LiNi _x Co _1-x O ₂ (0 <x <1), LiNi _0.5 Mn _0.5 O ₂ (general formula is LiNi _x Mn _1-x O ₂ (0 <x _{<1)), LiNi 1/3 Mn} 1/3 Co 1/3 O 2 , etc. NiMnCo system (also referred to as NMC. general _{formula, LiNi x Mn y Co 1-} x-y O 2 (x> 0, y > 0, x + y <1)). _{Moreover, Li (Ni 0.8 Co 0.15 Al} 0.05) O 2, Li 2 MnO 3 -LiMO 2 (M is Co, Ni or Mn) may also be mentioned, and the like.

Particularly, LiCoO ₂ has the capacity is large, it is stable in the atmosphere as compared to LiNiO _2, because there are advantages such that it is thermally stable than LiNiO _2, preferred.

Examples of the material having a spinel crystal structure include LiMn ₂ O ₄ , Li _{1 + x} Mn _2−x O ₄ , Li (MnAl) ₂ O ₄ , LiMn _1.5 Ni _0.5 O _{4, and the} like.

When a small amount of lithium nickelate (LiNiO ₂ or LiNi _1-x MO ₂ (M = Co, Al, etc.)) is mixed with a material having a spinel type crystal structure containing manganese such as LiMn ₂ O ₄ , elution of manganese This is preferable because there are advantages such as suppressing the decomposition of the electrolytic solution.

Alternatively, as a positive electrode active material, a general formula Li _(2-j) MSiO ₄ (M is one or more of Fe (II), Mn (II), Co (II), Ni (II), 0 ≦ j ≦ 2) Lithium-containing composite silicates such as can be used. Representative examples of the general formula Li _(2-j) MSiO ₄ include Li _(2-j) FeSiO ₄ , Li _(2-j) NiSiO ₄ , Li _(2-j) CoSiO ₄ , Li _(2-j) MnSiO _{4, Li (2-j)} Fe k Ni l SiO 4, Li (2-j) Fe k Co l SiO 4, Li (2-j) Fe k Mn l SiO 4, Li (2-j) Ni k Co _{l SiO 4, Li (2-} j) Ni k Mn l SiO 4 (k + l is 1 or _{less, 0 <k <1,0 <l} <1), Li (2-j) Fe m Ni n Co q SiO 4, _{Li (2-j) Fe m} Ni n Mn q SiO 4, Li (2-j) Ni m Co n Mn q SiO 4 (m + n + q is 1 or less, 0 <m <1,0 <n <1,0 <q _{<1), Li (2-} j) Fe r Ni s Co t Mn _Examples include _u SiO ₄ (r + s + t + u is 1 or less, 0 <r <1, 0 <s <1, 0 <t <1, 0 <u <1).

Alternatively, as a positive electrode active material, A _x M ₂ (XO ₄ ) ₃ (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb, Al, X = S, P, Mo, W, As , Si), a NASICON type compound represented by the general formula can be used. Examples of the NASICON type compound include Fe ₂ (MnO ₄ ) ₃ , Fe ₂ (SO ₄ ) ₃ , and Li ₃ Fe ₂ (PO ₄ ) ₃ .

Alternatively, as a positive electrode active material, a compound represented by a general formula of Li ₂ MPO ₄ F, Li ₂ MP ₂ O ₇ , Li ₅ MO ₄ (M = Fe, Mn), a perovskite type fluoride such as NaF ₃ or FeF _{3 is used.} , Metal chalcogenides such as TiS ₂ and MoS ₂ (sulfides, selenides, tellurides), materials having an inverse spinel crystal structure such as LiMVO ₄ , vanadium oxides (V ₂ O ₅ , V ₆ O ₁₃ , LiV ₃ O _{8 and the} like), manganese oxide, organic sulfur compounds, and the like can be used.

A material obtained by combining a plurality of the above materials may be used as the positive electrode active material. For example, a solid solution obtained by combining a plurality of the above materials can be used as the positive electrode active material. For example, a solid solution of LiCo _1/3 Mn _1/3 Ni _1/3 O ₂ and Li ₂ MnO ₃ can be used as the positive electrode active material.

When the carrier ion is an alkali metal ion other than lithium ion or alkaline earth metal ion, as the positive electrode active material, in the lithium compound, lithium-containing composite phosphate, and lithium-containing composite silicate, lithium is used. A compound substituted with a carrier such as an alkali metal (for example, sodium or potassium) or an alkaline earth metal (for example, calcium, strontium, barium, beryllium, magnesium) may be used.

The average particle diameter of the primary particles of the positive electrode active material is preferably, for example, 5 nm or more and 100 μm or less.

For example, when a lithium-containing composite phosphate having an olivine structure is used as the positive electrode active material, lithium diffusion is slow because the lithium diffusion path is one-dimensional. Therefore, when the lithium-containing composite phosphate having an olivine structure is used, the average particle diameter of the positive electrode active material is preferably 5 nm or more and 1 μm or less, for example, in order to increase the charge / discharge rate. Alternatively, the specific surface area of the positive electrode active material is preferably 10 m ² / g or more and 50 m ² / g or less, for example.

In the active material having an olivine structure, for example, an active material having a layered rock salt type crystal structure has very little structural change due to charge / discharge, and the crystal structure is stable. Is stable, and a highly safe power storage device can be realized when used as a positive electrode active material.

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

Examples of the carbon-based material include graphite, graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotube, graphene, and carbon black. Examples of graphite include artificial graphite such as mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch-based artificial graphite, and natural graphite such as spheroidized natural graphite. In addition, the shape of graphite includes a scale-like shape and a spherical shape.

Graphite shows a base potential as low as lithium metal when lithium ions are inserted into the graphite (when a lithium-graphite intercalation compound is produced) (0.1 to 0.3 V vs. Li ^/ Li ⁺ ). Thereby, a lithium ion secondary battery can show a high operating voltage. Further, graphite is preferable because it has advantages such as relatively high capacity per unit volume, small volume expansion, low cost, and high safety compared to lithium metal.

When the carrier ions are lithium ions, examples of alloy materials include Mg, Ca, Ga, Si, Al, Ge, Sn, Pb, As, Sb, Bi, Ag, Au, Zn, Cd, Hg, and In. A material containing at least one of the above can be used. Such an element has a larger capacity than carbon, and silicon is particularly preferable because its theoretical capacity is 4200 mAh / g. Examples of alloy materials (compound materials) using such elements include Mg ₂ Si, Mg ₂ Ge, Mg ₂ Sn, SnS ₂ , V ₂ Sn ₃ , FeSn ₂ , CoSn ₂ , and Ni ₃ Sn _2. Cu ₆ Sn ₅ , Ag ₃ Sn, Ag ₃ Sb, Ni ₂ MnSb, CeSb ₃ , LaSn ₃ , La ₃ Co ₂ Sn ₇ , CoSb ₃ , InSb, and SbSn.

Further, as the negative electrode active material, SiO, SnO, SnO _2, titanium dioxide _(TiO 2), lithium titanium oxide _{(Li 4 Ti 5 O 12)} , lithium - graphite intercalation _{compounds, (Li x C 6),} niobium pentoxide An oxide such as (Nb ₂ O ₅ ), tungsten oxide (WO ₂ ), or molybdenum oxide (MoO ₂ ) can be used.

Further, as the anode active material, a double nitride of lithium and a transition metal, _{Li 3-x M x} N with Li ₃ N type structure (M is Co, Ni or Cu) 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 lithium and transition metal double nitride is used, since the negative electrode active material contains lithium ions, it can be combined with a material such as V ₂ O ₅ or Cr ₃ O ₈ that does not contain lithium ions as the positive electrode active material. Note that even when a material containing lithium ions is used for the positive electrode active material, lithium and transition metal double nitride can be used as the negative electrode active material by previously desorbing lithium ions contained in the positive electrode active material.

A material that causes a conversion reaction can also be used as the negative electrode active material. For example, a transition metal oxide that does not undergo an alloying reaction with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), or iron oxide (FeO), may be used as the negative electrode active material. As a material causing the conversion reaction, oxides such as Fe ₂ O ₃ , CuO, Cu ₂ O, RuO ₂ and Cr ₂ O ₃ , sulfides such as CoS _0.89 , NiS and CuS, Zn ₃ N _{2 are further included.} And nitrides such as Cu ₃ N and Ge ₃ N ₄ , phosphides such as NiP ₂ , FeP ₂ and CoP ₃ , and fluorides such as FeF ₃ and BiF ₃ .

The average particle diameter of the primary particles of the negative electrode active material is preferably, for example, from 5 nm to 100 μm.

Each of the positive electrode active material layer 502 and the negative electrode active material layer 505 preferably includes a binder.

As the binder, for example, a water-soluble polymer is preferably included. For example, polysaccharides can be used as the water-soluble polymer. As the polysaccharide, cellulose derivatives such as carboxymethyl cellulose (CMC), methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, regenerated cellulose, starch, and the like can be used.

As the binder, it is preferable to use a rubber material such as styrene-butadiene rubber (SBR), styrene / isoprene / styrene rubber, acrylonitrile / butadiene rubber, butadiene rubber, fluororubber, ethylene / propylene / diene copolymer. These rubber materials are more preferably used in combination with the water-soluble polymer described above.

Or as binder, polystyrene, polymethyl acrylate, polymethyl methacrylate (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), polyethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, polytetrafluoro Use materials such as ethylene, polyethylene, polypropylene, isobutylene, polyethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyvinyl chloride, ethylene propylene diene polymer, polyvinyl acetate, polymethyl methacrylate, and nitrocellulose. Is preferred.

You may use a binder in combination of 2 or more types among the above.

The content of the binder with respect to the total amount of the active material layer is preferably 1 wt% or more and 10 wt% or less, more preferably 2 wt% or more and 8 wt% or less, and further preferably 3 wt% or more and 5 wt% or less.

Each of the positive electrode active material layer 502 and the negative electrode active material layer 505 may include a conductive additive.

As the conductive assistant, for example, a carbon material, a metal material, or a conductive ceramic material can be used. Moreover, you may use a fibrous material as a conductive support agent. The content of the conductive additive relative 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 assistant can form an electrically conductive network in the electrode. The conductive auxiliary agent can maintain the electric conduction path between the negative electrode active materials. By adding a conductive additive in the active material layer, an active material layer having high electrical conductivity can be realized.

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

Flaky graphene has excellent electrical properties such as high electrical conductivity, and excellent physical properties such as flexibility and mechanical strength. Therefore, by using graphene as a conductive additive, the contact point and the contact area between the active materials can be increased.

Note that in this specification, graphene includes single-layer graphene or multilayer graphene of two to 100 layers. Single-layer graphene refers to a sheet of one atomic layer of carbon molecules having a π bond. The graphene oxide refers to a compound obtained by oxidizing the graphene. Note that in the case of reducing graphene oxide to form graphene, all oxygen contained in the graphene oxide is not desorbed and part of oxygen remains in the graphene. In the case where oxygen is contained in graphene, the proportion of oxygen is 2 atomic% or more and 11 atomic% or less, preferably 3 atomic% or more and 10 atomic% or less of the entire graphene as measured by XPS.

Graphene enables surface contact with low contact resistance, and is extremely conductive even if it is thin, and a conductive path can be efficiently formed in an active material layer even with a small amount.

When an active material having a small average particle diameter, for example, an active material having a size of 1 μm or less is used, the specific surface area of the active material is large, and more conductive paths are required to connect the active materials. In such a case, it is particularly preferable to use graphene that has very high conductivity and can efficiently form a conductive path even in a small amount.

Below, the cross-sectional structural example in the case of using a graphene as a conductive support agent for a positive electrode active material layer is demonstrated. Note that graphene may be used for the negative electrode active material layer as a conductive additive.

FIG. 9 is a longitudinal sectional view of the positive electrode active material layer 502. The positive electrode active material layer 502 includes a granular positive electrode active material 522, graphene 521 as a conductive additive, and a binder (also referred to as a binder, not shown).

In the vertical cross section of the positive electrode active material layer 502, as shown in FIG. 9, the sheet-like graphene 521 is dispersed substantially uniformly inside the positive electrode active material layer 502. In FIG. 9, the graphene 521 is schematically represented by a thick line, but is actually a thin film having a single-layer or multi-layer thickness of carbon molecules. Since the plurality of graphenes 521 are formed so as to enclose or cover the plurality of granular positive electrode active materials 522, or are attached to the surfaces of the plurality of granular positive electrode active materials 522, they are in surface contact with each other. . Further, the graphenes 521 are in surface contact with each other, so that a plurality of graphenes 521 form a three-dimensional electrical conduction network.

This is because graphene oxide having extremely high dispersibility in a polar solvent is used for forming the graphene 521. In order to volatilize and remove the solvent from the dispersion medium containing the uniformly dispersed graphene oxide and reduce the graphene oxide into graphene, the graphene 521 remaining in the positive electrode active material layer 502 partially overlaps and is in surface contact with each other. The electric conduction path is formed by being dispersed. Note that the reduction of graphene oxide may be performed by, for example, heat treatment or may be performed using a reducing agent.

Therefore, unlike the granular conductive auxiliary agent such as acetylene black that makes point contact with the active material, the graphene 521 enables surface contact with low contact resistance, so that the granular amount can be increased without increasing the amount of the conductive auxiliary agent. The electrical conductivity between the positive electrode active material 522 and the graphene 521 can be improved. Therefore, the ratio of the positive electrode active material 522 in the positive electrode active material layer 502 can be increased. Thereby, the discharge capacity of the power storage device can be increased.

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

The electrode used for the power storage device of one embodiment of the present invention can be manufactured by a variety of methods. For example, when an active material layer is formed on a current collector using a coating method, a paste is prepared by mixing an active material, a binder, a conductive additive, and a dispersion medium (also referred to as a solvent). The paste may be applied to vaporize the dispersion medium. Thereafter, if necessary, pressing may be performed by a compression method such as a roll press method or a flat plate press method, and consolidation may be performed.

As the dispersion medium, for example, water or an organic solvent having polarity such as N-methylpyrrolidone (NMP) or dimethylformamide can be used. From the viewpoint of safety and cost, it is preferable to use water.

≪Separator≫
For the separator 507, paper, nonwoven fabric, glass fiber, ceramics, or synthetic fiber such as nylon (polyamide), vinylon (polyvinyl alcohol fiber), polyester, acrylic, polyolefin, polyurethane, or the like can be used. The separator 507 may have a single layer structure or a laminated structure.

More specifically, the separator 507 includes, for example, a fluoropolymer, a polyether such as polyethylene oxide and polypropylene oxide, a polyolefin such as polyethylene and polypropylene, polyacrylonitrile, polyvinylidene chloride, polymethyl methacrylate, polymethyl acrylate, and polyvinyl. One or two kinds selected from alcohol, polymethacrylonitrile, polyvinyl acetate, polyvinylpyrrolidone, polyethyleneimine, polybutadiene, polystyrene, polyisoprene, polyurethane polymers and derivatives thereof, cellulose, paper, nonwoven fabric, and glass fiber. A combination of more than one species can be used.

≪Exterior body≫
It is preferable that the exterior body 509 does not cause a significant reaction with the electrolytic solution 508 on the surface in contact with the electrolytic solution 508, that is, the inner surface. In addition, when moisture enters the battery cell 500 from the outside of the battery cell 500, a reaction between the components of the electrolytic solution 508 and water may occur. Therefore, the exterior body 509 preferably has low moisture permeability.

The exterior body 509 is provided with a metal thin film having excellent flexibility such as aluminum, stainless steel, copper, nickel on a film using, for example, polyethylene, polypropylene, polycarbonate, ionomer, polyamide, etc. A film having a three-layer structure provided with an insulating synthetic resin film such as a polyamide-based resin or a polyester-based resin can be used as the outer surface of the outer package. By setting it as such a three-layer structure, while permeating | transmitting electrolyte solution and gas, the insulation is ensured and it has electrolyte solution resistance collectively. The exterior body is folded inward and overlapped, or the inner surfaces of the two exterior bodies are overlapped face to face, and heat is applied, so that the material on the inner surface melts and the two exterior bodies can be fused and sealed. A structure can be made.

Assuming that the part where the outer package is fused and the sealing structure is formed is a sealing part, when the outer package is folded inward and overlapped, the sealing part is formed at a place other than the crease. The first region and the second region overlapping the first region are fused together. Moreover, when two exterior bodies are stacked, a sealing portion is formed on the entire outer periphery by a method such as heat sealing.

The battery cell 500 can have a flexible structure by using the flexible exterior body 509. If it is set as the structure which has flexibility, it can mount in the electronic device which has at least one part which has flexibility, and the battery cell 500 can also be bent according to a deformation | transformation of an electronic device.

As described above, the power storage device of this embodiment has high safety because a non-aqueous solvent that exhibits flame retardancy is used as an electrolyte. In addition, the power storage device of this embodiment uses a non-aqueous solvent that is difficult to be decomposed as an electrolytic solution, and thus has good cycle characteristics and high reliability.

This embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 2)
In this embodiment, various modes of the power storage device of one embodiment of the present invention will be described with reference to FIGS. Note that the power storage device of one embodiment of the present invention is not limited to the structure exemplified in this embodiment, and various shapes and forms can be applied.

Note that Embodiment 1 can be referred to for materials that can be used for the positive electrode, the negative electrode, the separator, the electrolytic solution, and the like included in each power storage device illustrated in this embodiment.

[Storage battery using wound body]
10 and 11 illustrate a configuration example of a storage battery using a wound body, which is the power storage device of one embodiment of the present invention.

A wound body 993 illustrated in FIGS. 10A and 10B includes a negative electrode 994, a positive electrode 995, and a separator 996.

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

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

Here, the area of the negative electrode 994 that does not overlap with the positive electrode 995 is preferably as small as possible. FIG. 10B illustrates an example in which the width 1091 of the negative electrode 994 is smaller than the width 1092 of the positive electrode 995. Further, the end portion of the negative electrode 994 is located inside the positive electrode 995. With such a structure, the negative electrode 994 can be entirely overlapped with the positive electrode 995, or the area of the negative electrode 994 that does not overlap with the positive electrode 995 can be reduced.

Moreover, when the area of the positive electrode 995 is too large with respect to the area of the negative electrode 994, the surplus part of the positive electrode 995 increases, and for example, the capacity of the storage battery per volume decreases. Therefore, for example, it is preferable that the end portion of the negative electrode 994 be positioned inside the end portion of the positive electrode 995. The distance between the end of the positive electrode 995 and the end of the negative electrode 994 is preferably 3 mm or less, more preferably 0.5 mm or less, and even more preferably 0.1 mm or less. Alternatively, the difference in width between the positive electrode 995 and the negative electrode 994 is preferably 6 mm or less, more preferably 1 mm or less, and further preferably 0.2 mm or less. Alternatively, it is preferable that the width 1091 and the width 1092 have substantially the same value, and the end portion of the negative electrode 994 is approximately aligned with the end portion of the positive electrode 995.

A storage battery 980 illustrated in FIG. 11B includes a film 981, a film 982 having a recess, and a wound body 993, as illustrated in FIG. The storage battery 990 is obtained by storing a wound body 993 in a space formed by bonding a film 981 and a film 982 serving as exterior bodies together by thermocompression bonding or the like. The wound body 993 has a terminal 997 and a terminal 998, and is impregnated with an electrolytic solution inside the film 981 and the film 982.

For the film 981 and the film 982, for example, a metal material such as aluminum or a resin material can be used. When a resin material is used as a material for the film 981 and the film 982, the film 981 and the film 982 can be deformed when a force is applied from the outside, and a flexible storage battery can be manufactured.

Although FIGS. 11A and 11B show an example in which two films are used, a space is formed by folding one film, and the above-described wound body 993 is accommodated in the space. Good.

By using a resin material or the like for the exterior body or the sealing container, the entire power storage device can be flexible. However, in the case where a resin material is used for the exterior body or the sealing container, a portion to be connected to the outside is a conductive material.

A storage battery 990 illustrated in FIG. 12B includes an exterior body 991, an exterior body 992, and a wound body 993, as illustrated in FIG.

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

[Cylindrical storage battery]
Next, a cylindrical storage battery is shown as an example of a storage battery using a wound body.

A cylindrical storage battery 600 shown in FIG. 13A has a positive electrode cap (battery cover) 601 on the top surface and a battery can (outer can) 602 on the side surface and bottom surface. The positive electrode cap and the battery can (outer can) 602 are insulated by a gasket (insulating packing) 610.

FIG. 13B is a schematic cross-sectional view of a cylindrical storage battery. Inside the hollow cylindrical battery can 602, a battery element in which a strip-like positive electrode 604 and a strip-like negative electrode 606 are wound with a separator 605 interposed therebetween is provided. Although not shown, the battery element is wound around a center pin. The battery can 602 has one end closed and the other end open. For the battery can 602, a metal such as aluminum or titanium that is corrosion resistant to the electrolytic solution, an alloy thereof, or an alloy of these with another metal (for example, stainless steel) can be used. Moreover, in order to prevent the corrosion by electrolyte solution, it is preferable to coat | cover aluminum etc. 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 electrolyte (not shown) is injected into the inside of the battery can 602 provided with the battery element.

Since the positive electrode and the negative electrode used for the cylindrical storage battery are wound, it is preferable to form an active material on both surfaces 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. Both the positive electrode terminal 603 and the negative electrode terminal 607 can use a metal material such as aluminum. The positive terminal 603 is resistance-welded to the safety valve mechanism 612 and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC (Positive Temperature Coefficient) element 611. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the increase in the internal pressure of the battery exceeds a predetermined threshold value. The PTC element 611 is a heat-sensitive resistance element that increases in resistance when the temperature rises, and prevents abnormal heat generation by limiting the amount of current by increasing the resistance. For the PTC element, barium titanate (BaTiO ₃ ) -based semiconductor ceramics or the like can be used.

Here, the area of the negative electrode 606 that does not overlap with the positive electrode 604 is preferably as small as possible. For example, the end portion of the negative electrode 994 is preferably positioned on the inner side than the end portion of the positive electrode 995. The distance between the end of the positive electrode 604 and the end of the negative electrode 606 is preferably 3 mm or less, more preferably 0.5 mm or less, and even more preferably 0.1 mm or less. Alternatively, the difference between the width 1093 of the positive electrode 604 and the width 1094 of the negative electrode 606 is preferably 6 mm or less, more preferably 1 mm or less, and further preferably 0.2 mm or less. Alternatively, it is preferable that the width 1093 and the width 1094 have substantially the same value, and the end portion of the negative electrode 606 is approximately aligned with the end portion of the positive electrode 604.

[Coin-type storage battery]
FIG. 14 illustrates an example of a coin-type storage battery which is a power storage device of one embodiment of the present invention. 14A is an external view of a coin-type (single-layer flat type) storage battery, and FIGS. 14B and 14C are examples of cross-sectional views thereof.

In the coin-type storage battery 300, a positive electrode can 301 also serving as a positive electrode terminal and a negative electrode can 302 also serving as a negative electrode terminal are insulated and sealed with a gasket 303 formed of polypropylene or the like.

The positive electrode 304 includes a positive electrode current collector 305 and a positive electrode active material layer 306 in contact with each other. The negative electrode 307 includes a negative electrode current collector 308 and a negative electrode active material layer 309 that are in contact with each other. Note that each of the positive electrode and the negative electrode used for the coin-type storage battery only needs to have an active material layer on one side.

In addition to the positive electrode active material, the positive electrode active material layer 306 may include a binder for increasing the adhesion of the positive electrode active material, a conductive additive for increasing the conductivity of the positive electrode active material layer, and the like. In addition to the negative electrode active material, the negative electrode active material layer 309 may include a binder for increasing the adhesion of the negative electrode active material, a conductive additive for increasing the conductivity of the negative electrode active material layer, and the like.

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

Here, the shapes and areas of the positive electrode 304 and the negative electrode 307 are preferably substantially the same, and the end portion of the positive electrode 304 and the end portion of the negative electrode 307 are preferably substantially aligned. FIG. 14B illustrates an example in which the end portion of the positive electrode 304 and the end portion of the negative electrode 307 are aligned.

Alternatively, the area of the negative electrode 307 is preferably larger than the area of the positive electrode 304, and the end portion of the positive electrode 304 is preferably located on the inner side than the end portion of the negative electrode 307. FIG. 14C illustrates an example in which the end portion of the positive electrode 304 is positioned inside the end portion of the negative electrode 307.

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

The negative electrode 307, the positive electrode 304, and the separator 310 are impregnated in the electrolyte, and the positive electrode 304, the separator 310, the negative electrode 307, and the negative electrode can 302 are placed with the positive electrode can 301 facing down, as shown in FIGS. 14B and 14C. The coin-shaped storage battery 300 is manufactured by laminating in order and pressing the positive electrode can 301 and the negative electrode can 302 through the gasket 303.

[Power storage system]
Next, structural examples of the power storage system will be described with reference to FIGS. Here, the power storage system refers to, for example, a device equipped with a power storage device. The power storage system described in this embodiment includes the power storage device of one embodiment of the present invention.

15A and 15B are external views of a power storage system. The power storage system includes a circuit board 900 and a storage battery 913. A label 910 is attached to the storage battery 913. Further, as illustrated in FIG. 15B, the power storage system includes a terminal 951 and a terminal 952, and an antenna 914 and an antenna 915 on the back of the label 910.

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

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

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

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

Note that the structure of the power storage system is not limited to FIG. A modification is shown below. Note that the above description can be incorporated as appropriate for the same portions as those of the power storage system illustrated in FIGS.

For example, as shown to FIG. 16 (A-1) and (A-2), you may provide an antenna in each of a pair of surface which opposes among the storage batteries 913 shown to FIG. 15 (A) and (B). . 16A-1 is an external view seen from one surface side of the pair of surfaces, and FIG. 16A-2 is an external view seen from the other surface side of the pair of surfaces. is there.

As shown in FIG. 16A-1, an antenna 914 is provided on one of a pair of surfaces of the storage battery 913 with a layer 916 sandwiched therebetween, and as shown in FIG. 16A-2, a pair of surfaces of the storage battery 913 is provided. An antenna 915 is provided with the layer 917 interposed therebetween. The layer 917 has a function of shielding an 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 size of both the antenna 914 and the antenna 915 can be increased.

Alternatively, as shown in FIGS. 16B-1 and B-2, another antenna is provided on each of a pair of opposed surfaces of the storage battery 913 shown in FIGS. 15A and 15B. Also good. 16B-1 is an external view seen from one surface side of the pair of surfaces, and FIG. 16B-2 is an external view seen from the other surface side of the pair of surfaces. is there.

As shown in FIG. 16B-1, an antenna 914 and an antenna 915 are provided on one of a pair of surfaces of the storage battery 913 with the layer 916 interposed therebetween, and as shown in FIG. An antenna 918 is provided with the layer 917 interposed between the other of the pair of surfaces. The antenna 918 has a function of performing data communication with an external device, for example. For the antenna 918, for example, an antenna having a shape applicable to the antenna 914 and the antenna 915 can be used. As a communication method between the power storage system and the other devices via the antenna 918, a response method that can be used between the power storage system and the other devices such as NFC can be applied.

Alternatively, as illustrated in FIG. 17A, a display device 920 may be provided in the storage battery 913 illustrated in FIGS. The display device 920 is electrically connected to the terminal 911 through the terminal 919. Note that the label 910 is not necessarily provided in a portion where the display device 920 is provided.

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

Alternatively, as shown in FIG. 17B, a sensor 921 may be provided in the storage battery 913 shown in FIGS. 15A and 15B. The sensor 921 is electrically connected to the terminal 911 through the terminal 922. Note that the sensor 921 may be provided on the back side of the label 910.

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

The power storage device of one embodiment of the present invention is used for the storage battery and the power storage system described in this embodiment. In the power storage device of one embodiment of the present invention, the electrolytic solution is unlikely to be decomposed, so that a reduction in capacity due to a charge / discharge cycle of the storage battery or the power storage system can be suppressed. Further, the safety and reliability of the storage battery and the power storage system can be improved.

This embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 3)
In this embodiment, a battery control unit (BMU) that can be used in combination with the power storage device of one embodiment of the present invention and a transistor suitable for a circuit included in the battery control unit are described in FIGS. This will be described with reference to FIG. In the present embodiment, a battery control unit that is particularly suitable for use in combination with battery cells connected in series will be described.

When charging / discharging is repeated for a plurality of battery cells connected in series, the capacity (output voltage) varies depending on variations in characteristics between the battery cells. In battery cells connected in series, the capacity at the time of overall discharge depends on the battery cells having a small capacity. If the capacity varies, the capacity at the time of discharge decreases. In addition, if charging is performed with reference to a battery cell having a small capacity, there is a risk of insufficient charging. Further, if charging is performed with reference to a battery cell having a large capacity, there is a risk of overcharging.

Therefore, the battery control unit of the power storage device having the battery cells connected in series has a function of aligning the variation in capacity between the battery cells that causes insufficient charging or overcharging. The circuit configuration for aligning the variation in capacity between battery cells includes a resistance method, a capacitor method, or an inductor method, but here is an example of a circuit configuration that can use a transistor with a small off-current to equalize the variation in capacity. Will be described.

As the transistor with low off-state current, a transistor including an oxide semiconductor (OS transistor) in a channel formation region is preferable. By using an OS transistor with a small off-state current in the circuit configuration of the battery control unit of the power storage device, the amount of charge leaking from the battery can be reduced, and a decrease in capacity over time can be suppressed.

As the oxide semiconductor used for the channel formation region, an In-M-Zn oxide (M is Ga, Sn, Y, Zr, La, Ce, or Nd) is used. In the target used for forming the oxide semiconductor film, when the atomic ratio of metal elements is In: M: Zn = x ₁ : y ₁ : z _{1 ,} x ₁ / y ₁ is 1/3 or more 6 Hereinafter, it is further 1 or more and 6 or less, and z ₁ / y ₁ is preferably 1/3 or more and 6 or less, and more preferably 1 or more and 6 or less. Note that when z ₁ / y ₁ is greater than or equal to 1 and less than or equal to 6, a CAAC-OS film can be easily formed as the oxide semiconductor film.

Here, the CAAC-OS film is described.

The CAAC-OS film is one of oxide semiconductor films having a plurality of c-axis aligned crystal parts.

A plurality of crystal parts are confirmed by observing a bright field image of a CAAC-OS film and a combined analysis image (also referred to as a high-resolution TEM image) of a CAAC-OS film with a transmission electron microscope (TEM: Transmission Electron Microscope). Can do. On the other hand, a clear boundary between crystal parts, that is, a crystal grain boundary (also referred to as a grain boundary) cannot be confirmed even by a high-resolution TEM image. Therefore, it can be said that the CAAC-OS film is unlikely to decrease in electron mobility due to crystal grain boundaries.

When a high-resolution TEM image of a cross section of the CAAC-OS film is observed from a direction substantially parallel to the sample surface, it can be confirmed that metal atoms are arranged in layers in the crystal part. Each layer of metal atoms has a shape reflecting a surface (also referred to as a formation surface) on which a CAAC-OS film is formed or unevenness on the upper surface, and is arranged in parallel with the formation surface or upper surface of the CAAC-OS film. .

On the other hand, when a high-resolution TEM image of the plane of the CAAC-OS film is observed from a direction substantially perpendicular to the sample surface, it can be confirmed that metal atoms are arranged in a triangular shape or a hexagonal shape in the crystal part. However, there is no regularity in the arrangement of metal atoms between different crystal parts.

When structural analysis is performed on a CAAC-OS film using an X-ray diffraction (XRD) apparatus, for example, in the analysis of a CAAC-OS film having an InGaZnO ₄ crystal by an out-of-plane method, A peak may appear when the diffraction angle (2θ) is around 31 °. Since this peak is attributed to the (009) plane of the InGaZnO ₄ crystal, the crystal of the CAAC-OS film has c-axis orientation, and the c-axis is oriented in a direction substantially perpendicular to the formation surface or the top surface. Can be confirmed.

Note that when the CAAC-OS film including an InGaZnO ₄ crystal is analyzed by an out-of-plane method, a peak may also appear when 2θ is around 36 ° in addition to the peak where 2θ is around 31 °. A peak at 2θ of around 36 ° indicates that a crystal having no c-axis alignment is included in part of the CAAC-OS film. The CAAC-OS film preferably has a peak at 2θ of around 31 ° and no peak at 2θ of around 36 °.

The CAAC-OS film is an oxide semiconductor film with a low impurity concentration. The impurity is an element other than the main component of the oxide semiconductor film, such as hydrogen, carbon, silicon, or a transition metal element. In particular, an element such as silicon, which has a stronger bonding force with oxygen than the metal element included in the oxide semiconductor film, disturbs the atomic arrangement of the oxide semiconductor film by depriving the oxide semiconductor film of oxygen, and has crystallinity. It becomes a factor to reduce. In addition, heavy metals such as iron and nickel, argon, carbon dioxide, and the like have large atomic radii (or molecular radii). Therefore, if they are contained inside an oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disturbed, and crystallinity is increased. It becomes a factor to reduce. Note that the impurity contained in the oxide semiconductor film might serve as a carrier trap or a carrier generation source.

The CAAC-OS film is an oxide semiconductor film with a low density of defect states. For example, oxygen vacancies in the oxide semiconductor film can serve as carrier traps or can generate carriers by capturing hydrogen.

A low impurity concentration and a low density of defect states (low oxygen vacancies) is called high purity intrinsic or substantially high purity intrinsic. A highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has few carrier generation sources, and thus can have a low carrier density. Therefore, a transistor including the oxide semiconductor film is unlikely to have electrical characteristics (also referred to as normally-on) in which the threshold voltage is negative. A highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has few carrier traps. Therefore, a transistor including the oxide semiconductor film has a small change in electrical characteristics and has high reliability. Note that the charge trapped in the carrier trap of the oxide semiconductor film takes a long time to be released, and may behave as if it were a fixed charge. Therefore, a transistor including an oxide semiconductor film with a high impurity concentration and a high density of defect states may have unstable electrical characteristics.

In addition, a transistor including a CAAC-OS film has little variation in electrical characteristics due to irradiation with visible light or ultraviolet light.

Note that an OS transistor has a larger band gap than a transistor having silicon in a channel formation region (Si transistor), and thus dielectric breakdown is less likely to occur when a high voltage is applied. When battery cells are connected in series, a voltage of several hundred volts is generated. However, the circuit configuration of the battery control unit of the power storage device applied to such a battery cell may be configured by the OS transistor described above. Is suitable.

FIG. 18 illustrates an example of a block diagram of a power storage device. A power storage device BT00 shown in FIG. 18 is connected in series with a terminal pair BT01, a terminal pair BT02, a switching control circuit BT03, a switching circuit BT04, a switching circuit BT05, a transformation control circuit BT06, and a transformation circuit BT07. A battery unit BT08 including a plurality of battery cells BT09.

18 includes a terminal pair BT01, a terminal pair BT02, a switching control circuit BT03, a switching circuit BT04, a switching circuit BT05, a transformation control circuit BT06, and a transformation circuit BT07. The part can be called a battery control unit.

The switching control circuit BT03 controls operations of the switching circuit BT04 and the switching circuit BT05. Specifically, the switching control circuit BT03 determines the battery cell (discharge battery cell group) to be discharged and the battery cell (charge battery cell group) to be charged based on the voltage measured for each battery cell BT09.

Further, the switching control circuit BT03 outputs a control signal S1 and a control signal S2 based on the determined discharge battery cell group and charge battery cell group. The control signal S1 is output to the switching circuit BT04. This control signal S1 is a signal for controlling the switching circuit BT04 so as to connect the terminal pair BT01 and the discharge battery cell group. The control signal S2 is output to the switching circuit BT05. This control signal S2 is a signal for controlling the switching circuit BT05 so as to connect the terminal pair BT02 and the rechargeable battery cell group.

In addition, the switching control circuit BT03 is based on the configuration of the switching circuit BT04, the switching circuit BT05, and the transformer circuit BT07 so that terminals of the same polarity are connected between the terminal pair BT02 and the rechargeable battery cell group. A control signal S1 and a control signal S2 are generated.

Details of the operation of the switching control circuit BT03 will be described.

First, the switching control circuit BT03 measures the voltage for each of the plurality of battery cells BT09. Then, the switching control circuit BT03, for example, sets the battery cell BT09 having a voltage equal to or higher than a predetermined threshold as a high voltage battery cell (high voltage cell) and the battery cell BT09 having a voltage lower than the predetermined threshold as a low voltage battery cell (low voltage). Voltage cell).

Various methods can be used for determining the high voltage cell and the low voltage cell. For example, the switching control circuit BT03 determines whether each battery cell BT09 is a high voltage cell or a low voltage cell with reference to the voltage of the battery cell BT09 having the highest voltage or the lowest voltage among the plurality of battery cells BT09. You may judge. In this case, the switching control circuit BT03 determines whether each battery cell BT09 is a high voltage cell or a low voltage cell by determining whether the voltage of each battery cell BT09 is equal to or higher than a predetermined ratio with respect to the reference voltage. Can be judged. Then, the switching control circuit BT03 determines the discharge battery cell group and the charge battery cell group based on the determination result.

In the plurality of battery cells BT09, a high voltage cell and a low voltage cell can be mixed in various states. For example, in the switching control circuit BT03, among the high voltage cells and the low voltage cells, the portion where the highest number of high voltage cells are connected in series is the discharge battery cell group. In addition, the switching control circuit BT03 sets a portion where the most low voltage cells are continuously connected in series as a rechargeable battery cell group. Further, the switching control circuit BT03 may preferentially select the battery cell BT09 close to overcharge or overdischarge as the discharge battery cell group or the charge battery cell group.

Here, an operation example of the switching control circuit BT03 in the present embodiment will be described with reference to FIG. FIG. 19 is a diagram for explaining an operation example of the switching control circuit BT03. For convenience of explanation, FIG. 19 illustrates an example in which four battery cells BT09 are connected in series.

First, in the example of FIG. 19A, when the voltages of the battery cells a to d are the voltages Va to Vd, a case where Va = Vb = Vc> Vd is shown. That is, three continuous high voltage cells a to c and one low voltage cell d are connected in series. In this case, the switching control circuit BT03 determines three consecutive high voltage cells a to c as a discharge battery cell group. In addition, the switching control circuit BT03 determines the low voltage cell d as a rechargeable battery cell group.

Next, the example of FIG. 19B shows a case where Vc >> Va = Vb >> Vd. That is, two continuous low voltage cells a and b, one high voltage cell c, and one low voltage cell d near overdischarge are connected in series. In this case, the switching control circuit BT03 determines the high voltage cell c as a discharge battery cell group. In addition, since the low voltage cell d is close to overdischarge, the switching control circuit BT03 preferentially determines the low voltage cell d as a charging battery cell group instead of the two consecutive low voltage cells a and b.

Finally, the example of FIG. 19C shows a case where Va> Vb = Vc = Vd. That is, one high voltage cell a and three consecutive low voltage cells b to d are connected in series. In this case, the switching control circuit BT03 determines the high voltage cell a as a discharge battery cell group. In addition, the switching control circuit BT03 determines three consecutive low voltage cells b to d as a rechargeable battery cell group.

The switching control circuit BT03 is a control signal in which information indicating the discharge battery cell group to which the switching circuit BT04 is connected is set based on the results determined as in the examples of FIGS. 19A to 19C. The control signal S2 in which information indicating S1 and the rechargeable battery cell group to which the switching circuit BT05 is connected is set is output to the switching circuit BT04 and the switching circuit BT05.

The switching circuit BT04 sets the connection destination of the terminal pair BT01 to the discharge battery cell group determined by the switching control circuit BT03 according to the control signal S1 output from the switching control circuit BT03.

The terminal pair BT01 is composed of a pair of terminals A1 and A2. The switching circuit BT04 connects either one of the terminals A1 and A2 to the positive terminal of the battery cell BT09 located on the most upstream side (high potential side) in the discharge battery cell group, and the other to the discharge battery cell group. The connection destination of the terminal pair BT01 is set by connecting to the negative electrode terminal of the battery cell BT09 located most downstream (low potential side). Note that the switching circuit BT04 can recognize the position of the discharge battery cell group using the information set in the control signal S1.

The switching circuit BT05 sets the connection destination of the terminal pair BT02 to the rechargeable battery cell group determined by the switching control circuit BT03 according to the control signal S2 output from the switching control circuit BT03.

The terminal pair BT02 is configured by a pair of terminals B1 and B2. The switching circuit BT05 connects either one of the terminals B1 and B2 to the positive terminal of the battery cell BT09 located on the most upstream side (high potential side) in the charging battery cell group, and the other to the charging battery cell group. The connection destination of the terminal pair BT02 is set by connecting to the negative electrode terminal of the battery cell BT09 located most downstream (low potential side). Note that the switching circuit BT05 can recognize the position of the rechargeable battery cell group using the information set in the control signal S2.

20 and 21 are circuit diagrams showing configuration examples of the switching circuit BT04 and the switching circuit BT05.

In FIG. 20, the switching circuit BT04 has a plurality of transistors BT10 and buses BT11 and BT12. The bus BT11 is connected to the terminal A1. The bus BT12 is connected to the terminal A2. One of the sources or drains of the plurality of transistors BT10 is connected to the buses BT11 and BT12 alternately every other one. The other of the sources or drains of the plurality of transistors BT10 is connected between two adjacent battery cells BT09.

Note that, among the plurality of transistors BT10, the other of the source and the drain of the transistor BT10 located at the uppermost stream is connected to the positive terminal of the battery cell BT09 located at the uppermost stream of the battery unit BT08. In addition, among the plurality of transistors BT10, the other of the source and the drain of the transistor BT10 located on the most downstream side is connected to the negative electrode terminal of the battery cell BT09 located on the most downstream side of the battery unit BT08.

The switching circuit BT04 is one of the plurality of transistors BT10 connected to the bus BT11 and one of the plurality of transistors BT10 connected to the bus BT12 according to the control signal S1 applied to the gates of the plurality of transistors BT10. The discharge battery cell group and the terminal pair BT01 are connected to each other by bringing them into a conductive state. Thereby, the positive electrode terminal of battery cell BT09 located in the most upstream in the discharge battery cell group is connected with either one of terminal A1 or A2 of a terminal pair. Moreover, the negative electrode terminal of battery cell BT09 located in the most downstream in the discharge battery cell group is connected to either the terminal A1 or A2 of the terminal pair, that is, the terminal not connected to the positive electrode terminal.

An OS transistor is preferably used as the transistor BT10. Since the OS transistor has a small off-state current, it is possible to reduce the amount of charge leaked from a battery cell that does not belong to the discharge battery cell group, and to suppress a decrease in capacity over time. In addition, the OS transistor is unlikely to break down when a high voltage is applied. Therefore, even if the output voltage of the discharge battery cell group is large, the battery cell BT09 connected to the transistor BT10 to be turned off and the terminal pair BT01 can be insulated.

In FIG. 20, the switching circuit BT05 includes a plurality of transistors BT13, a current control switch BT14, a bus BT15, and a bus BT16. The buses BT15 and BT16 are disposed between the plurality of transistors BT13 and the current control switch BT14. One of the sources or drains of the plurality of transistors BT13 is alternately connected to the buses BT15 and BT16 alternately. The other of the sources or drains of the plurality of transistors BT13 is connected between two adjacent battery cells BT09.

Note that, among the plurality of transistors BT13, the other of the source and the drain of the transistor BT13 located at the uppermost stream is connected to the positive terminal of the battery cell BT09 located at the uppermost stream of the battery unit BT08. In addition, among the plurality of transistors BT13, the other of the source and the drain of the transistor BT13 located on the most downstream side is connected to the negative terminal of the battery cell BT09 located on the most downstream side of the battery unit BT08.

As the transistor BT13, an OS transistor is preferably used similarly to the transistor BT10. Since the OS transistor has a small off-state current, it is possible to reduce the amount of charge leaked from a battery cell that does not belong to the rechargeable battery cell group, and to suppress a decrease in capacity over time. In addition, the OS transistor is unlikely to break down when a high voltage is applied. Therefore, even if the voltage for charging the charged battery cell group is large, the battery cell BT09 to which the transistor BT13 to be turned off and the terminal pair BT02 can be insulated.

The current control switch BT14 has a switch pair BT17 and a switch pair BT18. One end of the switch pair BT17 is connected to the terminal B1. The other end of the switch pair BT17 is branched by two switches. One switch is connected to the bus BT15 and the other switch is connected to the bus BT16. One end of the switch pair BT18 is connected to the terminal B2. The other end of the switch pair BT18 is branched by two switches. One switch is connected to the bus BT15 and the other switch is connected to the bus BT16.

As the switches included in the switch pair BT17 and the switch pair BT18, OS transistors are preferably used as in the transistors BT10 and BT13.

The switching circuit BT05 connects the charging battery cell group and the terminal pair BT02 by controlling the combination of the on / off state of the transistor BT13 and the current control switch BT14 according to the control signal S2.

As an example, the switching circuit BT05 connects the rechargeable battery cell group and the terminal pair BT02 as follows.

The switching circuit BT05 brings the transistor BT13 connected to the positive terminal of the battery cell BT09 located most upstream in the charging battery cell group into a conductive state in response to the control signal S2 applied to the gates of the plurality of transistors BT10. . Further, the switching circuit BT05 conducts the transistor BT13 connected to the negative terminal of the battery cell BT09 located most downstream in the charging battery cell group in response to the control signal S2 applied to the gates of the plurality of transistors BT10. To.

The polarity of the voltage applied to the terminal pair BT02 can vary depending on the configuration of the discharge battery cell group connected to the terminal pair BT01 and the transformer circuit BT07. Moreover, in order to flow an electric current in the direction which charges a rechargeable battery cell group, it is necessary to connect terminals of the same polarity between the terminal pair BT02 and the rechargeable battery cell group. Therefore, the current control switch BT14 is controlled to switch the connection destination of the switch pair BT17 and the switch pair BT18 according to the polarity of the voltage applied to the terminal pair BT02 by the control signal S2.

As an example, a description will be given of a state where a voltage is applied to the terminal pair BT02 so that the terminal B1 is a positive electrode and the terminal B2 is a negative electrode. At this time, when the battery cell BT09 on the most downstream side of the battery unit BT08 is a charged battery cell group, the switch pair BT17 is controlled to be connected to the positive terminal of the battery cell BT09 by the control signal S2. That is, the switch connected to the bus BT16 of the switch pair BT17 is turned on, and the switch connected to the bus BT15 of the switch pair BT17 is turned off. On the other hand, the switch pair BT18 is controlled to be connected to the negative terminal of the battery cell BT09 by the control signal S2. That is, the switch connected to the bus BT15 of the switch pair BT18 is turned on, and the switch connected to the bus BT16 of the switch pair BT18 is turned off. In this way, terminals having the same polarity are connected between the terminal pair BT02 and the rechargeable battery cell group. And the direction of the electric current which flows from terminal pair BT02 is controlled so that it may become a direction which charges a charging battery cell group.

Further, the current control switch BT14 may be included in the switching circuit BT04 instead of the switching circuit BT05. In this case, the polarity of the voltage applied to the terminal pair BT02 is controlled by controlling the polarity of the voltage applied to the terminal pair BT01 in accordance with the current control switch BT14 and the control signal S1. The current control switch BT14 controls the direction of current flowing from the terminal pair BT02 to the rechargeable battery cell group.

FIG. 21 is a circuit diagram showing a configuration example of the switching circuit BT04 and the switching circuit BT05, which is different from FIG.

In FIG. 21, the switching circuit BT04 includes a plurality of transistor pairs BT21, a bus BT24, and a bus BT25. The bus BT24 is connected to the terminal A1. The bus BT25 is connected to the terminal A2. One ends of the plurality of transistor pairs BT21 are branched by a transistor BT22 and a transistor BT23, respectively. One of the source and the drain of the transistor BT22 is connected to the bus BT24. One of the source and the drain of the transistor BT23 is connected to the bus BT25. The other ends of the plurality of transistor pairs are connected between two adjacent battery cells BT09. Of the plurality of transistor pairs BT21, the other end of the transistor pair BT21 located at the most upstream is connected to the positive terminal of the battery cell BT09 located at the most upstream of the battery unit BT08. Moreover, the other end of the transistor pair BT21 located on the most downstream side of the plurality of transistor pairs BT21 is connected to the negative electrode terminal of the battery cell BT09 located on the most downstream side of the battery unit BT08.

The switching circuit BT04 switches the connection destination of the transistor pair BT21 to either the terminal A1 or the terminal A2 by switching the conduction / non-conduction state of the transistor BT22 and the transistor BT23 according to the control signal S1. Specifically, when the transistor BT22 is in a conductive state, the transistor BT23 is in a nonconductive state, and the connection destination is the terminal A1. On the other hand, when the transistor BT23 is in a conductive state, the transistor BT22 is in a nonconductive state, and the connection destination is the terminal A2. Which of the transistors BT22 and BT23 is turned on is determined by the control signal S1.

Two transistor pairs BT21 are used to connect the terminal pair BT01 and the discharge battery cell group. Specifically, the connection destination of the two transistor pairs BT21 is determined based on the control signal S1, whereby the discharge battery cell group and the terminal pair BT01 are connected. The connection destinations of the two transistor pairs BT21 are controlled by the control signal S1 so that one is the terminal A1 and the other is the terminal A2.

The switching circuit BT05 includes a plurality of transistor pairs BT31, a bus BT34, and a bus BT35. The bus BT34 is connected to the terminal B1. The bus BT35 is connected to the terminal B2. One ends of the plurality of transistor pairs BT31 are branched by a transistor BT32 and a transistor BT33, respectively. One end branched by the transistor BT32 is connected to the bus BT34. One end branched by the transistor BT33 is connected to the bus BT35. The other ends of the plurality of transistor pairs BT31 are connected between two adjacent battery cells BT09. Note that, among the plurality of transistor pairs BT31, the other end of the uppermost transistor pair BT31 is connected to the positive terminal of the battery cell BT09 located at the uppermost stream of the battery unit BT08. Moreover, the other end of the transistor pair BT31 located on the most downstream side of the plurality of transistor pairs BT31 is connected to the negative electrode terminal of the battery cell BT09 located on the most downstream side of the battery unit BT08.

The switching circuit BT05 switches the connection destination of the transistor pair BT31 to either the terminal B1 or the terminal B2 by switching the conduction / non-conduction state of the transistor BT32 and the transistor BT33 according to the control signal S2. Specifically, when the transistor BT32 is in a conductive state, the transistor BT33 is in a nonconductive state, and the connection destination is the terminal B1. On the other hand, when the transistor BT33 is in a conductive state, the transistor BT32 is in a nonconductive state, and the connection destination is the terminal B2. Which of the transistor BT32 and the transistor BT33 becomes conductive is determined by the control signal S2.

Two transistor pairs BT31 are used to connect the terminal pair BT02 and the rechargeable battery cell group. Specifically, the connection destination of the two transistor pairs BT31 is determined based on the control signal S2, whereby the rechargeable battery cell group and the terminal pair BT02 are connected. The connection destinations of the two transistor pairs BT31 are controlled by the control signal S2 so that one is the terminal B1 and the other is the terminal B2.

The connection destination of each of the two transistor pairs BT31 is determined by the polarity of the voltage applied to the terminal pair BT02. Specifically, when a voltage is applied to the terminal pair BT02 such that the terminal B1 is a positive electrode and the terminal B2 is a negative electrode, the upstream transistor pair BT31 is in a conductive state and the transistor BT33 is in a nonconductive state. It is controlled by the control signal S2 so as to be in a state. On the other hand, the downstream transistor pair BT31 is controlled by the control signal S2 so that the transistor BT33 is conductive and the transistor BT32 is nonconductive. Further, when a voltage is applied to the terminal pair BT02 so that the terminal B1 is a negative electrode and the terminal B2 is a positive electrode, the upstream transistor pair BT31 has the transistor BT33 in a conductive state and the transistor BT32 in a nonconductive state. It is controlled by the control signal S2. On the other hand, the transistor pair BT31 on the downstream side is controlled by the control signal S2 so that the transistor BT32 is conductive and the transistor BT33 is nonconductive. In this way, terminals having the same polarity are connected between the terminal pair BT02 and the rechargeable battery cell group. And the direction of the electric current which flows from terminal pair BT02 is controlled so that it may become a direction which charges a charging battery cell group.

The transformation control circuit BT06 controls the operation of the transformation circuit BT07. The transformation control circuit BT06 generates a transformation signal S3 for controlling the operation of the transformation circuit BT07 based on the number of battery cells BT09 included in the discharge battery cell group and the number of battery cells BT09 included in the charge battery cell group. And output to the transformer circuit BT07.

When the number of battery cells BT09 included in the discharge battery cell group is greater than the number of battery cells BT09 included in the charge battery cell group, an excessively large charge voltage is applied to the charge battery cell group. Need to prevent. Therefore, the transformation control circuit BT06 outputs a transformation signal S3 that controls the transformation circuit BT07 so as to step down the discharge voltage (Vdis) within a range in which the rechargeable battery cell group can be charged.

Further, when the number of battery cells BT09 included in the discharge battery cell group is equal to or less than the number of battery cells BT09 included in the charge battery cell group, a charging voltage necessary for charging the charge battery cell group is ensured. There is a need. Therefore, the transformation control circuit BT06 outputs a transformation signal S3 that controls the transformation circuit BT07 so as to boost the discharge voltage (Vdis) in a range where an excessive charging voltage is not applied to the charging battery cell group.

In addition, the voltage value used as the excessive charging voltage can be determined in view of the product specifications of the battery cell BT09 used in the battery unit BT08. The voltage stepped up and stepped down by the transformer circuit BT07 is applied to the terminal pair BT02 as a charging voltage (Vcha).

Here, an operation example of the transformation control circuit BT06 in the present embodiment will be described with reference to FIGS. 22A to 22C are conceptual diagrams for explaining an operation example of the transformation control circuit BT06 corresponding to the discharge battery cell group and the charge battery cell group described with reference to FIGS. 19A to 19C. FIG. 22A to 22C show the battery control unit BT41. As described above, the battery control unit BT41 includes the terminal pair BT01, the terminal pair BT02, the switching control circuit BT03, the switching circuit BT04, the switching circuit BT05, the transformation control circuit BT06, and the transformation circuit BT07. The

In the example shown in FIG. 22A, as described with reference to FIG. 19A, three continuous high-voltage cells a to c and one low-voltage cell d are connected in series. In this case, as described with reference to FIG. 19A, the switching control circuit BT03 determines the high voltage cells a to c as the discharge battery cell group and the low voltage cell d as the charge battery cell group. Then, the transformation control circuit BT06 determines the discharge voltage (Vdis) based on the ratio of the number of battery cells BT09 included in the charging electric cell group when the number of battery cells BT09 included in the discharge battery cell group is used as a reference. The step-up / step-down ratio N is calculated.

When the number of battery cells BT09 included in the discharge battery cell group is greater than the number of battery cells BT09 included in the charge battery cell group, the discharge battery is applied as it is to the terminal pair BT02 without being transformed. An excessive voltage may be applied to the battery cell BT09 included in the cell group via the terminal pair BT02. Therefore, in the case as shown in FIG. 22A, it is necessary to lower the charging voltage (Vcha) applied to the terminal pair BT02 below the discharging voltage. Furthermore, in order to charge the charging battery cell group, the charging voltage needs to be larger than the total voltage of the battery cells BT09 included in the charging battery cell group. Therefore, the transformation control circuit BT06 has a step-up / step-down ratio N larger than the ratio of the number of battery cells BT09 included in the charging electric cell group when the number of battery cells BT09 included in the discharge battery cell group is used as a reference. Set.

The transformation control circuit BT06 sets the step-up / step-down ratio N to 1 to the ratio of the number of battery cells BT09 included in the charging electric cell group when the number of battery cells BT09 included in the discharge battery cell group is used as a reference. It is preferable to increase it by about 10%. At this time, the charging voltage is larger than the voltage of the charging battery cell group, but in practice, the charging voltage is equal to the voltage of the charging battery cell group. However, in order to make the voltage of the charging battery cell group equal to the charging voltage in accordance with the step-up / down ratio N, the transformation control circuit BT06 passes a current for charging the charging battery cell group. This current is a value set in the transformation control circuit BT06.

In the example shown in FIG. 22A, the number of battery cells BT09 included in the discharge battery cell group is three, and the number of battery cells BT09 included in the charge battery cell group is one. BT06 calculates a value slightly larger than 1/3 as the step-up / step-down ratio N. Then, the transformation control circuit BT06 steps down the discharge voltage according to the step-up / step-down ratio N, and outputs a transformation signal S3 that converts it to a charging voltage to the transformation circuit BT07. Then, the transformer circuit BT07 applies the charging voltage transformed according to the transformation signal S3 to the terminal pair BT02. Then, the battery cell BT09 included in the charging battery cell group is charged by the charging voltage applied to the terminal pair BT02.

Also in the examples shown in FIGS. 22B and 22C, the step-up / step-down ratio N is calculated as in FIG. 22A. In the examples shown in FIGS. 22B and 22C, the number of battery cells BT09 included in the discharge battery cell group is equal to or less than the number of battery cells BT09 included in the charge battery cell group. N is 1 or more. Therefore, in this case, the transformation control circuit BT06 outputs a transformation signal S3 that boosts the discharge voltage and converts it to a received voltage.

Transformer circuit BT07 converts the discharge voltage applied to terminal pair BT01 into a charge voltage based on transform signal S3. Then, the transformer circuit BT07 applies the converted charging voltage to the terminal pair BT02. Here, the transformer circuit BT07 electrically insulates between the terminal pair BT01 and the terminal pair BT02. Thereby, the transformer circuit BT07 has the absolute voltage of the negative terminal of the battery cell BT09 located most downstream in the discharge battery cell group and the negative terminal of the battery cell BT09 located most downstream in the charge battery cell group. Prevents short circuit due to difference from absolute voltage. Furthermore, as described above, the transformer circuit BT07 converts the discharge voltage, which is the total voltage of the discharge battery cell group, into a charge voltage based on the transform signal S3.

In addition, the transformer circuit BT07 may be an insulation type DC (Direct Current) -DC converter, for example. In this case, the transformation control circuit BT06 controls the charging voltage converted by the transformation circuit BT07 by outputting a signal for controlling the on / off ratio (duty ratio) of the isolated DC-DC converter as the transformation signal S3. .

Insulated DC-DC converters include flyback method, forward method, RCC (Ringing Choke Converter) method, push-pull method, half-bridge method, and full-bridge method. An appropriate method is selected according to the size.

FIG. 23 shows the configuration of a transformer circuit BT07 using an insulated DC-DC converter. Insulated DC-DC converter BT51 has switch part BT52 and transformer part BT53. The switch unit BT52 is a switch that switches on / off the operation of the isolated DC-DC converter, and is realized by using, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), a bipolar transistor, or the like. Further, the switch unit BT52 periodically switches between the on state and the off state of the isolated DC-DC converter BT51 based on the transform signal S3 that is output from the transform control circuit BT06 and controls the on / off ratio. Note that the switch unit BT52 can take various configurations depending on the method of the insulation type DC-DC converter used. The transformer unit BT53 converts the discharge voltage applied from the terminal pair BT01 into a charge voltage. Specifically, the transformer unit BT53 operates in conjunction with the on / off state of the switch unit BT52, and converts the discharge voltage into a charge voltage according to the on / off ratio. This charging voltage increases as the time in which the switch is turned on in the switching period of the switch unit BT52 is longer. On the other hand, the charging voltage becomes smaller as the time for which the on state is turned on is shorter in the switching period of the switch unit BT52. In the case of using an insulated DC-DC converter, the terminal pair BT01 and the terminal pair BT02 can be insulated from each other inside the transformer unit BT53.

A processing flow of the power storage device BT00 in the present embodiment will be described with reference to FIG. FIG. 24 is a flowchart showing a process flow of the power storage device BT00.

First, the power storage device BT00 acquires a voltage measured for each of the plurality of battery cells BT09 (step S001). Then, the power storage device BT00 determines whether or not a start condition for the operation of aligning the voltages of the plurality of battery cells BT09 is satisfied (step S002). The start condition can be, for example, whether or not the difference between the maximum value and the minimum value of the voltage measured for each of the plurality of battery cells BT09 is equal to or greater than a predetermined threshold. If this start condition is not satisfied (step S002: NO), the voltage of each battery cell BT09 is balanced, and the power storage device BT00 does not perform the subsequent processing. On the other hand, when the start condition is satisfied (step S002: YES), the power storage device BT00 executes a process for aligning the voltages of the battery cells BT09. In this process, the power storage device BT00 determines whether each battery cell BT09 is a high voltage cell or a low voltage cell based on the measured voltage for each cell (step S003). Then, the power storage device BT00 determines a discharge battery cell group and a charge battery cell group based on the determination result (step S004). Further, power storage device BT00 has a control signal S1 for setting the determined discharge battery cell group as a connection destination of terminal pair BT01, and a control signal S2 for setting the determined charge battery cell group as a connection destination of terminal pair BT02. Generate (step S005). The power storage device BT00 outputs the generated control signal S1 and control signal S2 to the switching circuit BT04 and the switching circuit BT05, respectively. Then, the switching circuit BT04 connects the terminal pair BT01 and the discharge battery cell group, and the switching circuit BT05 connects the terminal pair BT02 and the discharge battery cell group (step S006). The power storage device BT00 generates the transformation signal S3 based on the number of battery cells BT09 included in the discharge battery cell group and the number of battery cells BT09 included in the charge battery cell group (step S007). Then, the power storage device BT00 converts the discharge voltage applied to the terminal pair BT01 into a charging voltage based on the transformation signal S3, and applies it to the terminal pair BT02 (step S008). Thereby, the electric charge of the discharge battery cell group is moved to the charge battery cell group.

Further, in the flowchart of FIG. 24, a plurality of steps are described in order, but the execution order of each step is not limited to the description order.

As described above, according to the present embodiment, when the charge is transferred from the discharge battery cell group to the charge battery cell group, the charge is temporarily accumulated from the discharge battery cell group and then released to the charge battery cell group as in the capacitor system. No configuration is required. Thereby, the charge transfer efficiency per unit time can be improved. In addition, the discharge battery cell group and the charge battery cell group are individually switched by the switching circuit BT04 and the switching circuit BT05.

Further, the transformer circuit BT07 converts the discharge voltage applied to the terminal pair BT01 based on the number of battery cells BT09 included in the discharge battery cell group and the number of battery cells BT09 group included in the charge battery cell group. And applied to the terminal pair BT02. Thereby, no matter how the discharge-side and charge-side battery cells BT09 are selected, the movement of charges can be realized without any problem.

Furthermore, by using OS transistors for the transistors BT10 and BT13, the amount of charge leaked from the battery cell BT09 that does not belong to the charge battery cell group and the discharge battery cell group can be reduced. Thereby, the fall of the capacity | capacitance of the battery cell BT09 which does not contribute to charge and discharge can be suppressed. In addition, the OS transistor has less variation in characteristics with respect to heat than the Si transistor. Thereby, even if the temperature of battery cell BT09 rises, normal operation | movement, such as switching of the conduction | electrical_connection state and non-conduction state according to control signal S1, S2, can be performed.

This embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 4)
In this embodiment, usage examples of the power storage device of one embodiment of the present invention will be described with reference to FIGS.

The power storage device of one embodiment of the present invention can be used for an electronic device or a lighting device, for example. In the power storage device of one embodiment of the present invention, the electrolytic solution is hardly decomposed and the irreversible capacity is reduced. Therefore, the electronic device and the lighting device can be used for a long time by one charge. Moreover, since the capacity | capacitance reduction accompanying a charging / discharging cycle is suppressed, even if it repeats charging, it is difficult to shorten the usable time. In addition, the safety and reliability of electronic devices and lighting devices can be improved.

Examples of the electronic device include a television device (also referred to as a television or a television receiver), a monitor for a computer, a digital camera, a digital video camera, a digital photo frame, a mobile phone (also referred to as a mobile phone or a mobile phone device). ), Large game machines such as portable game machines, portable information terminals, sound reproducing devices, and pachinko machines.

Since the power storage device of one embodiment of the present invention has flexibility, the power storage device itself, or the electronic device or the lighting device using the power storage device can be used as an interior or exterior wall of a house or a building, It is also possible to incorporate along the curved surface of the exterior.

FIG. 25A illustrates an example of a mobile phone. A mobile phone 7400 is provided with a display portion 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. Note that the mobile phone 7400 includes a power storage device 7407.

FIG. 25B illustrates a state where the mobile phone 7400 is bent. When the cellular phone 7400 is deformed by an external force to bend the whole, the power storage device 7407 provided therein is also curved. The power storage device 7407 is a thin storage battery. The power storage device 7407 is fixed in a bent state. FIG. 25C illustrates the power storage device 7407 in a curved state.

FIG. 25D illustrates an example of a bangle display device. A portable display device 7100 includes a housing 7101, a display portion 7102, operation buttons 7103, and a power storage device 7104. FIG. 25E illustrates a state of the power storage device 7104 bent.

FIG. 25F illustrates an example of a wristwatch-type portable information terminal. A portable information terminal 7200 includes a housing 7201, a display portion 7202, a band 7203, a buckle 7204, operation buttons 7205, an input / output terminal 7206, and the like.

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

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

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

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

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

The display portion 7202 of the portable information terminal 7200 includes the power storage device of one embodiment of the present invention. For example, the power storage device 7104 illustrated in FIG. 25E can be incorporated in the housing 7201 in a curved state or in the band 7203 in a bendable state.

FIG. 25G illustrates an example of an armband display device. The display device 7300 includes the display portion 7304 and includes the power storage device of one embodiment of the present invention. In addition, the display device 7300 can include a touch sensor in the display portion 7304 and can function as a portable information terminal.

The display portion 7304 has a curved display surface, and can perform display along the curved display surface. In addition, the display device 7300 can change the display status through short-range wireless communication that is a communication standard.

In addition, the display device 7300 includes an input / output terminal, and can directly exchange data with another information terminal via a connector. Charging can also be performed via an input / output terminal. Note that the charging operation may be performed by wireless power feeding without using the input / output terminal.

FIGS. 26A and 26B illustrate an example of a tablet terminal that can be folded. A tablet terminal 9600 illustrated in FIGS. 26A and 26B includes a pair of housings 9630, a movable portion 9640 connecting the pair of housings 9630, a display portion 9631a, a display portion 9631b, a display mode switching switch 9626, and a power switch. 9627, a power-saving mode switching switch 9625, a fastener 9629, and an operation switch 9628. Fig. 26A shows a state in which the tablet terminal 9600 is opened, and Fig. 26B closes the tablet terminal 9600. Shows the state.

In addition, the tablet terminal 9600 includes a power storage unit 9635 inside the housing 9630. The power storage unit 9635 is provided from the one housing 9630 to the other housing 9630 through the movable portion 9640.

Part of the display portion 9631 a can be a touch panel region 9632 a and data can be input when a displayed operation key 9638 is touched. Note that in the display portion 9631a, for example, a structure in which half of the regions have a display-only function and a structure in which the remaining half of the region has a touch panel function is shown, but the structure is not limited thereto. The entire region of the display portion 9631a may have a touch panel function. For example, a keyboard button can be displayed on the entire surface of the display portion 9631a to be a touch panel, and the display portion 9631b can be used as a display screen.

Further, in the display portion 9631b, as in the display portion 9631a, part of the display portion 9631b can be a touch panel region 9632b. Further, a keyboard button can be displayed on the display portion 9631b by touching a position where the keyboard display switching button 9539 on the touch panel is displayed with a finger or a stylus.

Touch input can be performed simultaneously on the touch panel region 9632a and the touch panel region 9632b.

A display mode switching switch 9626 can switch a display direction such as a vertical display or a horizontal display, and can select a monochrome display or a color display. The power saving mode change-over switch 9625 can optimize the display luminance in accordance with the amount of external light in use detected by an optical sensor incorporated in the tablet terminal 9600. The tablet terminal may include not only an optical sensor but also other detection devices such as a gyroscope, an acceleration sensor, and other sensors that detect inclination.

FIG. 26A illustrates an example in which the display areas of the display portion 9631a and the display portion 9631b are the same; however, there is no particular limitation, and the size of one display portion and the other display portion may be different. The display quality may also be different. For example, one display panel may be capable of displaying images with higher definition than the other.

FIG. 26B illustrates a closed state, in which the tablet terminal includes a charge / discharge control circuit 9634 including a housing 9630, a solar battery 9633, and a DCDC converter 9636. Further, as the power storage unit 9635, the power storage device of one embodiment of the present invention is used.

Note that the tablet terminal 9600 can be folded in two, so that the pair of housings 9630 can be folded when not in use. By folding, the display portion 9631a and the display portion 9631b can be protected; thus, durability of the tablet terminal 9600 can be improved. Further, the power storage unit 9635 using the power storage unit of one embodiment of the present invention has flexibility, and thus the charge / discharge capacity is hardly reduced even when bending and stretching are repeated. Therefore, a tablet terminal with excellent reliability can be provided.

In addition, the tablet terminal shown in FIGS. 26A and 26B has a function of displaying various information (still images, moving images, text images, etc.) on the display unit, calendar, date, time, etc. Can be displayed on the display unit, a touch input function for touch input operation or editing of information displayed on the display unit, a function for controlling processing by various software (programs), and the like.

Electric power can be supplied to the touch panel, the display unit, the video signal processing unit, or the like by the solar battery 9633 mounted on the surface of the tablet terminal. Note that the solar battery 9633 can be provided on one or both surfaces of the housing 9630 and is preferable because the power storage unit 9635 can be charged efficiently. Note that as the power storage unit 9635, when a lithium ion battery is used, there is an advantage that the size can be reduced.

The structure and operation of the charge / discharge control circuit 9634 illustrated in FIG. 26B are described with reference to a block diagram in FIG. FIG. 26C illustrates the solar battery 9633, the power storage unit 9635, the DCDC converter 9636, the converter 9637, the switches SW1 to SW3, and the display portion 9631. The power storage unit 9635, the DCDC converter 9636, the converter 9637, and the switches SW1 to SW3 are illustrated. SW3 corresponds to the charge / discharge control circuit 9634 shown in FIG.

First, an example of operation in the case where power is generated by the solar cell 9633 using external light is described. The power generated by the solar battery is boosted or lowered by the DCDC converter 9636 so as to be a voltage for charging the power storage unit 9635. When power from the solar cell 9633 is used for the operation of the display portion 9631, the switch SW1 is turned on, and the converter 9637 increases or decreases the voltage required for the display portion 9631. Further, in the case where display on the display portion 9631 is not performed, the power storage unit 9635 may be charged by turning off the switch SW1 and turning on the switch SW2.

Note that although the solar cell 9633 is described as an example of a power generation unit, the power storage unit 9635 is charged by another power generation unit such as a piezoelectric element (piezo element) or a thermoelectric conversion element (Peltier element). It may be a configuration. For example, a non-contact power transmission module that wirelessly (contactlessly) transmits and receives power for charging and other charging means may be combined.

FIG. 27 illustrates an example of another electronic device. In FIG 27, a display device 8000 is an example of an electronic device including the power storage device 8004 according to one embodiment of the present invention. Specifically, the display device 8000 corresponds to a display device for TV broadcast reception, and includes a housing 8001, a display portion 8002, a speaker portion 8003, a power storage device 8004, and the like. A power storage device 8004 according to one embodiment of the present invention is provided inside the housing 8001. The display device 8000 can receive power from a commercial power supply. Alternatively, the display device 8000 can use power stored in the power storage device 8004. Thus, the display device 8000 can be used by using the power storage device 8004 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

A display portion 8002 includes a liquid crystal display device, a light-emitting device including a light-emitting element such as an organic EL element, an electrophoretic display device, a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), and an FED (Field Emission Display). A semiconductor display device such as) can be used.

The display device includes all information display devices such as a personal computer and an advertisement display in addition to a TV broadcast reception.

In FIG 27, a stationary lighting device 8100 is an example of an electronic device including the power storage device 8103 according to one embodiment 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. 27 illustrates the case where the power storage device 8103 is provided inside the ceiling 8104 where the housing 8101 and the light source 8102 are installed, the power storage device 8103 is provided inside the housing 8101. May be. The lighting device 8100 can receive power from a commercial power supply. Alternatively, the lighting device 8100 can use power stored in the power storage device 8103. Therefore, the lighting device 8100 can be used by using the power storage device 8103 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

Note that although a stationary lighting device 8100 provided on the ceiling 8104 is illustrated in FIG. 27, the power storage device according to one embodiment of the present invention is not provided on the ceiling 8104, for example, on the sidewall 8105, the floor 8106, the window 8107, or the like. It can be used for a stationary lighting device provided, or can be used for a desktop lighting device or the like.

The light source 8102 can be an artificial light source that artificially obtains light using electric power. Specifically, discharge lamps such as incandescent bulbs and fluorescent lamps, and light emitting elements such as LEDs and organic EL elements are examples of the artificial light source.

In FIG 27, an air conditioner including an indoor unit 8200 and an outdoor unit 8204 is an example of an electronic device using the power storage device 8203 according to one embodiment of the present invention. Specifically, the indoor unit 8200 includes a housing 8201, an air outlet 8202, a power storage device 8203, and the like. FIG. 27 illustrates the case where the power storage device 8203 is provided in the indoor unit 8200, but the power storage device 8203 may be provided in the outdoor unit 8204. Alternatively, the power storage device 8203 may be provided in both the indoor unit 8200 and the outdoor unit 8204. The air conditioner can receive power from a commercial power supply. Alternatively, the air conditioner can use power stored in the power storage device 8203. In particular, in the case where 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 embodiment of the present invention can be disconnected even when power supply from a commercial power source cannot be received due to a power failure or the like. By using it as a power failure power supply, an air conditioner can be used.

In FIG. 27, a separate type air conditioner composed of an indoor unit and an outdoor unit is illustrated, but an integrated air conditioner having the functions of the indoor unit and the outdoor unit in one housing is shown. The power storage device according to one embodiment of the present invention can also be used.

In FIG 27, an electric refrigerator-freezer 8300 is an example of an electronic device including the power storage device 8304 according to one embodiment of the present invention. Specifically, the electric refrigerator-freezer 8300 includes a housing 8301, a refrigerator door 8302, a freezer door 8303, a power storage device 8304, and the like. In FIG. 27, the power storage device 8304 is provided inside the housing 8301. The electric refrigerator-freezer 8300 can receive power from a commercial power supply. Alternatively, the electric refrigerator-freezer 8300 can use power stored in the power storage device 8304. Therefore, the electric refrigerator-freezer 8300 can be used by using the power storage device 8304 according to one embodiment of the present invention as an uninterruptible power supply even when power cannot be supplied from a commercial power supply due to a power failure or the like.

Note that high-frequency heating devices such as a microwave oven and electronic devices such as an electric rice cooker require high power in a short time. Therefore, by using the power storage device according to one embodiment of the present invention as an auxiliary power source for assisting electric power that cannot be supplied by a commercial power source, a breaker of the commercial power source can be prevented from falling when the electronic device is used.

In addition, when the electronic equipment is not used, especially during the time when the ratio of the actually used power amount (referred to as the power usage rate) is low in the total power amount that can be supplied by the commercial power supply source. By storing electric power in the apparatus, it is possible to suppress an increase in the power usage rate outside the above time period. For example, in the case of the electric refrigerator-freezer 8300, electric power is stored in the power storage device 8304 at night when the temperature is low and the refrigerator door 8302 and the refrigerator door 8303 are not opened and closed. In the daytime when the temperature rises and the refrigerator door 8302 and the freezer door 8303 are opened and closed, the power storage device 8304 is used as an auxiliary power source, so that the daytime power usage rate can be kept low.

The power storage device of one embodiment of the present invention can also be mounted on a vehicle.

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

28A and 28B illustrate a vehicle including the power storage device of one embodiment of the present invention. A car 8400 illustrated in FIG. 28A is an electric car using an electric motor as a power source for traveling. Or it is a hybrid vehicle which can select and use an electric motor and an engine suitably as a motive power source for driving | running | working. By using one embodiment of the present invention, a vehicle having a long cruising distance can be realized. The automobile 8400 includes a power storage device. The power storage device can not only drive an electric motor but also supply power to a light-emitting device such as a headlight 8401 or a room light (not shown).

The power storage device can supply power to a display device such as a speedometer or a tachometer included in the automobile 8400. The power storage device can supply power to a semiconductor device such as a navigation system included in the automobile 8400.

A car 8500 illustrated in FIG. 28B can charge a power storage device included in the car 8500 by receiving power from an external charging facility by a plug-in method, a non-contact power feeding method, or the like. FIG. 28B illustrates a state where charging is performed from the ground-mounted charging device 8021 to the power storage device mounted on the automobile 8500 through the cable 8022. When charging, the charging method, connector standard, and the like may be appropriately performed by a predetermined method such as CHAdeMO (registered trademark) or a combo. The charging device 8021 may be a charging station provided in a commercial facility, or may be a household power source. For example, the power storage device 8024 mounted on the automobile 8500 can be charged by power supply from the outside by plug-in technology. Charging can be performed by converting AC power into DC power via a converter such as an ACDC converter.

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

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

This embodiment can be combined with any of the other embodiments as appropriate.

In this example, a power storage device of one embodiment of the present invention was manufactured and the characteristics thereof were evaluated. The power storage device manufactured in this example is a thin storage battery.

A pair of positive and negative electrodes was used for the power storage device of this example. In addition, the size of the surface on the positive electrode side of the negative electrode was made larger than the size of the surface on the negative electrode side of the positive electrode.

In this example, two power storage devices were manufactured: a sample to which one embodiment of the present invention was applied (Sample A to Sample C) and a comparative sample (Comparative Sample D and Comparative Sample E) as a comparative example. The cation used for the electrolyte is different between the sample and the comparative sample.

First, a method for manufacturing a positive electrode will be described, and then a method for manufacturing a negative electrode will be described.

As the positive electrode active material, LiFePO ₄ having a specific surface area of 9.2 m ² / g was used, PVdF was used as a binder, and graphene was used as a conductive additive. Note that graphene is graphene oxide when the paste is manufactured, and is applied to the positive electrode current collector and then subjected to a reduction treatment to obtain graphene. The composition of the paste for producing the electrode was LiFePO ₄ : graphene oxide: PVdF = 94.4: 0.6: 5.0 (% by weight).

First, the graphene oxide powder and the solvent NMP were kneaded using a kneader to obtain a first mixture.

Next, an active material was added to the first mixture, and kneading was performed using a kneader to obtain a second mixture.

Next, PVdF was added to the second mixture and kneaded using a kneader to obtain a third mixture.

Next, NMP as a solvent was added to the third mixture and kneaded using a kneader to obtain a paste.

Next, the paste was applied to the positive electrode current collector using a continuous coating machine. An aluminum current collector with a film thickness of 18 μm was used as the positive electrode current collector. The positive electrode current collector was previously undercoated. The coating speed was 1 m / min.

Thereafter, the solvent was vaporized using a drying furnace (the solvent was removed). The conditions at that time were 80 ° C. and 4 minutes. Thereafter, the electrode was reduced.

As reduction conditions, first, chemical reduction was performed, and then thermal reduction was performed. The solution used for the chemical reduction was a solvent in which NMP: water was mixed at a ratio of 9: 1 as a solvent, and ascorbic acid and LiOH were added to concentrations of 77 mmol / L and 73 mmol / L, respectively. The chemical reduction treatment was performed at 60 ° C. for 1 hour. Then, it wash | cleaned with ethanol and the solvent was vaporized at room temperature under the pressure reduction atmosphere. Thermal reduction was performed at 170 ° C. for 10 hours under a reduced pressure atmosphere.

Next, the positive electrode active material layer was pressed by a roll press method to be consolidated. The positive electrode was produced by the above process.

As the negative electrode active material, spheroidized natural graphite having a specific surface area of 6.3 m ² / g and an average particle size of 15 μm was used. Moreover, sodium carboxymethylcellulose (CMC-Na) and SBR were used as a binder. The polymerization degree of CMC-Na used was 600 to 800, and the aqueous solution viscosity when used as a 1 wt% aqueous solution was a value in the range of 300 mPa · s to 500 mPa · s. The composition of the paste for producing the electrode was graphite: CMC-Na: SBR = 97: 1.5: 1.5 (% by weight).

First, CMC-Na powder and an active material were mixed and kneaded with a kneader to obtain a first mixture.

Next, a small amount of water was added to the first mixture and kneaded to obtain a second mixture. Here, solid kneading is kneading with high viscosity.

Next, water was further added and kneaded using a kneader to obtain a third mixture.

Next, a 50 wt% aqueous dispersion of SBR was added and kneaded using a kneader. Thereafter, defoaming was performed under reduced pressure to obtain a paste.

Next, the paste was applied to the negative electrode current collector using a continuous coating machine. A rolled copper foil having a film thickness of 18 μm was used for the negative electrode current collector. The coating speed was 0.75 m / min.

Next, the solvent of the paste applied on the negative electrode current collector was vaporized using a drying furnace. The solvent was vaporized in an air atmosphere, and the temperature and time were treated at 50 ° C. for 120 seconds and then at 80 ° C. for 120 seconds.

Furthermore, the solvent was vaporized under the conditions of 100 ° C. and 10 hours under a reduced pressure atmosphere.

Through the above steps, a negative electrode active material layer was produced on one side of the negative electrode current collector, and a negative electrode was produced.

The active material loading of the positive electrode active material layer used for the sample of this example was 9.7 mg / cm ² , the thickness was 57 μm, and the density was 1.8 g / cm ³ . Moreover, the active material carrying amount of the negative electrode active material layer was 4.7 mg / cm ² , the thickness was 54 μm, and the density was 0.9 g / cm ³ . Note that these are average values of Sample A, Sample B, and Sample C.

The positive electrode active material layer used for the comparative sample of this example had an active material carrying amount of 9.2 mg / cm ² , a thickness of 56 μm, and a density of 1.8 g / cm ³ . Moreover, the active material carrying amount of the negative electrode active material layer was 4.6 mg / cm ² , the thickness was 52 μm, and the density was 0.9 g / cm ³ . These are average values of the comparative sample D and the comparative sample E.

Next, the electrolytic solution used in this example will be described.

In the electrolytic solution of the sample to which one embodiment of the present invention is applied, 1-ethyl-2,3-dimethylimidazolium bis (fluorosulfonyl) amide (abbreviation: 2MeEMI-FSA) represented by the following structural formula is used as a solvent. Lithium bis (trifluoromethanesulfonyl) amide (LiN (CF ₃ SO ₂ ) ₂ , abbreviation: LiTFSA) was used as the electrolyte. LiTFSA was dissolved in 2MeEMI-FSA to prepare an electrolytic solution having a LiTFSA concentration of 1 mol / kg.

For the electrolytic solution of the comparative sample, 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) amide (abbreviation: EMI-FSA) represented by the following structural formula was used as a solvent, and LiTFSA was used as an electrolyte. LiTFSA was dissolved in EMI-FSA to prepare an electrolyte solution with a LiTFSA concentration of 1 mol / kg.

As the separator, solvent-spun recycled cellulose fiber (TF40, manufactured by Nippon Kogyo Paper Industries Co., Ltd.) having a thickness of 50 μm was used. The separator was cut into a rectangular shape with a length of 24 mm and a width of 45 mm. Moreover, the film which coat | covered the resin layer on both surfaces of aluminum was used for the exterior body.

Next, a thin storage battery was produced. The positive electrode, the negative electrode, and the separator were cut. The size of the positive electrode was 41 mm × 20 mm, and the size of the negative electrode was 45 mm × 22 mm.

Next, the positive electrode active material and the negative electrode active material on the tab region were peeled off to expose the current collector.

Next, the exterior body was folded in half, and the stacked positive electrode, separator, and negative electrode were sandwiched. At this time, the positive electrode and the negative electrode were laminated so that the positive electrode active material layer and the negative electrode active material layer face each other.

Next, of the three sides of the outer package, other than the side where the electrolyte solution was injected was joined by heating. At this time, it arrange | positioned so that the sealing layer provided in the lead electrode might overlap with the sealing part of an exterior body.

Thereafter, the exterior body and the positive electrode, the separator, and the negative electrode wrapped with the exterior body were dried. The drying conditions were 80 ° C. and 10 hours under reduced pressure.

Next, an electrolytic solution was injected from one side that was not sealed in an argon gas atmosphere. Thereafter, one side of the outer package was sealed by heating in a reduced-pressure atmosphere.

Through the above process, the power storage device of this example was manufactured.

Next, an aging process of the power storage device of this example was performed. In calculating the rate, the current value of 170 mA / g per weight of the positive electrode active material was set to 1C.

First, constant current charging was performed at a rate of 0.01 C at 25 ° C. Charging conditions were set to 3.2 V as the upper limit.

Then, after degassing by cutting and opening one side of the outer package in an argon atmosphere, one side of the opened outer package was sealed again in a reduced-pressure atmosphere.

Next, constant current charging was performed at a rate of 0.05 C at 25 ° C. The charging condition was 4.0 V as the upper limit. And constant current discharge was performed at a rate of 0.2 C at 25 ° C. The discharge condition was 2.0 V as the lower limit. Furthermore, charging / discharging was performed twice at a rate of 0.2 C at 25 ° C. The charging condition was 4.0 V as the upper limit, and the discharging condition was 2.0 V as the lower limit.

The results of measuring the charge / discharge cycle characteristics of Sample A, Sample B, Comparative Sample D, and Comparative Sample E after the above aging treatment will be described.

The measurement was performed at an evaluation temperature of 25 ° C. using a charge / discharge measuring machine (manufactured by Toyo System Co., Ltd.). Constant current charging was performed with charging condition 4V as the upper limit. The discharge conditions were constant current discharge with 2V as the lower limit. The first charge / discharge was performed at a rate of 0.1C, and the subsequent charge / discharge was performed at a rate of 0.3C. In calculating the rate, the current value of 170 mA / g per weight of the positive electrode active material was set to 1C.

FIG. 29 shows charge / discharge cycle characteristics. In FIG. 29, the horizontal axis represents the number of cycles (times), and the vertical axis represents the discharge capacity (mAh / g).

As shown in FIG. 29, Sample A and Sample B using 2MeEMI as the cation of the electrolytic solution are compared with Comparative Sample D and Comparative Sample E using 1-ethyl-3-methylimidazolium cation as the cation of the electrolytic solution. The cycle characteristics were good.

Moreover, the element contained in the electrolyte solution of the sample B and the comparative sample E after measuring charging / discharging cycling characteristics was analyzed. For the measurement, inductively coupled plasma-mass spectrometry (ICP-MS: Inductively Coupled Plasma-Mass Spectrometry) was used.

In this example, attention was focused on lithium, nickel, and copper in the electrolytic solution. Here, nickel is an element contained in the lead electrode of each sample, and copper is an element contained in the current collector and lead electrode of each sample.

In the electrolyte solution used for Sample B, the detected amounts of nickel and copper were less than the lower limit of measurement.

On the other hand, in the electrolytic solution used for Comparative Sample E, the detected amount of nickel was less than the lower limit of measurement, but the detected amount of copper was 2.48 (mol) when the detected amount of lithium was 100 (mol). )Met.

That is, in sample B, it was found that elution of copper used for the current collector and the like was suppressed as compared with comparative sample E.

Sample B uses 2MeEMI, and Comparative Sample E uses 1-ethyl-3-methylimidazolium cation, so that the electrolytes of Sample B and Comparative Sample E are different.

In 2MeEMI, by substituting the 2-position proton of the imidazolium ring in the 1-ethyl-3-methylimidazolium cation with a less reactive methyl group, the decomposition reaction of the electrolytic solution and the elution of copper of the current collector are performed. It is thought that it was able to be suppressed. Thereby, it is suggested that the sample B was able to obtain better cycle characteristics than the comparative sample E.

From the results of this example, by applying one embodiment of the present invention, it is possible to suppress the decomposition reaction of the electrolytic solution and the elution of copper in the current collector, and to suppress the decrease in capacity accompanying the charge / discharge cycle of the power storage device. all right. This example indicates that a power storage device with a long lifetime can be manufactured by applying one embodiment of the present invention.

The results of measuring the rate characteristics of sample C will be described.

The measurement was performed at an evaluation temperature of 25 ° C. using a charge / discharge measuring machine (manufactured by Toyo System Co., Ltd.). The charging conditions were constant current charging with 4.0V as the upper limit. Charging was performed at a rate of 0.1C. The discharge conditions were constant current discharge with 2.0V as the lower limit. Discharging was performed at 0.1 C, 0.2 C, 0.3 C, 0.4 C, 0.5 C, and 1 C, respectively. In calculating the rate, the current value of 170 mA / g per weight of the positive electrode active material was set to 1C. FIG. 30 shows the discharge capacity for each rate. In FIG. 30, the horizontal axis represents the discharge rate (C), and the vertical axis represents the discharge capacity (mAh / g).

Table 1 shows the value of the discharge capacity at each rate.

From the results of the rate characteristics, the discharge capacity at 0.4 C was about 95% with respect to the discharge capacity at 0.1 C. The discharge capacity at 0.5C was about 76% with respect to the discharge capacity at 0.1C. As described above, in the power storage device to which one embodiment of the present invention is applied, favorable rate characteristics can be obtained.

S1 control signal S2 control signal S3 transformation signal BT00 power storage device BT01 terminal pair BT02 terminal pair BT03 switching control circuit BT04 switching circuit BT05 switching circuit BT06 transformation control circuit BT07 transformation circuit BT08 battery unit BT09 battery cell BT10 transistor BT11 bus BT12 bus BT13 transistor Current control switch BT15 Bus BT16 Bus BT17 Switch pair BT18 Switch pair BT21 Transistor pair BT22 Transistor BT23 Transistor BT24 Bus BT25 Bus BT31 Transistor pair BT32 Transistor BT33 Transistor BT34 Bus BT35 Bus BT41 Battery control unit BT51 Insulation type DC-DC converter BT52 Switch unit BT53 Transformer 115 sealing layer 118 Joint 119 Inlet 281 Tab region 282 Tab region 300 Storage battery 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 500 Battery cell Reference numeral 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 Negative electrode 507 Separator 508 Electrolyte 509 Exterior body 510 Positive electrode lead electrode 511 Negative electrode lead electrode 512 Bonding portion 513 Bending portion 514 Bonding portion 521 Graphene 522 Positive electrode active material 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 608 Insulating plate 609 Insulating plate 611 PTC element 612 Safety valve mechanism 900 Circuit board 910 La Bell 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 980 Storage battery 981 Film 982 Film 990 Storage battery 991 Exterior body 992 Exterior body 993 Winding body 994 Negative electrode 995 Positive electrode 996 Separator 997 Terminal 998 Terminal 1122 Charger 1123 Charger 7100 Portable display device 7101 Case 7102 Display portion 7103 Operation button 7104 Power storage device 7200 Portable information terminal 7201 Case 7202 Display portion 7203 Band 7204 Buckle 7205 Operation button 7206 Input / output Terminal 7207 Icon 7300 Display device 7304 Display unit 7400 Mobile phone 7401 Case 7402 Display unit 7403 Operation button 7 04 External connection port 7405 Speaker 7406 Microphone 7407 Power storage device 8000 Display device 8001 Case 8002 Display unit 8003 Speaker unit 8004 Power storage device 8021 Charging device 8022 Cable 8024 Power storage device 8100 Lighting device 8101 Case 8102 Light source 8103 Power storage device 8104 Ceiling 8105 Side wall 8106 Floor 8107 Window 8200 Indoor unit 8201 Case 8202 Air outlet 8203 Power storage device 8204 Outdoor unit 8300 Electric refrigerator-freezer 8301 Case 8302 Refrigeration room door 8303 Freezer compartment door 8304 Power storage device 8400 Car 8401 Headlight 8500 Car 9600 Tablet type terminal 9625 Switch 9626 Switch 9627 Power switch 9628 Operation switch 9629 Tool 9630 Housing 9631 Display portion 9631a Display Portion 9631b display portion 9632a region 9632b region 9633 solar cell 9634 charge / discharge control circuit 9635 power storage unit 9636 DCDC converter 9537 converter 9638 operation key 9539 button 9640 movable portion

Claims (10)

Having a positive electrode, a negative electrode, and an electrolyte;
The electrolytic solution has a first cation and an anion,
The first cation is a power storage device represented by a structural formula (100).
In claim 1,
The power storage device, wherein the electrolytic solution includes an alkali metal salt. In claim 2,
The power storage device, wherein the alkali metal salt includes a lithium salt. In any one of Claims 1 thru | or 3,
The anion may be a monovalent amide anion, a monovalent methide anion, a fluorosulfonate anion, a fluoroalkylsulfonate anion, a tetrafluoroborate anion, a perfluoroalkylborate anion, a hexafluorophosphate anion, or a perfluoroalkyl phosphorus. A power storage device comprising any one of acid anions. In any one of Claims 1 thru | or 4,
The power storage device, wherein the anion includes a bis (fluorosulfonyl) amide anion or a bis (trifluoromethanesulfonyl) amide anion. In any one of Claims 1 thru | or 5,
The power storage device, wherein the negative electrode includes carbon. In any one of Claims 1 thru | or 6,
The negative electrode is a power storage device including carboxymethyl cellulose and styrene-butadiene rubber. In any one of Claims 1 thru | or 7,
The positive electrode is a power storage device including graphene. In any one of Claims 1 thru | or 8,
The electrolytic solution has a second cation,
The power storage device, wherein the second cation is an imidazolium cation. The power storage device according to any one of claims 1 to 9,
An electronic device having a display device, operation buttons, an external connection port, a speaker, or a microphone.