Lithium ion battery

Abstract

To provide a lithium ion storage battery having good cycle characteristics at high temperatures, a lithium ion storage battery in which the decrease in capacity is suppressed and the life is extended, and a lithium ion storage battery in which the reaction between a positive electrode active material and an electrolyte in the electrolytic solution is suppressed.SOLUTION: A lithium ion battery according to an embodiment of the present invention includes a positive electrode, a negative electrode, and an electrolyte, the positive electrode has an active material, the active material has a metal, and the electrolyte has at least one of LiTFSA and LiFSA. The positive electrode has a current collector, and the current collector has Al. The electrolyte may further include LiPF6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One embodiment of the present invention relates to a lithium-ion storage battery and a manufacturing method thereof.

[0002] Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one aspect relates to an article, a method, or a manufacturing method. One aspect of the present invention is a process, machine, manufacture, or composition. Therefore, the present invention more specifically disclosed herein The technical field of one embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, Examples of the imaging device include an imaging device, a driving method thereof, and a manufacturing method thereof. Cut. [Background technology]

[0003] Examples of storage batteries include nickel-metal hydride batteries, lead-acid batteries, and lithium-ion batteries. can be.

[0004] These batteries are used as power sources for portable information devices such as mobile phones. Among them, lithium-ion batteries are being actively developed because they have high capacity and can be made small. The characteristics required for lithium-ion batteries are high energy density and These include improved cycle characteristics, safety in various operating environments, and improved long-term reliability.

[0005] A lithium-ion battery generally comprises a positive electrode, a negative electrode, an electrolyte, a separator, and an outer casing. The positive electrode and the negative electrode each have a current collector, and each of them contains an active material. These constituent materials determine the performance of the lithium-ion battery, so Development aimed at improving the performance of constituent materials is also being actively carried out.

[0006] As an example of the positive electrode active material, lithium iron phosphate (LiF ePO4), lithium manganese phosphate (LiMnPO4), lithium cobalt phosphate (L Lithium, iron, and manganese oxides such as iCoPO4 and lithium nickel phosphate (LiNiPO4) Phosphate compounds having an olivine type crystal structure containing calcium, cobalt or nickel. is known (see Patent Document 1, Non-Patent Document 1, and Non-Patent Document 2).

[0007] In addition, in lithium-ion batteries, the electrolyte in the electrolyte solution transports carrier ions. A material that can be used is one that has carrier ions. Representative examples of electrolytes Examples include LiPF6, LiClO4, Li(FSO2)2N, LiAsF6, and LiBF 4, LiCF3SO3, Li(CF3SO2)2N, Li(C2F5SO2)2N, etc. There are lithium salts. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 11-25983 [Non-patent literature]

[0009] [Non-Patent Document 1] Byoungwoo Kang, Gerbrand Ceder, "Nature", 2009, Vol.458(12), p.190-193 [Non-Patent Document 2] F. Zhou et al., "Electrochemistry Communications", 2004, 6, p.1144-1148 Summary of the Invention [Problem to be solved by the invention]

[0010] The material selected from the above is used as the positive electrode active material, and the material selected from the above is used as the electrolyte in the electrolyte solution. The materials are used to assemble a lithium-ion storage battery, and the high-temperature cycle characteristic test of the storage battery is performed. It was found that deterioration progressed faster than expected, and the capacity retention rate sometimes decreased significantly. .

[0011] Therefore, after the cycle characteristic test, the storage battery was disassembled and each component was analyzed. The metal used in the active material was detected on the surface of the negative electrode. This is because the electrolyte and the positive electrode active material or the decomposition products of the electrolyte react with the positive electrode active material, causing some of the positive electrode active material to The metal in the battery dissolved into the electrolyte and precipitated on the surface of the negative electrode during repeated charging and discharging. The positive electrode active material deteriorates and the metal is deposited on the negative electrode, causing charge loss. Specifically, the hexahydrate used in the electrolyte reduced the capacity of the battery. Lithium fluorophosphate (LiPF6) produces hydrogen fluoride (HF) upon hydrolysis. It is known that hydrolysis of LiPF6 occurs during high-temperature cycle operation. It is possible that the capacity of the battery decreased due to a reaction between the generated HF and the positive electrode.

[0012] In view of the above, one aspect of the present invention is to provide a lithium ion battery having good cycle characteristics at high temperatures. One of the objectives is to provide a battery that has a long life and suppresses the decrease in capacity. The present invention also aims to provide a lithium ion storage battery. One of the objectives is to provide a lithium ion storage battery in which the reaction is suppressed. One of the objectives is to provide a lithium ion storage battery in which the deterioration of the active material is suppressed. Another object of the present invention is to provide a lithium ion storage battery in which metal deposition on the negative electrode surface is suppressed. In addition, inhibition of the battery reaction caused by the reaction between the positive electrode active material and the electrolyte is suppressed. Another object of the present invention is to provide a lithium-ion storage battery. To provide a method for manufacturing a lithium-ion storage battery having good cycle characteristics at high temperatures Another object of one embodiment of the present invention is to provide a method for preventing a discharge caused by a reaction between a positive electrode active material and an electrolyte solution. The object of the present invention is to provide a method for producing a lithium ion storage battery in which inhibition of the battery reaction caused by the Another embodiment of the present invention is a novel storage battery, a novel power storage device, or a novel storage battery. Another object of the present invention is to provide a novel method for manufacturing a power storage device.

[0013] The description of these problems does not preclude the existence of other problems. The embodiment does not necessarily have to solve all of these problems. The above will become apparent from the description in the specification, drawings, claims, etc. It is possible to extract other issues from the descriptions in the patent, claims, etc. [Means for solving the problem]

[0014] One embodiment of the present invention includes a positive electrode, a negative electrode, and an electrolyte solution. The positive electrode includes an active material. metal, and the electrolyte is lithium bis(trifluoromethanesulfonyl)amide (LiT At least one of lithium bis(fluorosulfonyl)amide (LiFSA) and lithium bis(fluorosulfonyl)amide (LiFSA) It is a lithium-ion storage battery having the above structure.

[0015] In one embodiment of the present invention, the positive electrode has a current collector, and the current collector contains Al. The lithium ion storage battery may be characterized in that the positive electrode includes graphene. In addition, the electrolyte further contains LiPF6. The negative electrode may be a cathode in the form of a cathode. The metal contained in the material may be an unobservable lithium ion battery. a lithium-ion storage battery, characterized in that the material is any one of e, Co, Ni and Mn; In addition, one embodiment of the present invention includes a positive electrode, a negative electrode, and an electrolyte solution, and the positive electrode is an active material. The active material is a metal, and the electrolyte is Li, N, F, S, O, and C. It is a lithium-ion storage battery. Effect of the Invention

[0016] In the lithium ion storage battery according to one embodiment of the present invention, the reaction between the active material of the positive electrode and the electrolyte is suppressed. The deposition of metal contained in the active material of the positive electrode is suppressed on the surface of the negative electrode. In characteristic tests, the progress of degradation was suppressed and a good capacity retention rate was observed. It is an on-storage battery.

[0017] Therefore, one embodiment of the present invention is a lithium ion battery having good cycle characteristics at high temperatures. In addition, it is possible to provide a lithium-ion battery that has a longer life and suppresses the decrease in capacity. In addition, a lithium storage battery in which the reaction between the positive electrode active material and the electrolyte is suppressed can be provided. In addition, it is possible to provide a lithium ion storage battery in which the deterioration of the positive electrode active material is suppressed. In addition, it is possible to provide a lithium ion storage battery in which metal deposition on the negative electrode surface is suppressed. In addition, the reaction between the positive electrode active material and the electrolyte can be prevented. It is possible to provide a lithium ion storage battery in which inhibition of the battery reaction caused by the above-mentioned reaction is suppressed. One aspect of the present invention is to manufacture a lithium ion storage battery having good cycle characteristics at high temperatures. In addition, one embodiment of the present invention provides a method for preventing a reaction between a positive electrode active material and an electrolyte solution. To provide a method for producing a lithium ion storage battery in which inhibition of the battery reaction caused by the Another embodiment of the present invention is a novel storage battery, a novel power storage device, or a novel storage battery. It is possible to provide a manufacturing method or a novel method for manufacturing a power storage device.

[0018] The description of these effects does not preclude the existence of other effects. An embodiment does not necessarily have to have all of these effects. Effects other than these may also be included. The above is self-evident from the description, drawings, claims, etc. Other effects can be extracted from the claims and other descriptions. [Brief description of the drawings]

[0019] [Figure 1] 1A to 1C are diagrams illustrating a lithium-ion storage battery of one embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 1 is a diagram illustrating a coin-type storage battery. [Diagram 5] FIG. 1 is a diagram illustrating a cylindrical storage battery. [Figure 6] FIG. 1 is a diagram illustrating a laminated storage battery. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] 1A to 1C are diagrams illustrating a method for manufacturing a storage battery. [Figure 10] FIG. 1 is a diagram illustrating a flexible laminated storage battery. [Figure 11] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 12] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 13] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 14] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 15] 1A and 1B are diagrams illustrating examples of power storage devices. [Figure 16] 1A to 1C are diagrams illustrating application modes of a power storage device. [Figure 17] FIG. 4 is a graph showing cycle characteristics of a storage battery 1 and a comparative storage battery 1. [Figure 18] XPS spectrum of the negative electrode of comparative battery 1. [Figure 19] XPS spectrum of the negative electrode of battery 1. [Figure 20] 4 is a cross-sectional TEM image of the vicinity of the surface of the positive electrode active material of comparative battery 1. [Figure 21] 4 is a cross-sectional TEM image of the vicinity of the surface of the positive electrode active material of the storage battery 1. [Figure 22] FIG. 4 is a diagram showing temperature characteristics of the storage battery 2. [Figure 23] FIG. 1 is a block diagram illustrating one embodiment of the present invention. [Figure 24] FIG. 1 is a conceptual diagram illustrating one embodiment of the present invention. [Diagram 25] FIG. 1 is a circuit diagram illustrating one embodiment of the present invention. [Figure 26] FIG. 1 is a circuit diagram illustrating one embodiment of the present invention. [Figure 27] FIG. 1 is a conceptual diagram illustrating one embodiment of the present invention. [Figure 28] FIG. 1 is a block diagram illustrating one embodiment of the present invention. [Figure 29] 1 is a flowchart illustrating one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, one embodiment of the present invention will be described. However, the present invention can be applied to many different embodiments. The present invention can be implemented in various ways without departing from the spirit and scope of the present invention. It will be readily understood by those skilled in the art that various modifications may be made to the embodiments and details. The present invention is not to be construed as being limited to the description of the embodiments and examples shown.

[0021] The words "membrane" and "layer" may be interchangeable depending on the situation. For example, the term "conductive layer" can be used interchangeably with the term "conductive film." ". Alternatively, for example, the term "insulating film" may be used. It may be possible to change the term to "insulating layer."

[0022] In each of the drawings described in this specification, the positive electrode, the negative electrode, the active material layer, the separator, the exterior body, etc. The size and thickness of each component may be exaggerated for clarity of description. Therefore, each component is not necessarily limited by its size, and the correlation between each component is not necessarily limited by its size. It is not limited to the relative size.

[0023] In addition, in the configuration of one embodiment of the present invention described in this specification, etc., The same reference numerals are used in different drawings for the parts having the same configuration, and the repeated explanations are omitted. In addition, when referring to parts with similar functions, the same hatch pattern is used and symbols are used. In some cases, the number may not be added.

[0024] In addition, the contents of the description of the embodiment of the present invention can be used in appropriate combination. Cut.

[0025] (Embodiment 1) In this embodiment, a lithium-ion storage battery according to one embodiment of the present invention will be described.

[0026] A method for manufacturing a lithium-ion storage battery 110 according to one embodiment of the present invention will be described with reference to FIGS. FIG. 1A is a schematic diagram of a lithium ion battery 110. A lead electrode 107 is drawn out from the exterior body 106. 1 is a schematic cross-sectional view of the lithium ion battery 110, taken along the dashed line B1-B2; 100, a positive electrode active material layer 101, a separator 104, a negative electrode active material layer 103, and a negative electrode collector. The insulating film 102 is stacked on the insulating film 102 and sealed with the electrolyte 105 by the exterior body 106. In addition, the active material layer can be formed on both sides of the current collector, and the storage battery can be formed in a stacked structure. It is also possible to use the same structure.

[0027] <Positive electrode composition> The positive electrode includes a positive electrode active material layer 101 and a positive electrode current collector 100.

[0028] The positive electrode active material used in the positive electrode active material layer 101 is a carrier such as lithium ion. Materials capable of inserting and removing ions can be used, for example, olivine type crystal structures. Examples of such a material include a lithium-containing material having a layered rock salt type crystal structure or a spinel type crystal structure. can be done.

[0029] Lithium-containing materials with an olivine crystal structure (general formula LiMPO4 (M is Fe(II), M Typical examples of n(II), Co(II) or Ni(II)) include LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, LiFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4 (a + b is 1 or less, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO4 (c + d + e is 1 or less, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (f + g + h + i is 1 or less, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc.

[0030] For example, lithium iron phosphate (LiFePO4) is preferable because it well balances the requirements for a cathode active material, such as safety, stability, high capacity density, high potential , the presence of lithium ions that can be extracted during initial oxidation (charging), etc. Item.

[0031] Examples of lithium-containing materials having a layered rock salt-type crystal structure include, for example, lithium cobaltate (LiCoO2), LiNiO2, LiMnO2, Li2MnO3, LiNi 0.8 Co 0.2 O2 and other NiCo-based (general formula is LiNi x Co1-x O2(0 <x<1))、L iNi 0.5 Mn 0.5 O2, etc. NiMn system (general formula: LiNi x Mn 1-x O2(0 <x<1))、LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 NiMnCo system (NMC and The general formula is LiNi x Mn y Co 1-x-y O2(x>0, y>0, x+y<1 In addition, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, Li2 Other examples include MnO3-LiMO2 (M is Co, Ni or Mn).

[0032] In particular, LiCoO2 has a large capacity and is more stable in air than LiNiO2. and is preferable since it has advantages such as being more thermally stable than LiNiO2.

[0033] Examples of lithium-containing materials having a spinel-type crystal structure include LiMn2O4, L i 1+x Mn 2-x O4(0 <x<2)、LiMn 2-x Al x O4(0 <x<2)、L iMn 1.5 Ni 0.5 Examples include O4.

[0034] A lithium-containing material having a spinel-type crystal structure containing manganese, such as LiMn2O4, A small amount of lithium nickel oxide (LiNiO2 or LiNi 1-x M x O2(0 <x<1)(M Mixing Co, Al, etc., suppresses the elution of manganese and the decomposition of the electrolyte. This has the following advantages and is therefore preferable.

[0035] In addition, the positive electrode active material is a compound having the general formula Li (2-j) MSiO4 (M is Fe(II), Mn (II), Co(II), or Ni(II) (j is 0 to 2) The general formula Li (2-j) A typical example of MSiO4 is Li ( 2-j) FeSiO4, Li (2-j) NiSiO4, Li (2-j) CoSiO4, L i (2-j) MnSiO4, Li (2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k Mn l SiO4 (k+l is 1 or less, 0 <k<1、0<l <1), Li (2-j) Fe m Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (m+n+q is 1 or less, 0 <m <1, 0 <n<1、0<q<1)、Li (2-j) Fe r Ni s Co t Mn u SiO4( r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. can be mentioned. and so on.

[0036] Also, as the positive electrode active material, A x M2(XO4)3 (A is Li, Na, or Mg) (M is Fe, Mn, Ti, V, Nb, or Al) (X is S, P, Mo, W, As, or , Si), a NASICON-type compound represented by the general formula can be used. NASICON-type compounds include Fe2(MnO4)3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. and so on. Also, as the positive electrode active material, compounds represented by the general formula Li2MPO4F, Li2MP2O7, Li5M O4 (M is Fe or Mn), perovskite-type fluorides such as MnF3, FeF3, etc., metal chalcogenides (sulfides, selenides , tellurides) such as TiS2, MoS2, lithium-containing materials having an inverse spinel-type crystal structure such as LiMVO4, vanadium oxide-based (V2O5, V6O , LiV3O8, etc.), manganese oxide, organic 13 sulfur, etc. can be used. In addition, when the carrier ion is an alkali metal ion other than lithium ion or an alkaline earth metal ion, in the above compounds and oxides, instead of lithium,

[0037] an alkali metal (for example, sodium, potassium, etc.) or an alkaline earth metal (for example, calcium , strontium, barium, beryllium, magnesium, etc.) can be used. For example, sodium-containing layered oxides such as NaFeO2 and Na [Fe 2 / 3 1 / 2 Mn 1 / 2 O2, etc. can be used as the positive electrode active material.

[0038] ​​ In addition, a material in which a plurality of the above materials are combined may be used as the positive electrode active material. A solid solution of the above materials can be used as the positive electrode active material. Co 1 / 3 Mn 1 / 3 Ni 1 / 3 A solid solution of O2 and Li2MnO3 is used as the positive electrode active material. It is possible.

[0039] The positive electrode active material should preferably have an average primary particle size of 50 nm to 100 μm. .

[0040] The positive electrode active material, together with the negative electrode active material, plays a central role in the battery reaction of the storage battery and is the carrier ion It is a substance that absorbs and releases. In order to extend the life of a storage battery, it is necessary to reduce the irreversible reactions of the battery reaction. It is preferable that the material has a small capacity related to the charge and discharge, and it is preferable that the material has a high charge and discharge efficiency. It is.

[0041] Since the active material comes into contact with the electrolyte, the active material reacts with the electrolyte, causing loss of active material and deterioration. When the capacity of the storage battery decreases, the capacity of the storage battery decreases. It is desirable to prevent such reactions from occurring within the pond, and the effects of suppressing such reactions will be discussed below.

[0042] Acetylene black (AB), graphite particles, and carbon black are used as conductive additives for the electrodes. Carbon nanotubes, graphene, fullerene, etc. can be used.

[0043] The conductive additive can form an electrically conductive network in the electrode. This makes it possible to maintain a path of electrical conduction between the positive electrode active materials. By adding an electric auxiliary agent, it is possible to realize a positive electrode active material layer 101 having high electric conductivity. This can be done.

[0044] In addition to the typical polyvinylidene fluoride (PVDF), polyimide is also used as a binder. , polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene poly styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, Uses polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc. It is possible.

[0045] The content of the binder relative to the total amount of the positive electrode active material layer 101 is 1 wt % or more and 10 wt % or less. is preferable, 2 wt% or more and 8 wt% or less is more preferable, and 3 wt% or more and 5 wt% or less is even more preferable. It is more preferable that the content of the conductive assistant with respect to the total amount of the positive electrode active material layer 101 is 1 wt %. The content is preferably from 1 wt % to 10 wt %, and more preferably from 1 wt % to 5 wt %.

[0046] When the positive electrode active material layer 101 is formed by a coating method, the positive electrode active material, the binder, and the conductive additive are mixed together. The agent and the dispersion medium are mixed to prepare a slurry, which is then applied onto the positive electrode current collector 100 and dried. In this embodiment, a metal material containing aluminum as a main component is used as the positive electrode current collector 100. There are.

[0047] The positive electrode current collector 100 may be made of metals such as stainless steel, gold, platinum, aluminum, titanium, etc. Materials with high electrical conductivity and that do not alloy with carrier ions such as lithium, such as lithium ions and their alloys, are used. In addition, silicon, titanium, neodymium, scandium, molybdenum, etc. Aluminum alloys containing elements that improve heat resistance can be used. Alternatively, the insulating layer 12 may be formed of a metal element that reacts with silicon to form a silicide. Metal elements that form silicides include zirconium, titanium, hafnium, vanadium, and Dium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The positive electrode current collector is available in foil, plate (sheet), mesh, punched metal, and expeller. A shape such as a black metal shape can be appropriately used.

[0048] Through the above steps, a positive electrode for a lithium ion battery can be produced.

[0049] <Negative electrode composition> Next, the negative electrode will be described with reference to FIG. The negative electrode includes a conductive material 102. The process for forming the negative electrode is described below.

[0050] As the negative electrode active material used in the negative electrode active material layer 103, the carbon-based material may be graphite or graphitized carbon. Graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotubes Graphite includes mesocarbon microbeads, graphene, and carbon black. Artificial graphite such as MCMB, coke-based artificial graphite, pitch-based artificial graphite, and spherical natural graphite. Natural graphite such as lead is used. Graphite can be in the form of flakes or spheres. .

[0051] In addition to carbon-based materials, lithium-ion batteries can be used as negative electrode active materials, and can be charged and discharged by alloying and dealloying reactions with lithium. Materials capable of undergoing reactions can also be used. For example, Ga, Si, Al, Ge, Materials containing at least one of Sn, Pb, Sb, Bi, Ag, Zn, Cd, In, etc. These elements have a large capacity compared to carbon, and silicon in particular has a theoretical The capacity is as high as 4200mAh / g, which is preferable. As examples of the alloys based on ZnSn, Mg2Si, Mg2Ge, Mg2Sn, SnS2, V2Sn 3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb , SbSn, etc.

[0052] In addition, the negative electrode active material is SiO, SnO, SnO2, titanium dioxide (TiO2), lithium Li4Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), Niobium pentoxide (Nb2O5), tungsten dioxide (WO2), molybdenum dioxide (Mo O2) can be used.

[0053] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. Li 3-x M x N (M is Co, Ni or Cu) can be used. For example, Li2 .6 Co 0.4 N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) This is preferable.

[0054] When a composite nitride of lithium and transition metals is used, the negative electrode active material contains lithium ions, The positive electrode active material is made of V2O5, Cr3O8, etc., which do not contain lithium ions. Even when a material containing lithium ions is used as the positive electrode active material, By first removing the lithium ions contained in the positive electrode active material, lithium is released as the negative electrode active material. A double nitride of ammonium and a transition metal can be used.

[0055] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. For example, Lithium oxide (LiO), cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. A transition metal oxide that does not undergo an alloying reaction with the negative electrode active material may be used. Further materials in which the reaction occurs include Fe2O3, CuO, Cu2O, RuO2, and Cr2O. 3rd order oxide, CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, G Nitrides such as e3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3 This also occurs with fluorides such as

[0056] For example, the particle size of the negative electrode active material is preferably 50 nm or more and 100 μm or less. .

[0057] In addition, in both the positive electrode active material layer 101 and the negative electrode active material layer 103, a plurality of active materials are used. The materials may be combined in a specific ratio. By using multiple materials in the active material layer, This allows the performance of the active material layer to be selected in more detail.

[0058] Acetylene black (AB), graphite particles, and carbon black are used as conductive additives for the electrodes. Carbon nanotubes, graphene, fullerene, etc. can be used.

[0059] The conductive additive can form an electrically conductive network in the electrode. This makes it possible to maintain a path of electrical conduction between the negative electrode active materials. By adding an electric auxiliary agent, it is possible to realize a negative electrode active material layer 103 having high electric conductivity. This can be done.

[0060] In addition to the typical polyvinylidene fluoride (PVDF), polyimide is also used as a binder. , polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene poly styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, Uses polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc. It is possible.

[0061] The content of the binder relative to the total amount of the negative electrode active material layer 103 is 1 wt % or more and 10 wt % or less. is preferable, 2 wt% or more and 8 wt% or less is more preferable, and 3 wt% or more and 5 wt% or less is even more preferable. It is more preferable that the content of the conductive assistant with respect to the total amount of the negative electrode active material layer 103 is 1 wt %. The content is preferably from 1 wt % to 10 wt %, and more preferably from 1 wt % to 5 wt %.

[0062] A negative electrode active material layer 103 is formed on a negative electrode current collector 102. When forming 3, a negative electrode active material, a binder, a conductive additive, and a dispersion medium are mixed to form a slurry. The coating is applied to the negative electrode current collector 102 and dried. After drying, the coating is pressed if necessary. The theory may also be carried out.

[0063] The negative electrode current collector 102 may be made of any of stainless steel, gold, platinum, zinc, iron, copper, titanium, and tantalum. Metals such as these and their alloys have high electrical conductivity and can be alloyed with carrier ions such as lithium. In addition, metals that react with silicon to form silicides can be used. The metal element that reacts with silicon to form silicide is di- Ru, titanium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum The negative electrode current collector 102 may be in the form of a foil or a plate (seal). Shapes include metal, net, cylinder, coil, punched metal, expanded metal, etc. The negative electrode current collector 102 has a thickness of 5 μm or more and 30 μm or less. It is also advisable to use graphite or the like on a part of the surface of the electrode current collector. A coating layer may be provided.

[0064] Through the above steps, a negative electrode for a lithium ion battery can be produced.

[0065] <Separator configuration> The separator 104 will now be described. The material of the separator 104 may be paper, nonwoven fabric, gas, etc. Lath fiber, nylon (polyamide), vinylon (polyvinyl alcohol fiber) ), polyester, acrylic, polyolefin, polyurethane and other synthetic fibers. However, it is necessary to select a material that does not dissolve in the electrolyte solution described below.

[0066] More specifically, the separator 104 may be made of a material such as a fluorine-based polymer or polyethylene. Polyethers such as ethylene oxide and polypropylene oxide, polyethylene, polypropylene Polyolefins such as ethylene glycol, polyacrylonitrile, polyvinylidene chloride, polymethylmethacrylate acrylate, polymethyl acrylate, polyvinyl alcohol, polymethacrylonitrile, Polyvinyl acetate, polyvinylpyrrolidone, polyethyleneimine, polybutadiene, Polystyrene, polyisoprene, polyurethane polymers and their derivatives, cellulose , paper, nonwoven fabric, glass fiber, either alone or in combination. It is possible.

[0067] The separator 104 has an insulating property to prevent contact between the two electrodes, a property to retain the electrolyte, and a property to conduct ions. As a method for producing a membrane that functions as a separator, There is a method by stretching. For example, a molten polymer material is expanded to release heat, and the resulting film is One method is the stretching pore opening method, in which the membrane is stretched in two axial directions parallel to the membrane to form pores.

[0068] Next, as a method for incorporating the separator 104 into the storage battery, the separator is Alternatively, a separator 104 may be placed on either the positive or negative electrode. Alternatively, it is possible to combine the other of the positive electrode or the negative electrode. The battery can be formed by housing the battery in a housing and impregnating it with an electrolyte.

[0069] The separator 104 is made of a sheet having a size large enough to cover both sides of either the positive electrode or the negative electrode. When the electrode is formed into a tube-like or envelope-like shape and wrapped in a separator 104, the storage During the manufacture of the pond, the electrodes can be protected from mechanical damage and can be easily handled. The electrode wrapped in the separator and the other electrode are placed together in an outer casing and sealed in a container containing an electrolyte. In FIG. 6B, a separator 507 is disposed on the substrate 502. The cross-sectional structure of the storage battery formed in an envelope shape is shown in Figure 6(B). 1 shows a cross-sectional structure of a stacked type storage battery made using multiple sets of the above.

[0070] Furthermore, the separator may be multi-layered. The separator may be formed by the above-mentioned method, The materials of construction and the mechanical strength of the membrane impose limitations on the range of membrane pore size and membrane thickness. The first separator and the second separator are each produced by a stretching method, and then combined. The material constituting the first separator and the second separator can be used in a storage battery. The material may be one or more of the above materials or materials other than those mentioned above. The size of the pores in the film and the volume ratio of the pores (porosity) can be controlled by the forming conditions and the stretching conditions. The thickness and other properties of the film can be determined by the two different characteristics. By using the separator together with the membrane, the separator of the battery is more efficient than when one membrane is used alone. This allows for a wide range of options for the performance of the radar.

[0071] Furthermore, the storage battery may be flexible, and a deformation stress is applied to the flexible storage battery. In this case, the first separator and the second separator slide at the interface between them. Since the stress can be relieved by separating the separators, the structure using multiple separators is It is also suitable as a separator structure for a flexible storage battery.

[0072] Through the above steps, the separator can be assembled into the lithium-ion battery.

[0073] <Electrolyte composition> The electrolyte solution 105 that can be used in the lithium ion battery according to one embodiment of the present invention is an electrolyte. It is preferable to use a non-aqueous solution containing a substance.

[0074] The solvent of the electrolyte 105 is a material in which carrier ions can move. Rotonic organic solvents are preferred, such as ethylene carbonate (EC) and propylene carbonate. (PC), butylene carbonate, chloroethylene carbonate, vinylene carbonate , γ-butyrolactone, γ-valerolactone, dimethyl carbonate (DMC), diethyl Dimethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate ethyl, methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DM E), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, Benzonitrile, tetrahydrofuran, sulfolane, sultone, or any of these Any two or more of these may be used in any combination and ratio.

[0075] In addition, by using a polymer material that can be gelled as a solvent for the electrolyte 105, it is possible to reduce leakage and other problems. This improves safety. It also makes it possible to make lithium-ion batteries thinner and lighter. Representative examples of polymeric materials that can be polymerized are silicone gel, acrylic gel, and acrylonitrile. Polyethylene oxide gel, Polypropylene oxide gel, Fluorine-based gel Examples include polymer gels.

[0076] In addition, ionic liquids (also called room temperature molten salts), which are flame-retardant and difficult to evaporate, are used as the solvent for the electrolyte. ) is used to prevent internal short circuits in lithium-ion batteries and overcharging. Even if the internal temperature rises, the lithium-ion battery can be prevented from exploding or catching fire. This can improve the safety of the lithium-ion storage battery.

[0077] In the battery reaction in the storage battery, the electrolyte reacts with the active material of the positive electrode and When the metals dissolved in the battery are dissolved, the capacity of the battery decreases and the battery deteriorates. When cycle characteristic tests were performed, the capacity decreased significantly with each charge and discharge, resulting in a short-life storage battery. Therefore, in one embodiment of the present invention, the electrolyte material contained in the electrolyte solution has excellent thermal stability. In addition, a material that is inhibited from reacting with the active material is used to inhibit the elution of metal in the active material.

[0078] Examples of the metal in the active material of the positive electrode include Fe, Co, Ni, and Mn. In one embodiment of the present invention, the electrolyte material used in the electrolyte solution is a positive electrode active material layer of these metals. An electrolyte that is suppressed from dissolving from 101 is used. Specifically, in one embodiment of the present invention, The electrolyte that can be used is LiTFSA (lithium bis(trifluoromethanesulfonyl) amide) and LiFSA (lithium bisfluorosulfonylamide). LiTFSA has Li, N, a trifluoromethyl group, and a sulfonyl group. Thus LiTFSA has Li, N, F, S, O, and C. LiFSA has Li, N, F, and a sulfonyl group. SA has Li, N, F, S, and O.

[0079] The electrolyte is LiTFSA (lithium bis(trifluoromethanesulfonyl)amide) or L The electrolyte using iFSA (lithium bisfluorosulfonamide) is hydrolyzed relatively well. It is difficult to cause thermal damage and has excellent thermal stability, so it is effective in preventing the metal in the positive electrode active material from being damaged during the battery reaction in storage batteries. Therefore, the storage battery according to one embodiment of the present invention is repeatedly charged and discharged to suppress the dissolution of the metal. The storage battery is disassembled to remove the negative electrode, and the surface of the negative electrode is analyzed by, for example, XPS (X-ray photoelectron spectroscopy). ) the presence of the metal is not observed or is in extremely small amounts.

[0080] Therefore, in the storage battery according to one embodiment of the present invention, the elution of metal in the positive electrode active material into the electrolyte is suppressed. This suppresses the deterioration of the positive electrode active material and also suppresses the deposition of metal on the negative electrode surface. Therefore, it is possible to provide a storage battery with little capacity degradation and good cycle life.

[0081] In the above electrolyte, the carrier ions are lithium ions. However, carrier ions other than lithium ions can also be used. In the case of alkali metal ions and alkaline earth metal ions, the carrier ions are electrolytic As a substance, in the above lithium salt, an alkali metal (e.g., sodium Alkaline earth metals (e.g., calcium, strontium, barium, etc.) Alternatively, metals such as tungsten, beryllium, or magnesium may be used.

[0082] In addition, the electrolyte used in the storage battery is free of granular waste and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as It is preferable to use a highly purified electrolyte solution with a low content of "impurities." Specifically, the mass ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less, more preferably 1% or less. More preferably, the content of vinylene carbonate in the electrolyte is 0.01% or less. Additives such as ethyl acetate may also be added.

[0083] By using the above-mentioned solvent and the above-mentioned electrolyte, an electrolyte solution for a storage battery according to one embodiment of the present invention is prepared. It is possible.

[0084] LiTFSA (lithium bis(trifluoromethanesulfonyl)amide) or L The electrolyte solution using iFSA (lithium bisfluorosulfonamide) as the electrolyte is When the voltage is high, it may react with the positive electrode current collector, causing the positive electrode current collector to corrode. In order to prevent such corrosion, it is preferable to add a few wt % of LiPF6 to the electrolyte. A passive film is formed on the surface of the positive electrode current collector, and this passive film suppresses the reaction between the electrolyte and the positive electrode current collector. However, in order to maintain cycle characteristics at high temperatures, it is necessary to dissolve the positive electrode active material layer. Therefore, the concentration of LiPF6 is 10 wt% or less, preferably 5 wt% or less, and more preferably It is advisable to keep the content below 3 wt%.

[0085] <Exterior body configuration> Next, the exterior body 106 will be described. The exterior body 106 is made of, for example, polyethylene, polypropylene, etc. Al is applied to a membrane made of propylene, polycarbonate, ionomer, polyamide, etc. A thin metal film made of aluminum, stainless steel, copper, nickel, or other material with excellent flexibility is then applied. On the thin film, an insulating synthetic resin such as polyamide resin or polyester resin is applied as the outer surface of the exterior body. A three-layer film having a membrane can be used. It blocks the permeation of electrolyte and gas, ensures insulation, and is electrolyte-resistant. Fold the exterior body inwards and stack them, or place the two exterior bodies with their inner faces facing each other. By stacking them and applying heat, the material on the inside melts and the two exterior bodies are fused together, forming a seal. A blocking structure can be created.

[0086] If the part where the exterior body is fused or otherwise sealed is the sealed part, the exterior body is folded inward. When the package is folded and folded, a sealing portion is formed at a portion other than the fold, and the first region of the exterior body and The first region and the overlapping second region are fused or otherwise bonded to each other. When the material is kneaded, a sealing portion is formed around the entire outer periphery by a method such as heat fusion.

[0087] When a flexible material is selected from the materials of each member shown in this embodiment, It is possible to create a flexible lithium-ion storage battery. Research and development of flexible batteries for such devices is currently underway. This has created a demand for storage batteries.

[0088] When a storage battery with two sheets of film as the exterior body and electrodes, electrolyte, etc. sandwiched between 1805 is curved The radius of curvature 1802 of the film 1801 on the side closer to the center of curvature 1800 of the battery is The radius of curvature 1804 of the film 1803 on the side farther from the center of curvature 1800 is smaller than that of the film 1803 (FIG. 2( A) If the battery is bent to make the cross section an arc, the surface of the film close to the center of curvature 180° The surface of the film far from the center of curvature 1800 is subjected to compressive stress, and the surface of the film far from the center of curvature 1800 is subjected to tensile stress. This is necessary (Figure 2(B)).

[0089] When a flexible lithium-ion battery is deformed, a large stress is applied to the exterior body. When a pattern consisting of concave or convex parts is formed on the surface of the exterior body, the pressure generated by the deformation of the storage battery is reduced. Even if compressive or tensile stress is applied, the effects of distortion can be suppressed. Therefore, the radius of curvature of the exterior body of the storage battery close to the center of curvature is 30 mm, preferably 10 mm. It can be modified within the range.

[0090] The radius of curvature of a surface will be described with reference to FIG. 3. In FIG. 3(A), a curved surface 1700 is cut. In a cross-sectional plane 1701, a part of a curve 1702 included in a curved surface 1700 is approximated to an arc of a circle. Similarly, the radius of the circle is the radius of curvature 1703, and the center of the circle is the center of curvature 1704. FIG. 3(B) shows a top view of the curved surface 1700. FIG. 3(C) shows the curved surface 1700 in relation to a flat surface 1701. When cutting a curved surface with a plane, the angle of the plane to the curved surface and the cutting The radius of curvature of the curve that appears in the cross section varies depending on the position. The smallest radius of curvature is taken as the radius of curvature of the noodle.

[0091] The cross-sectional shape of the storage battery is not limited to a simple arc shape, and may be a shape that includes a partial arc. For example, the shape shown in FIG. 2(C), a wavy shape (FIG. 2(D)), an S-shape, etc. In the case where the curved surface of the storage battery has a shape having multiple centers of curvature, The two exterior bodies are connected at the surface with the smallest radius of curvature among the curvature radii at each center. The radius of curvature of the exterior body closer to the center of curvature is 30 mm, preferably 10 mm. The battery can be deformed.

[0092] Note that one embodiment of the present invention has been described in this embodiment. An embodiment of the present invention will be described below. However, the embodiment of the present invention is not limited to these. That is, various inventive aspects are described in this and other embodiments. Therefore, one embodiment of the present invention is not limited to a specific embodiment. Although the case of application to a lithium ion battery has been described as an example, one embodiment of the present invention is Various types of batteries, such as lead acid batteries, lithium ion polymer batteries, Nickel-metal hydride battery, nickel-cadmium battery, nickel-iron battery, nickel- It can also be applied to zinc batteries, silver oxide-zinc batteries, solid-state batteries, air batteries, etc. Alternatively, the present invention can be applied to various types of power storage devices, such as primary batteries, capacitors, etc. It is also possible to apply the present invention to a lithium ion capacitor, a lithium ion capacitor, etc. Therefore, or depending on the situation, one embodiment of the present invention may be applied to a lithium ion battery. Alternatively, in one embodiment of the present invention, the electrolyte may contain at least one of LiTFSA and LiFSA. However, one embodiment of the present invention is not limited to this. In some cases, or depending on the situation, in one aspect of the present invention, LiTFSA and LiFSA At least one of the above may be contained in a portion other than the electrolyte solution. Depending on the situation, in one aspect of the invention, the electrolyte may comprise a variety of materials. Or for example, in some cases or depending on the situation, in one aspect of the invention, the electrolyte is Alternatively, the material may include other materials than LiTFSA and LiFSA. Alternatively, or optionally, in one aspect of the invention, the electrolyte is LiTFSA and LiFS A may not be present.

[0093] This embodiment mode can be implemented in appropriate combination with other embodiment modes and examples. be.

[0094] (Embodiment 2) In this embodiment, a structure of a storage battery according to one embodiment of the present invention will be described with reference to FIGS. He explains.

[0095] [Coin-type battery] FIG. 4(A) is an external view of a coin-type (single-layer flat) storage battery, and FIG. 4(B) is a cross-sectional view of the battery. FIG.

[0096] The coin-type storage battery 300 is made up of a positive electrode can 301 that also serves as a positive electrode terminal and a negative electrode can 302 that also serves as a negative electrode terminal. 02 is insulated and sealed by a gasket 303 made of polypropylene or the like. The electrode 304 is composed of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with the positive electrode current collector. The positive electrode active material layer 306 is formed by the above-mentioned. and a conductive assistant to increase the conductivity of the positive electrode active material layer. Good too.

[0097] The negative electrode 307 is composed of a negative electrode current collector 308 and a negative electrode active material layer 309 provided in contact with the negative electrode current collector. The negative electrode active material layer 309 is formed by a negative electrode active material. Binders to increase the conductivity of the negative electrode active material layer, conductive assistants to increase the conductivity of the negative electrode active material layer, etc. A separator 31 may be provided between the positive electrode active material layer 306 and the negative electrode active material layer 309. 0 and an electrolyte (not shown).

[0098] The materials shown in the first embodiment can be used for each component.

[0099] The positive electrode can 301 and the negative electrode can 302 are made of nickel, aluminum, or other materials that are resistant to corrosion by the electrolyte. Metals such as aluminum and titanium, or their alloys or alloys of these with other metals (e.g. stainless steel) In addition, nickel or aluminum can be used to prevent corrosion by the electrolyte. The positive electrode can 301 is the positive electrode 304, and the negative electrode can 302 is the negative electrode. and electrodes 307, respectively.

[0100] The negative electrode 307, the positive electrode 304 and the separator 310 are immersed in an electrolyte, and as shown in FIG. As shown, the positive electrode can 301 is placed downward, and the positive electrode 304, the separator 310, the negative electrode 307, and the negative electrode The cans 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are secured together with a gasket 303 interposed therebetween. The coin-shaped storage battery 300 is manufactured by crimping.

[0101] Here, the flow of current during charging of the storage battery will be explained using FIG. 4(C). When a battery is considered as a closed circuit, the movement of lithium ions and the flow of electric current are in the same direction. In addition, in a lithium-ion battery, the anode (positive electrode) and cathode (negative electrode) are charged and discharged. ) are switched, and the oxidation and reduction reactions are switched, so the redox potential is high. The electrode with the higher reaction potential is called the positive electrode, and the electrode with the lower reaction potential is called the negative electrode. The charging current is constant whether the battery is charging, discharging, or applying a reverse pulse current. Even when a current flows through it, the positive electrode is called the "positive electrode" or "+ electrode (plus electrode)" and the negative electrode is called the " The negative electrode is called the "negative electrode" or "-electrode (minus electrode)". When the terms anode and cathode are used, the reverse occurs during charging and discharging. This can lead to confusion. Therefore, the anode and cathode The term cathode is not used in this specification. When using the term cathode, specify whether it is charging or discharging, and It will also be indicated whether it corresponds to a positive pole or a negative pole.

[0102] The storage battery 400 shown in FIG. 4(C) includes a positive electrode 402, a negative electrode 404, an electrolyte 406, and a separator. The positive terminal 402 and the negative terminal 404 are connected to a charger. As the charging of the storage battery 400 progresses, the potential difference between the electrodes becomes large. In FIG. 4C, current flows from the external terminal of the storage battery 400 to the positive electrode 402, and the stored In the battery 400, the current flows from the positive electrode 402 to the negative electrode 404, and from the negative electrode to the battery 400. The direction of the current flowing towards the external terminal is considered to be positive. In other words, the direction of the charging current is The direction of the current is .

[0103] [Cylindrical storage battery] Next, an example of a cylindrical storage battery will be described with reference to FIG. As shown in FIG. 5(A), the battery has a positive electrode cap (battery lid) 601 on the top surface and The positive electrode cap 601 and the battery can (external can) 602 are disposed on the positive electrode cap 601. It is insulated from 602 by a gasket (insulating packing) 610 .

[0104] FIG. 5(B) is a schematic diagram showing a cross section of a cylindrical storage battery. On the inside of 02, a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 sandwiched between them. Although not shown, the battery element is wound around a center pin. The battery can 602 is closed at one end and open at the other end. Metals such as nickel, aluminum, titanium, etc. that are resistant to corrosion by the electrolyte, or Alloys and alloys of these with other metals (e.g., stainless steel, etc.) can be used. In addition, it is preferable to coat the electrode with nickel, aluminum, etc. to prevent corrosion by the electrolyte. Inside the battery can 602, the battery element in which the positive electrode, the negative electrode, and the separator are wound is The battery element is sandwiched between a pair of insulating plates 608 and 609. The inside of the battery can 602 is filled with a non-aqueous electrolyte (not shown). A storage battery similar to that of the above type can be used.

[0105] The positive electrode 604 and the negative electrode 606 are manufactured in the same manner as the positive electrode and the negative electrode of the coin-type storage battery described above. However, the positive and negative electrodes used in cylindrical storage batteries are wound, so active material is placed on both sides of the current collector. The positive electrode 604 is connected to a positive electrode terminal (positive electrode current collecting lead) 603. The negative electrode 606 is connected to a negative electrode terminal (negative electrode current collecting lead) 607. The positive electrode terminal 603 and the negative electrode terminal 607 can both be made of a metal material such as aluminum. The positive terminal 603 is connected to a safety valve mechanism 612, and the negative terminal 607 is connected to the bottom of the battery can 602. The safety valve mechanism 612 is a PTC (Positive Temperature Coefficient) element. re Coefficient) 611 is electrically connected to the positive electrode cap 601. The safety valve mechanism 612 is a mechanism that releases the positive electrode cap when the internal pressure of the battery exceeds a predetermined threshold. The PTC element 611 cuts off the electrical connection between the positive electrode 601 and the positive electrode 604. is a thermal resistor whose resistance increases when the temperature rises. The PTC element is made of barium titanate (BaTi O3) based semiconductor ceramics, etc. can be used.

[0106] [Laminated type storage battery] Next, an example of a laminated type storage battery will be described with reference to FIG. If the battery is flexible, it has at least a part that is flexible. If implemented in an electronic device, the battery can also be bent to match the deformation of the electronic device.

[0107] The laminated type storage battery 500 shown in FIG. 6(A) includes a positive electrode current collector 501 and a positive electrode active material layer 502, and a negative electrode having a negative electrode current collector 504 and a negative electrode active material layer 505. 506, a separator 507, an electrolyte 508, and an exterior body 509. A separator 507 is provided between a positive electrode 503 and a negative electrode 506 provided in the battery 09. The exterior body 509 is filled with an electrolyte 508. The electrolyte solution shown in embodiment 1 can be used.

[0108] In the laminated storage battery 500 shown in FIG. 6(A), a positive electrode collector 501 and a negative electrode collector The electric current collector 504 also serves as a terminal for electrical contact with the outside. The body 501 and the negative electrode current collector 504 are arranged so as to be partially exposed to the outside from the exterior body 509. In addition, the positive electrode current collector 501 and the negative electrode current collector 504 may be disposed outside the outer casing 509. Instead, a lead electrode is used to connect the lead electrode to the positive electrode current collector 501 or the negative electrode current collector The lead electrode may be exposed to the outside by ultrasonic bonding with the body 504 .

[0109] In the laminated storage battery 500, the exterior body 509 is made of, for example, polyethylene, polypropylene, Al is applied to a membrane made of propylene, polycarbonate, ionomer, polyamide, etc. A thin metal film made of aluminum, stainless steel, copper, nickel, or other material with excellent flexibility is then applied. On the thin film, an insulating synthetic resin such as polyamide resin or polyester resin is applied as the outer surface of the exterior body. A laminate film having a three-layer structure with a membrane can be used.

[0110] FIG. 6B shows an example of a cross-sectional structure of a laminated storage battery 500. For simplicity, an example consisting of two current collectors is shown, but in reality, it is composed of multiple electrode layers. do.

[0111] In FIG. 6B, as an example, the number of electrode layers is 16. In addition, the storage battery 500 has flexibility. In FIG. 6(B), the negative electrode current collector 504 has eight layers and the positive electrode current collector The electrode 501 has eight layers, making a total of 16 layers. The cross section of the negative electrode current collector 504 is shown, in which eight layers are ultrasonically bonded. The number is not limited to 16, and may be more or less. In addition, when the number of electrode layers is small, the battery can be thin. This allows the battery to be molded and has excellent flexibility.

[0112] An example of the external appearance of a laminated storage battery 500 is shown in Figs. 7 and 8. 8 includes a positive electrode 503, a negative electrode 506, a separator 507, an outer casing 509, and a positive electrode lead electrode 51 0 and negative lead electrodes 511.

[0113] 9A shows an external view of a positive electrode 503 and a negative electrode 506. The positive electrode 503 is a positive electrode current collector 501. The positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. The negative electrode 503 has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as the tab region). 06 has a negative electrode current collector 504, and a negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. In addition, the negative electrode 506 has a region where the negative electrode current collector 504 is partially exposed, that is, a tab region. The area and shape of the tab regions of the positive electrode and the negative electrode are not limited to the example shown in FIG. do not have.

[0114] [How to make a laminated battery] Here, an example of a method for manufacturing the laminated type storage battery shown in FIG. 7 will be described with reference to FIG. , (C) will be used to explain.

[0115] First, the negative electrode 506, the separator 507, and the positive electrode 503 are laminated. The negative electrode 506, the separator 507, and the positive electrode 503 are shown. Here, five pairs of negative electrodes and four pairs of positive electrodes are shown. Next, the bonding of the tab regions of the positive electrode 503 and the bonding of the tab region of the positive electrode on the outermost surface are shown. The positive electrode lead electrode 510 is joined to the electrode region 510 by ultrasonic welding or the like. Similarly, the tab regions of the negative electrodes 506 are joined together, and the negative electrode leads to the tab region of the outermost negative electrode are Then, the electrode 511 is bonded.

[0116] Next, the negative electrode 506 , the separator 507 and the positive electrode 503 are placed on the exterior body 509 .

[0117] Next, as shown in FIG. 9(C), the exterior body 509 is folded at the portion indicated by the dashed line. Then, the outer periphery of the exterior body 509 is bonded. For example, thermocompression bonding may be used for bonding. It is connected to a part (or one side) of the exterior body 509 so that the electrolyte 508 can be poured in later. An area where the two are not mixed (hereinafter referred to as an inlet) is provided.

[0118] Next, the electrolyte 508 is introduced into the inside of the exterior body 509 through an inlet provided in the exterior body 509. The electrolyte 508 is preferably introduced under a reduced pressure or an inert gas atmosphere. Finally, the inlet is joined. In this way, a laminated storage battery is formed. It is possible to manufacture a storage battery 500 having such a structure.

[0119] In this embodiment, the storage battery is a coin type, a laminate type, or a cylindrical type. However, other types of batteries, such as sealed batteries and rectangular batteries, can be used. In addition, a structure in which a positive electrode, a negative electrode, and a separator are laminated in multiple layers, The magnetic flux may have a structure in which the magnetic flux is wound.

[0120] The positive electrode active material layer and the electrolyte of the storage battery 300, the storage battery 500, and the storage battery 600 shown in this embodiment The positive electrode active material layer and the electrolyte according to one embodiment of the present invention are used for the storage. The cycle life of the battery 300, the storage battery 500, and the storage battery 600 can be improved.

[0121] FIG. 10 shows an example of mounting a flexible laminated storage battery in an electronic device. As an example of an electronic device to which a flexible power storage device is applied, a television set is Television sets (also called televisions or television receivers), computer monitors, digital digital cameras, digital video cameras, digital photo frames, mobile phones (mobile phones, (also called mobile telephone devices), portable game machines, personal digital assistants, audio playback devices, pachinko machines, etc. Examples include large game consoles.

[0122] In addition, the flexible energy storage device can be mounted on the inner or outer walls of a house or building, or on the inside or outside of a car. It is also possible to incorporate it along the curved surfaces of the interior or exterior of the vehicle.

[0123] FIG. 10A shows an example of a mobile phone. A mobile phone 7400 includes a housing 7401. In addition to the display unit 7402, operation buttons 7403, an external connection port 7404, The mobile phone 7400 is equipped with a speaker 7405, a microphone 7406, and the like. It has device 7407.

[0124] FIG. 10B shows the mobile phone 7400 in a curved state. When the 0 is deformed by an external force and curved as a whole, the storage device installed inside The bent power storage device 7407 is also bent. The power storage device 7407 is a laminated storage battery.

[0125] FIG. 10D shows an example of a bangle-type display device. The portable display device 7100 is The device includes a housing 7101 , a display portion 7102 , operation buttons 7103 , and a power storage device 7104 . FIG. 10E shows a bent state of the power storage device 7104.

[0126] [Structural example of power storage device] Structural examples of the power storage device will be described with reference to FIGS.

[0127] 11A and 11B are diagrams showing the external appearance of a power storage device. The device includes a substrate 900 and a storage battery 913. A label 910 is attached to the storage battery 913. As shown in FIG. 11B, the power storage device includes a terminal 951 and a terminal 952. It has an antenna 914 and an antenna 915.

[0128] The circuit board 900 includes a terminal 911 and a circuit 912. The terminal 911 is connected to a terminal 951. , a terminal 952, an antenna 914, an antenna 915, and a circuit 912. A plurality of terminals 911 are provided, and each of the plurality of terminals 911 is used as a control signal input terminal, a power supply terminal, etc. may also be used.

[0129] The circuit 912 may be provided on the back surface of the circuit board 900. The antenna 915 is not limited to a coil shape, but may be, for example, a wire shape or a plate shape. Planar antenna, aperture antenna, traveling wave antenna, EH antenna, magnetic field antenna, dielectric Alternatively, antenna 914 or antenna 915 may be used. The flat conductor may function as one of the conductors for electric field coupling. In other words, the annulus can be used as one of the two conductors of the capacitor. In this way, the electromagnetic field, the magnetic field, and the like can be detected by the antenna 914 or the antenna 915. Alternatively, power can be exchanged using an electric field.

[0130] The line width of antenna 914 is preferably larger than the line width of antenna 915. This allows the amount of power received by the antenna 914 to be increased.

[0131] The power storage device has a layer 916 between the antenna 914 and the antenna 915 and the storage battery 913. The layer 916 has a function of preventing the influence of the storage battery 913 on the electromagnetic field, for example. The layer 916 may be made of, for example, a magnetic material.

[0132] The structure of the power storage device is not limited to that shown in FIG.

[0133] For example, as shown in FIG. 12(A-1) and FIG. 12(A-2), In the storage battery 913 shown in (B), an antenna may be provided on each of a pair of opposing surfaces. FIG. 12(A-1) is an external view seen from one side of the pair of faces. 11(A) and 11(B) are external views of the pair of surfaces as viewed from the other side. 11(A) and 11(B) are the same as those in the power storage device shown in FIG. The description of the power storage device can be used as appropriate.

[0134] As shown in FIG. 12(A-1), a layer 916 is sandwiched between one of a pair of surfaces of a storage battery 913. 12(A-2), a retainer 914 is provided on the other of the pair of surfaces of the storage battery 913. The layer 917 is provided with an antenna 915 sandwiched between the layers 917. The layer 917 is, for example, a storage battery 913. The layer 917 has a function of preventing the influence of the electromagnetic field generated by the magnetic field. You can use your body.

[0135] By adopting the above structure, the size of both the antenna 914 and the antenna 915 can be increased. It is possible.

[0136] 12(B-1) and 12(B-2), In the storage battery 913 shown in FIG. 9B, a separate antenna may be provided on each of a pair of opposing faces. FIG. 12(B-1) is an external view seen from one side of the pair of faces. FIG. 11(A) and FIG. 11(B) are external views seen from the other side of the pair of surfaces. The same parts as those in the power storage device shown in FIG. 11B are shown in FIG. The description of the power storage device can be used as appropriate.

[0137] As shown in FIG. 12(B-1), a layer 916 is sandwiched between one of a pair of surfaces of a storage battery 913. 12(B-2), a storage battery 91 An antenna 918 is provided on the other of the pair of surfaces of the substrate 3 with a layer 917 interposed therebetween. The antenna 918 is For example, the antenna 918 has a function of performing data communication with an external device. For example, an antenna having a shape applicable to antenna 914 and antenna 915 may be applied. As a method for communication between the power storage device and other devices via the antenna 918, NFC is used. It is possible to apply a response method that can be used between the power storage device and other devices, such as the above. Cut.

[0138] 13(A), the storage battery 913 shown in FIG. 11(A) and FIG. 11(B) A display device 920 may be provided. The display device 920 is connected to the terminal 911 via the terminal 919. The label 910 is not provided on the portion where the display device 920 is provided. Note that the same parts as those in the power storage device shown in FIG. The description of the power storage device in FIGS. 11(A) and 11(B) can be used as appropriate.

[0139] The display device 920 displays, for example, an image indicating whether charging is in progress, an image indicating the amount of stored power, etc. The display device 920 may be, for example, an electronic paper, a liquid crystal display device, an electrophotographic display device, or the like. For example, an electroluminescence (EL) display device can be used. By using the par, the power consumption of the display device 920 can be reduced.

[0140] 13B, the storage battery 913 shown in FIG. 11A and FIG. 11B may be A sensor 921 may be provided. The sensor 921 is electrically connected to the terminal 911 via a terminal 922. Note that the same parts as those of the power storage device shown in FIG. The description of the power storage device in FIGS. 11A and 11B can be used as appropriate.

[0141] The sensor 921 may be, for example, a sensor for detecting displacement, position, speed, acceleration, angular velocity, number of rotations, distance, light, etc. , liquid, magnetic, temperature, chemical, sound, time, hardness, electric field, current, voltage, power, radiation, flow It is sufficient if the device has the function of measuring the amount, humidity, gradient, vibration, odor, or infrared rays. By providing the sensor 921, for example, data indicating the environment in which the power storage device is placed can be obtained. It is also possible to detect a signal (such as temperature) and store it in memory within the circuit 912.

[0142] Further, a structural example of the storage battery 913 will be described with reference to FIGS.

[0143] The storage battery 913 shown in FIG. 14A is provided with a terminal 951 and a terminal 952 inside a housing 930. The winding body 950 is impregnated with an electrolyte inside the housing 930. The terminal 952 is in contact with the housing 930, and the terminal 951 is in contact with the housing by using an insulating material or the like. 14A, the housing 930 is not in contact with the housing 930. For convenience, the housing 930 is shown in a detached state in FIG. However, in reality, the winding body 950 is covered by the housing 930, and the terminals 951 and 952 are extends outside the housing 930. The housing 930 is made of a metal material (e.g., aluminum). etc.) or a resin material can be used.

[0144] As shown in FIG. 14B, the housing 930 shown in FIG. 14A is made of a plurality of materials. For example, the storage battery 913 shown in FIG. 14B may be formed by a housing 930a and a housing 93 930b are attached to each other, and a wound body 95 is disposed in the area surrounded by the housings 930a and 930b. 0 is provided.

[0145] The housing 930a can be made of an insulating material such as an organic resin. By using materials such as organic resin on the surface on which the electric field is formed, the electric field shielding by the storage battery 913 is If the electric field shielding by the housing 930a is small, the inside of the housing 930a can be suppressed. Antennas such as antenna 914 and antenna 915 may be provided in the housing 930b. For example, a metal material can be used.

[0146] The structure of the wound body 950 is shown in FIG. The winding body 950 has a pole 932 and a separator 933. The negative electrode 931 and the positive electrode 932 are stacked on top of each other, and the laminated sheet is wound to form a wound body. The negative electrode 931, the positive electrode 932, and the separator 933 are laminated together. You can stack several of them.

[0147] The negative electrode 931 is connected to the terminal 911 shown in FIG. 11 via one of the terminals 951 and 952. The positive electrode 932 is connected to the terminal 91 shown in FIG. Connected to 1.

[0148] [Example of electrical equipment: Installed in a vehicle] Next, an example of installing a storage battery in a vehicle will be shown. Hybrid electric vehicles (HEV), electric vehicles (EV), plug-in hybrid vehicles (PHEV), etc. This will make the next generation of clean energy vehicles a reality.

[0149] FIG. 16 shows an example of a vehicle using one embodiment of the present invention. 100 is an electric vehicle that uses an electric motor as a power source for running; or A hybrid vehicle that can select between an electric motor and an engine as a power source for driving. By using one embodiment of the present invention, the vehicle can be repeatedly charged and discharged. In addition, the automobile 8100 includes a power storage device. In addition to driving the electric motor, it also drives the headlights 8101 and interior lights (not shown). ) can be used to provide power to light-emitting devices such as LEDs.

[0150] In addition, the power storage device may be used for displaying information such as a speedometer and a tachometer of the automobile 8100. The power storage device can supply power to the navigation device of the automobile 8100. The present invention can provide power to semiconductor devices such as power distribution systems.

[0151] The automobile 8200 shown in FIG. 16B is a power storage device of the automobile 8200. The device can be charged by receiving power from an external charging facility using a contactless charging method or other methods. FIG. 16B shows a diagram of a charging device 8021 installed on the ground and a storage device 8200 installed in the vehicle. The charging device is shown being charged via a cable 8022. The power supply method and connector standards are specified as appropriate, such as CHAdeMO (registered trademark) or Combo. The charging device 8021 may be a charging station provided in a commercial facility. For example, plug-in technology allows the The battery storage device installed in the vehicle 8200 can be charged by the AC / DC converter. This can be achieved by converting AC power into DC power via a conversion device such as an inverter.

[0152] Although not shown, a power receiving device is mounted on the vehicle and receives power from a ground power transmitting device in a non-contact manner. In this non-contact power supply method, a power transmission device is installed on the road or exterior wall. By incorporating this technology, charging can be done not only when the vehicle is stopped but also while it is moving. Using this method, electric power may be transmitted between vehicles. A solar cell may be provided to charge the power storage device while the vehicle is stopped or running. The power can be supplied using an electromagnetic induction method or a magnetic resonance method.

[0153] According to one embodiment of the present invention, the cycle characteristics of a power storage device can be improved and the reliability can be improved. Furthermore, according to one embodiment of the present invention, the characteristics of a power storage device can be improved. Therefore, the electric storage device itself can be made smaller and lighter. This contributes to reducing the weight of the vehicle, improving the cruising distance. The power storage device can be used as a power supply source for other purposes besides vehicles. It is possible to avoid using commercial power during peak hours.

[0154] This embodiment mode can be implemented in appropriate combination with other embodiment modes and examples. be.

[0155] In this specification, etc., in a drawing or text described in a certain embodiment, When at least one specific example is described, it is not possible to derive a generic concept of that specific example. It will be easily understood by those skilled in the art. When at least one specific example is described in a figure or text, the general outline of that specific example is The invention is also disclosed as an embodiment of the invention and may constitute an embodiment of the invention. And one aspect of the invention can be said to be clear.

[0156] In this specification, at least the contents shown in the drawings (or even a part of the drawings) This is disclosed as one aspect of the invention and can constitute one aspect of the invention. Therefore, if something is shown in a diagram, it does not need to be explained in words. However, the contents are disclosed as one aspect of the invention and constitute one aspect of the invention. Similarly, a part of the drawings may be regarded as an embodiment of the invention. This is disclosed as one embodiment of the present invention. It can be said that one aspect of the invention is clear.

[0157] (Embodiment 3) A battery control device that can be used in combination with a battery cell containing the material described in the above embodiment. A battery management unit (BMU) and the battery For transistors suitable for the circuits constituting the control unit, refer to Figs. 23 to 29. In this embodiment, a battery of a power storage device having battery cells connected in series will be described. The control unit will now be described.

[0158] When multiple battery cells connected in series are repeatedly charged and discharged, In this case, variations in charge / discharge characteristics occur, and the capacity (output voltage) of each battery cell differs. In a series-connected battery cell, the total capacity during discharge is proportional to the capacity of the battery cell with the smallest capacity. If there is variation in the capacity of each battery cell, the overall capacity during discharge will be smaller. If charging is performed based on the battery cell with the smallest capacity, there is a risk of insufficient charging. If charging is performed based on the battery cell with the larger capacity, there is a risk of overcharging.

[0159] Therefore, the battery control unit of the power storage device having battery cells connected in series is It has the function of aligning the capacity variation between battery cells, which can cause overcharging. The circuit configuration for aligning the capacitance variation between the resistors, capacitors, or inductors can be used. There are other methods such as the transistor method, but here we use a transistor with a small off-current to reduce the variation in capacitance. An example of a circuit configuration that can be made uniform will be described below.

[0160] As a transistor with low off-state current, a transistor having an oxide semiconductor in a channel formation region is An OS transistor with a small off-state current is preferred. By using it in the circuit configuration of the battery control unit of the device, the amount of charge leaking from the battery is reduced, This makes it possible to suppress the decrease in capacity over time.

[0161] The oxide semiconductor used in the channel formation region is In-M-Zn oxide (M is Ga, Sn, Y, Zr, La, Ce, or Nd) is used to form an oxide semiconductor film. In the target, if the atomic ratio of metal elements is In:M:Zn=x1:y1:z1, 、 x1 / y1 is 1 / 3 or more and 6 or less, and further 1 or more and 6 or less, and z1 / y1 is 1 It is preferable that z1 / y1 is 1 or more and 6 or less, and more preferably 1 or more and 6 or less. When the content is 6 or less, a CAAC-OS film is easily formed as the oxide semiconductor film.

[0162] Here, the CAAC-OS film will be described.

[0163] The CAAC-OS film is one of oxide semiconductor films having a plurality of crystal parts aligned along the c-axis.

[0164] Transmission Electron Microscope (TEM) A bright-field image and a combined diffraction pattern of the CAAC-OS film were obtained by using a microscope. By observing the TEM image, multiple crystalline regions can be confirmed. On the other hand, the high-resolution TEM image also shows clear boundaries between crystals, i.e. grain boundaries. Therefore, the CAAC-OS film is It can be said that the decrease in electron mobility caused by grain boundaries is unlikely to occur.

[0165] When a high-resolution TEM image of the cross section of the CAAC-OS film was observed from a direction approximately parallel to the sample surface, It can be seen that the metal atoms are arranged in layers in the crystal part. Each layer of metal atoms is The CAAC-OS film is formed on the surface (also called the surface on which the film is formed) or on the upper surface. The CAAC-OS film has a shape similar to that of the crystalline silicon film, and is aligned parallel to the surface on which the CAAC-OS film is formed or the upper surface.

[0166] On the other hand, a high-resolution TEM image of the plane of the CAAC-OS film was observed from a direction approximately perpendicular to the sample surface. It was confirmed that the metal atoms in the crystals were arranged in triangular or hexagonal shapes. However, there is no regularity in the arrangement of metal atoms between different crystal parts.

[0167] X-ray diffraction (XRD) was performed on the CAAC-OS film. For example, a CAAC-OS film with InGaZnO4 crystals was In the out-of-plane analysis, a peak was observed at a diffraction angle (2θ) of approximately 31°. This peak is attributed to the (009) plane of the InGaZnO4 crystal. From this, it can be seen that the crystals of the CAAC-OS film have a c-axis orientation, and the c-axis is approximately aligned on the surface on which the film is formed or on the upper surface. You can see that it is oriented vertically.

[0168] In addition, the out-of-plane method of CAAC-OS film with InGaZnO4 crystals In the analysis by , in addition to the peak at 2θ near 31°, a peak also appeared at 2θ near 36°. The peak at 2θ of around 36° may be due to the c-axis orientation in some parts of the CAAC-OS film. The CAAC-OS film contains crystals that do not have a 2θ of around 31°. It is preferred that the spectrum exhibits a peak and does not exhibit a peak at 2θ of around 36°.

[0169] The CAAC-OS film is an oxide semiconductor film with a low concentration of impurities. The impurities are hydrogen, carbon, and The elements are other than the main components of the oxide semiconductor film, such as silicon and transition metal elements. The elements that bond to oxygen more strongly than the metal elements that form the oxide semiconductor film, such as arsenic, are oxidized. By removing oxygen from the oxide semiconductor film, the atomic arrangement of the oxide semiconductor film is disrupted, reducing its crystallinity. In addition, heavy metals such as iron and nickel, argon, and carbon dioxide have an atomic radius of Since the molecular radius is large, when the cation is contained in the oxide semiconductor film, the The impurities in the oxide semiconductor film may cause the atomic arrangement to be disturbed, which may result in a decrease in crystallinity. Objects can act as carrier traps or carrier generation sources.

[0170] The CAAC-OS film is an oxide semiconductor film having a low density of defect states. Oxygen vacancies in the semiconductor film can become carrier traps or trap hydrogen, It can be a carrier source.

[0171] A material with a low impurity concentration and a low defect level density (few oxygen vacancies) is called a high-purity intrinsic or The term "substantially high-purity intrinsic" refers to a highly-purified intrinsic oxide semiconductor film. Since there are fewer carrier generation sources, the carrier density can be reduced. The transistor including the oxide semiconductor film has electrical characteristics in which the threshold voltage is negative ( Also called normally-on.) In addition, high purity intrinsic or substantially high purity The highly intrinsic oxide semiconductor film has few carrier traps. The transistors using the thin film have small fluctuations in electrical characteristics and are highly reliable. Note that it takes a certain time for charges trapped in the carrier traps in the oxide semiconductor film to be released. The time when the charge is released is long, and it may behave as if it is a fixed charge. A transistor using an oxide semiconductor film having a high density of defect states has unstable electrical characteristics. This may be the case.

[0172] In addition, the electrical characteristics of transistors using CAAC-OS films were improved by irradiation with visible light or ultraviolet light. The fluctuation is small.

[0173] Note that an OS transistor is a transistor having silicon in a channel formation region (a Si transistor). Since the band gap is larger than that of a conventional transistor, dielectric breakdown does not occur when a high voltage is applied. When battery cells are connected in series, a voltage of several hundred volts is generated, but The circuit configuration of the battery control unit applied to such a battery cell in the battery device includes the above-mentioned It is suitable to configure the semiconductor device using an OS transistor having the above structure.

[0174] FIG. 23 shows an example of a block diagram of a power storage device. A terminal pair BT01, a terminal pair BT02, a switching control circuit BT03, and a switching circuit BT0 4, a switching circuit BT05, a transformer control circuit BT06, and a transformer circuit BT07, and a battery unit BT08 including a plurality of connected battery cells BT09.

[0175] In addition, in the power storage device BT00 of FIG. 23, the terminal pair BT01 and the terminal pair BT02 are A switching control circuit BT03, a switching circuit BT04, a switching circuit BT05, and a transformer control The part consisting of the circuit BT06 and the transformer circuit BT07 is called the battery control unit. It is possible.

[0176] The switching control circuit BT03 controls the operation of the switching circuits BT04 and BT05. Specifically, the switching control circuit BT03 controls the measured voltage of each battery cell BT09. Based on the voltage, the battery cells to be discharged (discharging battery cell group) and the battery cells to be charged (charging battery cell group) are selected. Determine the number of cells (pond cell group).

[0177] Furthermore, the switching control circuit BT03 controls the determined discharge battery cell group and charge battery cell group. Based on the group, the control signal S1 and the control signal S2 are output. This control signal S1 connects the terminal pair BT01 and the discharge battery cell group. The control signal S2 is a signal that controls the switching circuit BT04 so as to connect the This control signal S2 is output to the switching circuit BT05. This is a signal that controls the switching circuit BT05 to connect the group.

[0178] The switching control circuit BT03 includes switching circuits BT04, BT05, and Considering the configuration of the transformer circuit BT07, between the terminal pair BT01 and the discharge battery cell group, or between the terminal Control is performed so that terminals of the same polarity are connected between the child pair BT02 and the charging battery cell group. It generates a signal S1 and a control signal S2.

[0179] The operation of the switching control circuit BT03 will now be described in detail.

[0180] First, the switching control circuit BT03 measures the voltage of each of the multiple battery cells BT09. The switching control circuit BT03 then selects, for example, the battery cell BT09 having a voltage equal to or higher than a predetermined threshold. High voltage battery cells (high voltage cells), battery cells BT09 with voltages below a certain threshold are classified as low voltage It is determined to be a battery cell (low voltage cell).

[0181] There are various methods for determining whether a cell is a high-voltage cell or a low-voltage cell. For example, the switching control circuit BT03 selects the most highly charged battery cell BT09 from among multiple battery cells. The voltage of each battery cell BT0 is set based on the voltage of the battery cell BT09 with the highest or lowest voltage. 9 may be determined to be a high-voltage cell or a low-voltage cell. In this case, the switching control circuit BT03 determines whether the voltage of each battery cell BT09 is equal to or greater than a predetermined ratio of the reference voltage. By doing so, it is possible to determine whether each battery cell BT09 is a high-voltage cell or a low-voltage cell. Then, the switching control circuit BT03 switches between the discharging battery cell group and the charging battery cell group based on the result of this judgment. The pond cell group is determined.

[0182] In addition, among the multiple battery cells BT09, high voltage cells and low voltage cells are mixed in various states. For example, the switching control circuit BT03 can select the voltage between high-voltage cells and low-voltage cells. The part with the largest number of high-voltage cells connected in series is the discharge battery cell group. The switching control circuit BT03 charges the part with the most low-voltage cells connected in series. The switching control circuit BT03 detects battery cells that are close to being overcharged or overdischarged. Even if the battery cell BT09 is preferentially selected as the discharge battery cell group or the charge battery cell group, good.

[0183] An example of the operation of the switching control circuit BT03 in this embodiment will now be described with reference to FIG. FIG. 24 is a diagram for explaining an example of the operation of the switching control circuit BT03. For convenience of explanation, FIG. 24 shows an example in which four battery cells BT09 are connected in series. explain.

[0184] First, in the example of FIG. 24(A), if the voltages of the battery cells a to d are voltages Va to Vd, then In other words, the relationship of Va=Vb=Vc>Vd is satisfied when three consecutive high voltages The high-voltage cells a to c and one low-voltage cell d are connected in series. The 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 the charging battery cell group. .

[0185] Next, the example of FIG. 24B shows a case where the relationship is Vc>Va=Vb>>Vd. That is, between two consecutive low voltage cells a and b, one high voltage cell c, and one over-discharge The nearby low-voltage cell d is connected in series. In this case, the switching control circuit BT03 The high-voltage cell c is determined as the discharge battery cell group. Since the low-voltage cell d is close to being over-discharged, it is not the two consecutive low-voltage cells a and b that are The charging cell d is preferentially determined as the charging battery cell group.

[0186] Finally, the example of FIG. 24(C) shows a case where the relationship Va>Vb=Vc=Vd holds. 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 the discharge battery cell group. The switching control circuit BT03 also controls the charging of three consecutive low-voltage cells b to d. Determined as a battery cell group.

[0187] The switching control circuit BT03 determines the results as shown in the examples of FIGS. Based on this, information indicating the discharge battery cell group to which the switching circuit BT04 is connected is set. The control signal S1 and information indicating the charging battery cell group to which the switching circuit BT05 is connected are set. The control signal S2 thus determined is sent to the switching circuit BT04 and the switching circuit BT05. Each is output.

[0188] The above is a detailed explanation of the operation of the switching control circuit BT03.

[0189] The switching circuit BT04 is in response to a control signal S1 output from the switching control circuit BT03. The connection destination of the terminal pair BT01 is the discharge battery cell determined by the switching control circuit BT03. Set the rule group.

[0190] The terminal pair BT01 is composed of a pair of terminals A1 and A2. Either one of the terminals A1 and A2 is connected to the most upstream (high voltage) of the discharge battery cell group. The other terminal is connected to the positive terminal of the battery cell BT09 located at the lowest position in the discharge battery cell group. By connecting it to the negative terminal of the battery cell BT09 located downstream (low potential side), The switch circuit BT04 is set to the control signal S1. The obtained information can be used to identify the position of the discharging battery cell group.

[0191] The switching circuit BT05 is in response to a control signal S2 output from the switching control circuit BT03. The connection destination of the terminal pair BT02 is determined by the switching control circuit BT03. Set the rule group.

[0192] The terminal pair BT02 is composed of a pair of terminals B1 and B2. Either of these terminals B1 and B2 is connected to the most upstream (high voltage) of the charging battery cell group. The other terminal is connected to the positive terminal of the battery cell BT09 located at the By connecting it to the negative terminal of the battery cell BT09 located downstream (low potential side), The switch circuit BT05 is set to the control signal S2. The position of the rechargeable battery cell group can be recognized using the obtained information.

[0193] FIG. 25 and FIG. 2 are circuit diagrams showing configuration examples of the switching circuits BT04 and BT05. Shown in 6.

[0194] In FIG. 25, the switching circuit BT04 includes a plurality of transistors BT10 and a bus BT11 and The bus BT11 is connected to the terminal A1. 2 is connected to the terminal A2. One of them is alternately connected to the buses BT11 and BT12. The other of the sources or drains of the multiple transistors BT10 is connected to two adjacent It is connected between battery cells BT09.

[0195] Among the multiple transistors BT10, the transistor BT10 located at the most upstream The other of the source and drain is the positive electrode of the battery cell BT09 located at the most upstream of the battery unit BT08. The transistor BT10 located at the most downstream side is connected to the terminal. The other of the source and drain of the transistor BT10 is located at the most downstream of the battery unit BT08. It is connected to the negative terminal of battery cell BT09.

[0196] The switching circuit BT04 is configured to control a control signal S1 to be applied to the gates of a plurality of transistors BT10. In response, one of the plurality of transistors BT10 connected to the bus BT11 and the bus B and one of the plurality of transistors BT10 connected to T12 are respectively brought into a conductive state. This connects the discharge battery cell group to the terminal pair BT01. The positive terminal of the battery cell BT09, which is located most upstream in the battery group, is connected to the terminal A1 or A 2. Also, the battery cell located most downstream in the discharge battery cell group is connected to either The negative terminal of the BT09 terminal is the other of the terminals A1 or A2 of the terminal pair, i.e., the positive terminal The terminal that is not connected to the

[0197] It is preferable to use an OS transistor for the transistor BT10. Since the off-state current of the capacitor is small, the amount of charge leaking from the battery cells that do not belong to the discharge battery cell group is reduced. This suppresses the decrease in capacitance over time. Dielectric breakdown is unlikely to occur when voltage is applied. Therefore, the output voltage of the discharge battery cell group is large. However, the transistor BT10 that is in a non-conducting state is connected to the battery cell BT09 and the terminal pair It is possible to insulate the BT01.

[0198] In addition, in FIG. 25, the switching circuit BT05 includes a plurality of transistors BT13 and a current control The bus BT15 and the bus BT16 are connected to the switch BT14 and the bus BT16. 16 is disposed between the plurality of transistors BT13 and the current control switch BT14. The sources or drains of the multiple transistors BT13 are alternately The transistors BT13 are connected to buses BT15 and BT16. The other of the source and drain is connected between two adjacent battery cells BT09. is.

[0199] Among the multiple transistors BT13, the transistor BT13 located at the most upstream The other of the source and drain is the positive electrode of the battery cell BT09 located at the most upstream of the battery unit BT08. The transistor BT13 located at the most downstream side is connected to the terminal. The other of the source and drain of the transistor BT13 is located at the most downstream of the battery unit BT08. It is connected to the negative terminal of battery cell BT09.

[0200] The transistor BT13 is an OS transistor, similar to the transistor BT10. Since the off-state current of the OS transistor is small, it is preferable that the OS transistor does not belong to the rechargeable battery cell group. This reduces the amount of charge leaking from the battery cell and suppresses the decrease in capacity over time. In addition, OS transistors are less susceptible to dielectric breakdown when high voltages are applied. A transistor BT that is in a non-conducting state even if the voltage for charging the battery cell group is large. 13 can be electrically insulated from the battery cell BT09 to which the terminal pair BT02 is connected.

[0201] The current control switch BT14 includes a switch pair BT17 and a switch pair BT18. One end of the switch pair BT17 is connected to the terminal B1. The end is split into two switches, one of which is connected to bus BT15 and the other The 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 into two switches, while The switch is connected to bus BT15, and the other switch is connected to bus BT16. .

[0202] The switches in the switch pairs BT17 and BT18 are transistors BT10 Similarly to the transistor BT13, an OS transistor is preferably used.

[0203] The switching circuit BT05 switches the transistor BT13 and the current control By controlling the combination of on / off states of the switch BT14, and terminal pair BT02.

[0204] As an example, the switching circuit BT05 is configured to switch the charging battery cell group and the terminal pair BT0 as follows: Connect 2.

[0205] The switching circuit BT05 is configured to control a control signal S2 to be applied to the gates of a plurality of transistors BT13. In response, the positive terminal of the battery cell BT09 located most upstream in the charging battery cell group is connected. The switching circuit BT05 turns on the transistor BT13 that is connected to the In response to a control signal S2 applied to the gate of the transistor BT13, Transistor BT13 connected to the negative terminal of the most downstream battery cell BT09 is put into a conductive state.

[0206] The polarity of the voltage applied to terminal pair BT02 is the same as that of the discharge battery cell group connected to terminal pair BT01. The method of charging the rechargeable battery cell group may vary depending on the configuration of the transformer circuit BT07. To allow current to flow in the same direction, terminals of the same polarity must be connected between terminal pair BT02 and the charging battery cells. Therefore, the current control switch BT14 is controlled by the control signal S2 as follows: Depending on the polarity of the voltage applied to the terminal pair BT02, the switch pair BT17 and the switch pair BT It is controlled to switch between each of the 18 connection destinations.

[0207] As an example, a voltage is applied to the terminal pair BT02 such that the terminal B1 is positive and the terminal B2 is negative. In this case, the most downstream battery cell BT09 of the battery unit BT08 When the battery cell group is a charging battery cell group, the switch pair BT17 is turned on / off by the control signal S2. That is, the switch pair BT17 is controlled to be connected to the positive terminal of the switch pair BT09. The switch connected to the bus BT16 is turned on, and the bus BT1 of the switch pair BT17 is turned on. On the other hand, the switch pair BT18 is in the OFF state when the control signal S2 In other words, the switch is controlled so as to be connected to the negative terminal of the battery cell BT09. The switch connected to the bus BT15 of the switch pair BT18 is turned on, The switch connected to the bus BT16 of the terminal pair T18 is turned off. Between the BT02 and the charging battery cell group, terminals with the same polarity are connected. The direction of the current flowing from the BT02 pair is controlled so that it charges the battery cell group. will be done.

[0208] In addition, the current control switch BT14 is not the switching circuit BT05 but the switching circuit BT In this case, the current control switch BT14 is By controlling the polarity of the voltage applied to the terminal pair BT01, the voltage applied to the terminal pair BT02 can be The current control switch BT14 controls the polarity of the voltage applied to the terminal pair BT02. This controls the direction of current flowing from the charger to the battery cell group.

[0209] FIG. 26 shows a configuration example of the switching circuit BT04 and the switching circuit BT05, which is different from that shown in FIG. FIG.

[0210] In FIG. 26, the switching circuit BT04 includes a plurality of transistor pairs BT21 and a bus BT24. The bus BT24 is connected to the terminal A1. BT25 is connected to the terminal A2. Each of them is branched by the transistor BT22 and the transistor BT23. Either the source or the drain of the BT22 is connected to the bus BT24. Either the source or the drain of the transistor BT23 is connected to the bus BT25. The other ends of the transistor pairs BT21 are connected between two adjacent battery cells BT09. Among the multiple transistor pairs BT21, the transistor located at the most upstream The other end of the transistor pair BT21 is connected to the positive terminal of the battery cell BT09 located at the most upstream of the battery section BT08. Also, among the multiple transistor pairs BT21, the one located at the most downstream The other end of the transistor pair BT21 is connected to the battery cell BT0 located at the most downstream of the battery section BT08. 9 is connected to the negative terminal.

[0211] The switching circuit BT04 switches between the transistor BT22 and the transistor BT31 in response to the control signal S1. By switching the conductive / non-conductive state of BT23, the connection of the transistor pair BT21 is The connection destination is switched to either terminal A1 or terminal A2. If T22 is conductive, transistor BT23 is non-conductive and is connected to terminal On the other hand, if the transistor BT23 is in a conductive state, the transistor BT22 The transistors BT22 and BT23 are non-conductive and connected to the terminal A2. Which of the transistors BT23 is turned on is determined by a control signal S1.

[0212] Two transistor pairs BT21 are used to connect the terminal pair BT01 to the discharge battery cell group. In detail, the connection destination of the two transistor pairs BT21 is determined based on the control signal S1. are determined, the discharge battery cell group and the terminal pair BT01 are connected. One of the transistor pairs BT21 is connected to the terminal A1, and the other is connected to the terminal A2 by the control signal S1.

[0213] The switching circuit BT05 includes a plurality of transistor pairs BT31, a bus BT34, and a bus BT The bus BT34 is connected to the terminal B1. The bus BT35 includes: One end of each of the transistor pairs BT31 is connected to the terminal B2. The transistor BT32 branches the output of the power supply 100 to the output of the power supply 102. One end of the branched signal is connected to a bus BT34. One of the branched ends is connected to a bus BT35. The other ends of the BT09 are connected between two adjacent battery cells BT09. The other end of the transistor pair BT31 located at the most upstream of the transistor pairs BT31 is It is connected to the positive terminal of the battery cell BT09 located at the most upstream of the battery unit BT08. Among the multiple transistor pairs BT31, other than the transistor pair BT31 located at the most downstream The end of the battery unit BT08 is connected to the negative terminal of the battery cell BT09 located at the most downstream side of the battery unit BT08. .

[0214] The switching circuit BT05 switches between the transistor BT32 and the transistor BT33 in response to the control signal S2. By switching the conductive / non-conductive state of BT33, the connection of the transistor pair BT31 is The connection destination is switched to either terminal B1 or terminal B2. If T32 is conductive, transistor BT33 is non-conductive and is connected to terminal Conversely, if the transistor BT33 is in a conductive state, the transistor BT32 The transistors BT32 and BT33 are non-conductive and connected to the terminal B2. Which of the transistors BT33 is turned on is determined by a control signal S2.

[0215] Two transistor pairs, BT31, are used to connect the terminal pair BT02 to the charging battery cells. In detail, the connection destination of the two transistor pairs BT31 is determined based on the control signal S2. By determining the terminal pair BT02, the rechargeable battery cell group is connected to the terminal pair BT02. One of the transistor pairs BT31 is connected to terminal B1, and the other is connected to terminal B2 by the control signal S2.

[0216] The two transistor pairs BT31 are connected to the terminal pair BT02. Specifically, terminal B1 is the positive terminal and terminal B2 is the negative terminal. When such a voltage is applied to the terminal pair BT02, the upstream transistor pair BT31 Therefore, the transistor BT32 is turned on and the transistor BT33 is turned off. On the other hand, the downstream transistor pair BT31 is controlled by the control signal S2. The transistor BT33 is controlled to be in a conductive state and the transistor BT32 is controlled to be in a non-conductive state. It is controlled by the signal S2. Also, the voltage at terminal B1 becomes negative and the voltage at terminal B2 becomes positive. When a voltage is applied to the terminal pair BT02, the upstream transistor pair BT31 The control circuit 14 controls the transistor BT33 to be conductive and the transistor BT32 to be non-conductive. On the other hand, the downstream transistor pair BT31 is controlled by the transistor A control signal S2 is supplied to the transistor BT32 so that the transistor BT32 is in a conductive state and the transistor BT33 is in a non-conductive state. In this way, the same The terminals with polarity are connected together. The direction of the current flowing from the terminal pair BT02 is the charging The battery cell group is controlled in a charging direction.

[0217] The transformer control circuit BT06 controls the operation of the transformer circuit BT07. , 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 Based on the number of cells BT09, a transformer signal S3 is generated to control the operation of the transformer circuit BT07. This is then output to the transformer circuit BT07.

[0218] The number of battery cells BT09 included in the discharge battery cell group is equal to the number of battery cells BT09 included in the charge battery cell group. If the number of battery cells is greater than the number of BT09, an excessively large charging voltage will be applied to the battery cell group. Therefore, the transformer control circuit BT06 is The transformer circuit BT07 is designed to step down the discharge voltage (Vdis) to a level that allows the cells to be charged. It outputs a control transformer signal S3.

[0219] In addition, the number of battery cells BT09 included in the discharge battery cell group is If the number of battery cells is less than or equal to BT09, the charge required to charge the battery cell group is Therefore, the voltage transformer control circuit BT06 detects excess voltage in the charging battery cell group. The transformer circuit BT is designed to boost the discharge voltage (Vdis) to a level where an excessive charge voltage is not applied. 07.

[0220] The voltage value considered to be the excessive charging voltage is the voltage of the battery cell BT09 used in the battery module BT08. This can be determined in consideration of product specifications, etc. Also, the voltage step-up and step-down can be performed by the transformer circuit BT07. The voltage thus obtained is applied to the terminal pair BT02 as the charging voltage (Vcha).

[0221] An example of the operation of the transformer control circuit BT06 in this embodiment will now be described with reference to FIGS. 27(A) to (C) show the discharge described in FIG. 24(A) to (C). An example of the operation of the voltage transformer control circuit BT06 corresponding to the battery cell group and the charge battery cell group will be described. 27(A) to (C) are conceptual diagrams illustrating the battery control unit BT41. As described above, the battery control unit BT41 has a terminal pair BT01 and a terminal pair B T02, a switching control circuit BT03, a switching circuit BT04, and a switching circuit BT0 5, a transformer control circuit BT06, and a transformer circuit BT07.

[0222] In the example shown in FIG. 27(A), three consecutive high voltages are Cells a to c and one low-voltage cell d are connected in series. In this case, as shown in FIG. As explained above with reference to FIG. 1, the switching control circuit BT03 controls the high voltage cells a to c to the discharge voltage The low-voltage cell d is determined as the battery cell group, and the low-voltage cell d is determined as the charging battery cell group. The control circuit BT06 is based on the number of battery cells BT09 included in the discharge battery cell group. , the discharge voltage (Vdi s) to charging voltage (Vcha) is calculated.

[0223] The number of battery cells BT09 included in the discharge battery cell group is equal to the number of battery cells BT09 included in the charge battery cell group. When the number of the battery cells is larger than the number of the BT09, the discharge voltage is directly applied to the terminal pair BT02 without being transformed. When this voltage is applied, a current is applied to the battery cell BT09 in the charging battery cell group via the terminal pair BT02. There is a possibility that an excessive voltage is applied. Therefore, in the case shown in FIG. In this case, the charge voltage (Vcha) applied to the terminal pair BT02 must be lower than the discharge voltage. Furthermore, in order to charge the battery cell group, the charging voltage must be It must be greater than the total voltage of the battery cells BT09 included. Therefore, the transformer control circuit B T06 is the charging current based on the number of battery cells BT09 included in the discharge battery cell group. The conversion ratio N is set to be larger than the ratio of the number of battery cells BT09 included in the battery cell group.

[0224] The transformer control circuit BT06 determines the number of battery cells BT09 included in the discharge battery cell group as a standard. The conversion ratio N is set to 1 for the ratio of the number of battery cells BT09 included in the charging battery cell group when At this time, the charging voltage is preferably set to be about 10% higher than the voltage of the charging battery cell group. However, the charging voltage is actually equal to the voltage of the charging battery cell group. The control circuit BT06 controls the voltage of the battery cells to be equal to the charging voltage according to the conversion ratio N. This current flows to charge the battery cell group. The set value will be used.

[0225] In the example shown in FIG. 27(A), the number of battery cells BT09 included in the discharge battery cell group is 3. Since the number of battery cells included in the charging battery cell group is one, the voltage transformation control circuit The BT06 calculates a conversion ratio N that is slightly larger than 1 / 3. BT06 converts the discharge voltage into a charge voltage by converting the discharge voltage into a charge voltage according to the conversion ratio N. The transformer circuit BT07 outputs the transform signal S3 to the transformer circuit BT07. The charging voltage applied to the terminal pair BT02 is then applied to the terminal pair BT02. The battery cell BT09 included in the charging battery cell group is charged by the charging voltage.

[0226] In the example shown in FIG. 27(B) and FIG. 27(B), the conversion ratio N In the examples shown in FIG. 27(B) and FIG. 27(C), The number of battery cells BT09 included in the charging battery cell group is less than or equal to the number of battery cells BT09 included in the charging battery cell group. Therefore, the conversion ratio N is 1 or more. The inverter outputs a transformer signal S3 which boosts the load voltage and converts it into a charging voltage.

[0227] The transformer circuit BT07 adjusts the discharge voltage applied to the terminal pair BT01 based on the transformer signal S3. The transformer circuit BT07 converts the converted charging voltage into a terminal pair BT0 2. Here, the transformer circuit BT07 connects the terminal pair BT01 and the terminal pair BT02. This allows the transformer circuit BT07 to be electrically isolated from the lowest discharge battery cell group. The absolute voltage of the negative terminal of the battery cell BT09 located downstream and the most downstream of the charging battery cells This prevents a short circuit caused by a difference in absolute voltage between the negative terminal of the battery cell BT09 located at the Then, as described above, the transformer circuit BT07 converts the total voltage of the discharge battery cell group into the total voltage of the discharge battery cell group based on the transformer signal S3. The discharge voltage, which is the measured voltage, is converted into a charge voltage.

[0228] The transformer circuit BT07 is, for example, an insulated DC (Direct Current)-DC In this case, the transformer control circuit BT06 is an isolated DC- The signal that controls the on / off ratio (duty ratio) of the DC converter is the transformation signal S3. By outputting this, the charging voltage converted by the transformer circuit BT07 is controlled.

[0229] In addition, there are three types of isolated DC-DC converters: flyback type, forward type, RCC ( Ring Choke Converter, push-pull, half-blade There are various types of inverters, such as full-bridge inverter and ridge inverter, depending on the desired output voltage. The appropriate method is selected based on the result.

[0230] The configuration of the transformer circuit BT07 using an isolated DC-DC converter is shown in Fig. 28. The C-DC converter BT51 has a switch unit BT52 and a transformer unit BT53. The switch BT52 is a switch that switches the operation of the isolated DC-DC converter on and off. For example, MOSFET (Metal-Oxide-Semiconductor tor Field-Effect Transistor) and bipolar transistors The switch unit BT52 is realized by using a transformer or the like. Based on the transformer signal S3 that controls the on / off ratio, the isolated DC-DC converter The switch BT51 is periodically switched between the on and off states. Various configurations are possible depending on the type of isolated DC-DC converter used. BT53 converts the discharge voltage applied from the terminal pair BT01 into a charge voltage. The transformer section BT53 operates in conjunction with the on / off state of the switch section BT52. The discharge voltage is converted to a charge voltage according to the on / off ratio. This charge voltage is In the switching period of 2, the longer the on-state time, the larger the capacitance becomes. The voltage is increased as the time during which the switch unit BT52 is in the ON state becomes shorter in the switching period. When using an isolated DC-DC converter, the transformer section BT53 Internally, terminal pair BT01 and terminal pair BT02 can be insulated from each other.

[0231] The flow of processing by power storage device BT00 in this embodiment will be described with reference to FIG. 13 is a flowchart showing the flow of processing performed by the power storage device BT00.

[0232] First, the power storage device BT00 acquires the voltage measured for each of the plurality of battery cells BT09 (step Step S001). The power storage device BT00 aligns the voltages of the multiple battery cells BT09. It is determined whether or not a start condition for the operation is satisfied (step S002). For example, the difference between the maximum and minimum voltages measured for each of the battery cells BT09 is a predetermined If the start condition is not met (step S0 02:NO), the voltage of each battery cell BT09 is balanced, so the storage On the other hand, if the start condition is satisfied (step S 002: YES), the power storage device BT00 executes a process to make the voltages of the battery cells BT09 uniform. In this process, the power storage device BT00 performs the following on the basis of the measured voltage of each cell. It is determined whether the battery cell BT09 is a high-voltage cell or a low-voltage cell (step S003). The power storage device BT00 determines the discharge battery cell group and the charge battery cell group based on the determination result. (Step S004). Furthermore, the power storage device BT00 sets the determined discharge battery cell group as A control signal S1 that sets the connection destination of the terminal pair BT01, and a terminal A control signal S2 is generated to set the connection destination of the pair BT02 (step S005). The BT00 outputs the generated control signals S1 and S2 to the switching circuit BT04 and the switching circuit BT05. Then, the terminal pairs are output to the switching circuit BT05 by the switching circuit BT04. BT01 is connected to the discharge battery cell group, and the terminal pair BT02 is connected to the terminal pair BT03 by the switching circuit BT05. and the discharge battery cell group are connected (step S006). The number of battery cells BT09 included in the rechargeable battery cell group and the number of battery cells Based on the number of BT09, a transformed signal S3 is generated (step S007). The power storage device BT00 adjusts the discharge voltage applied to the terminal pair BT01 based on the transformation signal S3. The charge voltage is converted to a charging voltage and applied to the terminal pair BT02 (step S008). The charge of the battery cells is transferred to the charging battery cells.

[0233] In addition, in the flowchart of FIG. 29, multiple steps are listed in order, but each step The order in which the steps are executed is not limited to the order listed.

[0234] As described above, according to this embodiment, when transferring charges from the discharge battery cell group to the charge battery cell group, Like the capacitor method, the charge from the discharged battery cells is first stored and then transferred to the charging battery cells. This eliminates the need for a structure that emits electrons into a group. This increases the charge transfer efficiency per unit time. In addition, the switching circuits BT04 and BT05 can improve the Among the discharge battery cell group and the charge battery cell group, the battery cells connected to the transformer circuit are individually Can be switched.

[0235] Furthermore, the number of battery cells BT09 included in the discharge battery cell group is calculated by the transformer circuit BT07. The number of battery cells BT09 included in the charging battery cell group is determined based on the number of battery cells BT09 included in the charging battery cell group. The discharge voltage is converted to a charge voltage and applied to the terminal pair BT02. No matter what kind of battery cell BT09 is selected for the side and the charging side, charge transfer can be achieved without any problems. can.

[0236] Furthermore, by using OS transistors for the transistors BT10 and BT13, As a result, leakage occurs from the battery cell BT09 that does not belong to the charging battery cell group or the discharging battery cell group. This reduces the charge of the battery cell BT09, which does not contribute to charging or discharging. In addition, the OS transistor has a This causes the temperature of the battery cell BT09 to rise, However, normal operation, such as switching between conductive and non-conductive states according to the control signals S1 and S2, is performed. It is possible to do so. EXAMPLES

[0237] In this example, a storage battery according to one embodiment of the present invention was manufactured based on Embodiment 1. A cycle characteristic test was carried out with the storage battery.

[0238] <Configuration of storage battery 1> The configuration of the produced storage battery 1 will be described.

[0239] [Preparation of positive electrode A] First, a positive electrode slurry containing graphene as a conductive additive was prepared. The material is lithium iron phosphate (LiFePO4) and polyvinylidene fluoride (P The materials used were lithium iron phosphate, graphene oxide, polyvinylidene fluoride, and Mix them in a weight ratio of 94.2:0.8:5.0, and use N- as a dispersion medium to adjust the viscosity. Methyl-pyrrolidone (NMP) was added and kneaded to prepare a positive electrode slurry.

[0240] The positive electrode slurry prepared by the above method was applied to a positive electrode current collector (aluminum with a film thickness of 20 μm). The coating was carried out using an Iclobar coater.

[0241] Next, the slurry on the current collector was dried in the drying chamber of the coater. The test was carried out at 5°C for 15 minutes in air, and then at 75°C for 15 minutes in air. .

[0242] Next, the graphene oxide was reduced by reacting it in a solvent containing a reducing agent. The reaction was carried out at 0°C for 1 hour. Ascorbic acid was used as the reducing agent. NM P was used. The concentration of the reducing agent was 13.5 g / L.

[0243] After that, it was washed with ethanol and dried at 170°C for 10 hours. This process also serves as the thermal reduction of graphene oxide.

[0244] Next, the positive electrode active material layer was pressed by a roll press method to compact it.

[0245] In this manner, the positive electrode A used in the storage battery 1 was prepared. The amount was 11.1 mg / cm2.

[0246] [Preparation of negative electrode A] A negative electrode slurry was prepared by using a negative electrode active material, a conductive additive, a binder, and a dispersion medium. The negative electrode active material is 10 μm particle size artificial graphite (MCMB), and the conductive additive is vapor-grown carbon. Fiber (VGCF (registered trademark)), carboxymethyl cellulose sodium as binder The slurry was prepared using carboxymethylcellulose (CMC-Na) and styrene butadiene rubber (SBR). Water was used as the dispersion medium, and the weight ratio was: artificial graphite:VGCF (registered trademark):CMC-Na:SBR The mixture was mixed in a ratio of 96:1:1:2 and kneaded to obtain a negative electrode slurry.

[0247] The negative electrode slurry prepared by the above method was applied to the negative electrode current collector (rolled copper foil with a film thickness of 18 μm) by micro-soldering. Coating was done using a Robber coater.

[0248] Next, the slurry on the current collector was dried in the drying chamber of the coater. The test was carried out in an air atmosphere at 0°C for 90 seconds, and then in an air atmosphere at 80°C for 90 seconds. .

[0249] In this manner, the negative electrode A used in the storage battery 1 was prepared. The amount of graphite carried in this negative electrode was 11.1 g / cm 2 It was.

[0250] [Preparation of positive electrode B] First, a positive electrode slurry containing graphene as a conductive additive was prepared. The material is lithium iron phosphate (LiFePO4) and polyvinylidene fluoride (P The materials used were lithium iron phosphate, graphene oxide, polyvinylidene fluoride, and Mix them in a weight ratio of 94.2:0.8:5.0, and use N- as a dispersion medium to adjust the viscosity. Methyl-pyrrolidone (NMP) was added and kneaded to prepare a positive electrode slurry.

[0251] The positive electrode slurry prepared by the above method was applied to a positive electrode current collector (aluminum with a film thickness of 20 μm). The coating was performed using an Iclobar coater.

[0252] Next, the slurry on the current collector was dried in the drying chamber of the coater. The test was performed in an air atmosphere at 0°C for 4 minutes, and then in an air atmosphere at 120°C for 8 minutes. .

[0253] Next, drying was performed at 170°C for 10 hours. The drying was performed in a vacuum atmosphere. This allows the electrode to be dried and the graphene oxide to be thermally reduced.

[0254] Next, the positive electrode active material layer was pressed by a roll press method to compact it.

[0255] In this way, the positive electrode B used in the comparative battery 1 was prepared. The loading amount is 11.3mg / cm 2 It was.

[0256] [Preparation of negative electrode B] A negative electrode slurry was prepared using a negative electrode active material, a binder, and a dispersion medium. The material is 10 μm grain size artificial graphite (MCMB), and the binder is carboxymethylcellulose. Using sodium cellulose (CMC-Na) and styrene butadiene rubber (SBR) Water was used as the dispersion medium for the slurry, and the weight ratio of artificial graphite:CMC-Na:SBR was 97: The mixture in a ratio of 1:2 was kneaded to obtain a negative electrode slurry.

[0257] The negative electrode slurry prepared by the above method was applied to the negative electrode current collector (rolled copper foil with a film thickness of 18 μm) by micro-soldering. Coating was done using a Robber coater.

[0258] Next, the slurry on the current collector was dried in the drying chamber of the coater. The test was performed in an air atmosphere at 0°C for 4 minutes, and then in an air atmosphere at 120°C for 8 minutes. .

[0259] In this way, negative electrode B for use in comparative battery 1 was created. The amount of graphite carried in this negative electrode was 5. 5g / cm 2 It was.

[0260] [Electrolyte A] EC and DEC were mixed in a volume ratio of 1:1 to form a solvent, and LiTFSA was used as the Li salt. was dissolved to a concentration of 0.65 mol / kg, and LiPF6 was added as an additive at 2 wt%. A 1wt% vinylene carbonate (VC) was added to the electrolyte. The additive LiPF6 is added to prevent corrosion of the Al of the positive electrode current collector. This is to stop it.

[0261] [Electrolyte B] EC and DEC were mixed in a volume ratio of 3:7 to form the solvent, and LiPF6 was used as the Li salt. It was dissolved to a concentration of 1 mol / L, and VC was added as an additive to a concentration of 1 wt%. This was designated as electrolyte B.

[0262] [Creating storage battery 1] A laminated type storage battery was fabricated using the fabricated positive electrode A, negative electrode A, and electrolyte A. The body is an aluminum film covered with heat-sealing resin. A polypropylene (PP) with a thickness of 1.5 mm was used. This is called storage battery 1.

[0263] [Preparation of comparative battery 1] Next, a laminated type storage battery was produced using the produced positive electrode B, negative electrode B and electrolyte B. The exterior is made of aluminum film covered with heat-sealing resin. A 25 μm thick polypropylene (PP) battery was used. This battery is designated as comparative battery 1.

[0264] Next, the fabricated storage battery 1 and comparative storage battery 1 were aged. First, they were aged at 25°C and 0. After charging the battery at 01C until it reached 3.2V, the battery was charged in the glove box. The gas was then released to the outside of the exterior of the battery. The battery was then resealed and continued to be charged at 25°C. The charging was performed by CCCV, i.e., applying a constant current of 0.1C until the voltage reached 4.0V, and then applying a constant current of 0.1C until the voltage reached 4.0V. The voltage was kept constant at 4.0 V until the current reached 0.01 C. After that, the battery was heated at 40°C for 24 hours. After storing the battery for a short time, it was discharged at 25°C with the lower limit set to 2V. Charge and discharge were performed twice at a rate of 0.2C within the voltage range from 2.0V to 4.0V.

[0265] The main difference between Battery 1 and Comparative Battery 1 is that Battery 1 uses LiTFSA as the main component of the electrolyte, whereas Comparative Battery 1 uses LiPF6 as the main component of the electrolyte.

[0266] <Cycle characteristics of Battery 1 and Comparative Battery 1> Next, the cycle characteristics test will be described. The test was conducted in an environment at 60°C. The rate was 0. 5C. For the fabricated Battery 1 and Comparative Battery 1, the change in the capacity retention rate when charging and discharging were repeated is shown in Fig. 17. As shown in Fig. 17, for Comparative Battery 1, the decrease in the capacity retention rate is large when the cycle is repeated, while for Battery 1, the decrease in the capacity retention rate is relatively small. It can be seen that Battery 1 has improved cycle characteristics compared to Comparative Battery 1.

[0267] <XPS analysis> Next, in order to explore the factors for the improved cycle characteristics, after the above cycle characteristics test at 60°C, each battery was disassembled and the negative electrode was taken out, and surface analysis was performed by X-ray photoelectron spectroscopy (XPS). The negative electrodes taken out from each battery were washed with DMC, dried, and then analyzed. Also, this XPS analysis was performed without exposing the analysis sample to the atmosphere.

[0268] The conditions for XPS analysis are shown. The apparatus used for XPS analysis was Quantera SXM manufactured by PHYSICAL ELECTRONICS. For the X-ray source, monochromatized Al Kα rays (1486.6 eV) were used. The detection area was 100 μmφ, and the detection depth was above 4 nm and below 5 nm (take-off angle 45°).

[0269] First, Figure 18 shows the results of XPS analysis of the surface of the negative electrode taken from comparative battery 1. The spectrum from 00 eV to 740 eV is shown. This region is due to the 2p orbital of Fe. The spectrum shown in Figure 18 shows the peaks attributable to metallic Fe. Since the peak (around 706 eV) corresponding to the charge transport phenomenon was observed, it is possible to conclude that the surface of the negative electrode of the comparative battery 1 It was suggested that zero-valent Fe exists in the positive electrode. Since the other components of the comparative battery 1 do not contain Fe, Fe is not a positive electrode active material. The iron ions dissolved from the electrolyte, moved through the electrolyte as Fe ions, and were reduced and precipitated on the surface of the negative electrode. In other words, the positive electrode active material is damaged by the electrolyte. It is believed that the charge of comparative battery 1 was wasted when the Fe ions were reduced.

[0270] Next, FIG. 19 shows the results of XPS analysis of the surface of the negative electrode taken out of the storage battery 1. The spectrum in FIG. 19 has a similar noise level to the spectrum in FIG. Unlike the spectrum in Figure 18, the signal intensity in the relevant region exceeded the noise level. Therefore, at least in the XPS analysis, there is no peak indicating that the battery 1 It was shown that no Fe was observed on the negative electrode surface of the LiT The electrolyte in which FSA is dissolved is different from the electrolyte in which LiPF6 is dissolved, and the positive electrode active material This is because Fe is not dissolved, that is, deterioration of the positive electrode active material is not caused.

[0271] <Cross-sectional TEM observation> Next, to confirm the surface condition of the LiFePO4 particles in the positive electrode, a cross-sectional TEM (transmission electron microscope) was used. The TEM observation was performed using a Hitachi High-Technologies H-90 00NAR was used. The sample was thinned using the focused ion beam (FIB) method. In addition, the series of FIB processing and TEM observations were performed without exposing the analytical sample to the air. And so it went.

[0272] FIG. 20 shows a cross-sectional TEM image (accelerating current TEM) of the surface of the positive electrode taken out of the comparative battery 1. (voltage: 200 kV, observation magnification: 2,050,000 times) It can be seen that a layer in which no lattice fringes are observed is formed on the surface of the FePO4 particles. That is, it was found that an amorphous layer was formed on the surface of the LiFePO4 particles, and the reaction with the electrolyte was This suggests that the surface of the positive electrode active material is deteriorated due to the reaction.

[0273] Next, FIG. 21 shows the surface area of ​​the positive electrode LiFePO4 particle taken out of the storage battery 1. The cross-sectional TEM image (accelerating voltage 200 kV, observation magnification 2,050,000 times) is shown in FIG. Unlike the image in Figure 20, the image in Figure 21 shows the formation of an amorphous layer on the surface of the LiFePO4 particles. Therefore, the electrolyte does not react with the positive electrode active material, and deterioration caused by the reaction does not occur. It was confirmed that no oxidation occurred in the positive electrode active material.

[0274] Since the positive electrode active material does not deteriorate, the storage battery 1 according to one embodiment of the present invention can be cycled. The characteristics have been improved. EXAMPLES

[0275] In this example, a storage battery according to one embodiment of the present invention is manufactured based on Embodiment 1. A charge / discharge test was carried out by changing the environmental temperature using the battery, and the temperature characteristics were obtained. It was confirmed that the battery operates normally even at low temperatures of 0°C.

[0276] <Configuration of storage battery 2> The configuration of the produced storage battery 2 will be described.

[0277] [Preparation of positive electrode C] First, a positive electrode slurry containing graphene as a conductive additive was prepared. The material is lithium iron phosphate (LiFePO4) and polyvinylidene fluoride (P The materials used were lithium iron phosphate, graphene oxide, polyvinylidene fluoride, and Mix them in a weight ratio of 94.2:0.8:5.0, and use N- as a dispersion medium to adjust the viscosity. Methyl-pyrrolidone (NMP) was added and kneaded to prepare a positive electrode slurry.

[0278] The positive electrode slurry prepared by the above method was applied to a positive electrode current collector (aluminum with a film thickness of 20 μm). It was distributed.

[0279] Next, the slurry on the current collector was dried in a forced-air dryer at 80° C. for 40 minutes. The test was carried out in an air atmosphere.

[0280] Next, the graphene oxide was reduced by reacting it in a solvent containing a reducing agent. The reaction was carried out at 0°C for 1 hour. Ascorbic acid was used as the reducing agent. NM P was used. The concentration of the reducing agent was 13.5 g / L.

[0281] Then, the substrate was washed with ethanol and dried at 170°C for 10 hours in a vacuum atmosphere. This process also serves as the thermal reduction of graphene oxide.

[0282] Next, the positive electrode active material layer was pressed by a roll press method to compact it.

[0283] In this manner, the positive electrode C used in the storage battery 2 was prepared. The dose is 10.6 mg / cm 2 It was.

[0284] [Preparation of negative electrode C] Graphite modified with silicon oxide was prepared as the negative electrode active material. The artificial graphite (MCMB) used was 1 μm in diameter. The artificial graphite was modified with ethyl silicate as a coating agent. The amount of silicon oxide was set to 1 wt% relative to the artificial graphite, and the material was spray-dried twice. In addition, vapor grown carbon fiber (VGCF-H) was used as a conductive additive. (Showa Denko Co., Ltd., fiber diameter 150 nm, specific surface area 13 m 2 / g) was used. The negative electrode slurry is made using the artificial graphite produced by the above process, a conductive additive, a binder, and a dispersion medium. Sodium carboxymethylcellulose (CMC-Na) and Styrene butadiene rubber (SBR) was used. Water was used as the dispersion medium for the slurry. , artificial graphite:VGCF (registered trademark):CMC-Na:SBR=96:1:1:2 The mixture was kneaded to obtain a negative electrode slurry.

[0285] The negative electrode slurry prepared by the above method was applied to a negative electrode current collector (rolled copper foil with a film thickness of 18 μm). Ta.

[0286] Next, the sample was placed on a hot plate and dried in air. The drying process was carried out at 25°C to Start at 30°C, raise the temperature to 70°C or less, and heat for about 30 minutes. The dispersion medium, water, was evaporated by heating the mixture in a vacuum environment at 100°C. It was dried for 10 hours.

[0287] In this way, the negative electrode C to be used in the storage battery 2 was prepared. The amount of graphite carried in this negative electrode was 9.7 g. / cm 2 It was.

[0288] The electrolyte used was electrolyte A, which contains LiTFSA as the Li salt. The solvent was made by mixing them in a volume ratio of 1:1, and 0.65 mol of LiTFSA was used as the Li salt. / kg, and LiPF6 was added at 2 wt% and VC at 1 wt% as additives. The solution was added at a concentration of 0.01g / ml.

[0289] [Creating Battery 2] A laminated type storage battery was fabricated using the fabricated positive electrode C, negative electrode C, and electrolyte A. The body is an aluminum film covered with heat-sealing resin. A polypropylene (PP) sheet with a thickness of 1.5 mm was used as the storage battery 2.

[0290] Next, the fabricated storage battery 2 was aged. The aging process was the same as for storage battery 1. And so he went.

[0291] <Temperature characteristics of storage battery 2> The temperature characteristics of the storage battery 2 prepared as described above were obtained. The charge and discharge measurements were performed as follows. First, the battery was charged until it reached 4.0 V at 25°C, and then it was charged until it reached 2.0 V at 0°C. Then, it was charged at 25°C until it reached 4.0 V, and then it was discharged at 25°C until it reached 4.0 V. The battery was discharged until it reached 2.0 V. Finally, it was charged until it reached 4.0 V at 25°C. The charge and discharge were performed at 60°C until the voltage reached 2.0 V. The charge and discharge rates were 0.2 The charging and discharging were performed at CC (constant current).

[0292] The temperature characteristics are shown in Figure 22. The discharge capacity at 0°C is 100% of the discharge capacity at 25°C. The battery life was 76%, confirming that the battery of the present invention can operate normally even at a low temperature of 0°C. . [Explanation of symbols]

[0293] 100 Positive electrode current collector 101 Cathode active material layer 102 Negative electrode current collector 103 Negative electrode active material layer 104 Separator 105 Electrolyte 106 Exterior body 107 Lead Electrode 108 Sealing part 110 Lithium-ion battery 300 Battery 301 Positive electrode can 302 Anode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 310 Separator 400 Battery 402 Positive electrode 404 Negative electrode 406 Electrolyte 408 Separator 500 Battery 501 Positive electrode current collector 502 Positive electrode active material layer 503 Positive electrode 504 Negative electrode current collector 505 Negative electrode active material layer 506 negative electrode 507 Separator 508 Electrolyte 509 Exterior body 510 Positive lead electrode 511 Negative lead electrode 600 Battery 601 Positive electrode cap 602 Battery Can 603 Positive terminal 604 Positive electrode 605 Separator 606 negative electrode 607 Negative terminal 608 Insulating plate 609 Insulating plate 610 Gasket 611 PTC element 612 Safety valve mechanism 900 Circuit Board 910 Label 911 Terminal 912 Circuit 913 Storage battery 914 Antenna 915 Antenna 916 layers 917 layers 918 Antenna 919 Terminal 920 Display device 921 Sensor 922 Terminal 930 Case 930a Case 930b Case 931 negative electrode 932 Positive electrode 933 Separator 951 Terminal 952 Terminal 1700 curved surface 1701 Plane 1702 Curve 1703 Radius of curvature 1704 Center of curvature 1800 Center of curvature 1801 Film 1802 radius of curvature 1803 Film 1804 Radius of curvature 1805 Electrodes, electrolytes, etc. 7100 Display device 7102 Display section 7103 Operation button 7104 Energy storage devices 7400 Mobile Phone 7401 Case 7402 Display section 7403 Operation button 7404 External connection port 7405 Speaker 7406 Mike 7407 Energy storage devices 8021 Charging device 8022 Cable 8024 Electricity storage device 8100 Automobiles 8101 Headlight 8200 Automobiles S1 Control signal S2 Control Signal S3 Transformer Signal BT00 Power storage device BT01 terminal pair BT02 terminal pair BT03 Switching control circuit BT04 switching circuit BT05 switching circuit BT06 Transformer control circuit BT07 Transformer circuit BT08 battery part BT09 Battery Cell BT10 Transistor BT11 Bus BT12 Bus BT13 Transistor BT14 Current Control Switch BT15 Bus BT16 Bus BT17 Switch vs. BT18 Switch vs. 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 Isolated DC-DC Converter BT52 switch part BT53 transformer S001 Step S002 Step S003 Step S004 Step S005 Step S006 Step S007 Step S008 Step

Claims

1. A lithium ion storage battery having a positive electrode, a negative electrode, and an electrolyte, The positive electrode has a positive electrode current collector and a positive electrode active material, The positive electrode active material comprises lithium iron phosphate, the negative electrode has a negative electrode current collector and a negative electrode active material, The negative electrode active material includes silicon oxide and graphite, The electrolyte is LiTFSA, LiPF ６ and vinylene carbonate.

2. A lithium ion storage battery having a positive electrode, a negative electrode, and an electrolyte, The positive electrode has a positive electrode current collector and a positive electrode active material, The positive electrode active material comprises lithium iron phosphate, the negative electrode has a negative electrode current collector and a negative electrode active material, The negative electrode active material has graphite modified with silicon oxide, The electrolyte is LiTFSA, LiPF ６ and vinylene carbonate.

3. In claim 1 or 2, The negative electrode comprises carbon fiber.

Images