Batteries, battery packs, vehicles, and stationary power supplies

Abstract

To provide a battery, a battery pack, a vehicle, and a stationary power source, having excellent life performance.SOLUTION: A battery 1 is provided including a positive electrode 5, a negative electrode 3, and a water-containing electrolyte. The negative electrode 3 includes a negative electrode active material-containing layer including a Ti-containing oxide and a binder containing water. Moreover, the battery 1 satisfies the following expression (1): 0.2≤Wbind / WH2O≤15 (1), where Wbind denotes a content (% by weight) of the binder containing water in the negative electrode active material-containing layer, and WH2O denotes a content (% by weight) of the water in the electrolyte.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments of the present invention relate to batteries, battery packs, vehicles, and stationary power supplies. [Background technology]

[0002] In aqueous lithium secondary batteries equipped with a negative electrode containing titanium composite oxide, volume changes occur in the titanium composite oxide during charging and discharging, raising concerns about electrolyte depletion and disruption of electron conduction paths. To prevent electrolyte depletion, reducing electrode density has been proposed. However, in aqueous batteries such as aqueous lithium secondary batteries, reducing electrode density too much makes water electrolysis more likely, thus degrading charge and discharge characteristics. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-156895 [Patent Document 2] Japanese Patent Publication No. 2018-163893 [Non-patent literature]

[0004] [Non-Patent Document 1] Jijian Xu et al., Aqueous electrolyte design for super-stable 2.5V LiMn2O4 / Li4Ti5O12 pouch cells, Nature Energy volume 7, pages186-193 (2022) [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The problem we aim to solve is to provide batteries, battery packs, vehicles, and stationary power supplies with superior lifespan performance. [Means for solving the problem]

[0006] According to one embodiment, a battery is provided that includes a positive electrode, a negative electrode, and an electrolyte containing water. The negative electrode includes a negative electrode active material containing a Ti-containing oxide and a water-containing binder. The aqueous binder is at least one selected from the group consisting of carboxymethylcellulose and its salts, styrene-butadiene rubber, and polyvinylpyrrolidone. Furthermore, the battery satisfies equation (1) below.

[0007] 0.2 ≤ W bind / W H2O ≤15 (1) However, W bind This is the content (by weight) of the water-containing binder in the negative electrode active material layer, W H2O This represents the water content (by weight) in the electrolyte. W bind It is between 0.8% and 6% by weight. H2O It is 10% by weight or less.

[0008] According to one embodiment, a battery pack is provided that includes the battery of the embodiment.

[0009] Furthermore, according to the embodiment, a vehicle equipped with the battery pack of the embodiment is provided.

[0010] Furthermore, according to the embodiment, a stationary power supply equipped with the battery pack of the embodiment is provided. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic cross-sectional view showing an example of a secondary battery according to this embodiment. [Figure 2] A schematic cross-sectional view of the secondary battery shown in Figure 1, along the line II-II. [Figure 3] A partially cutaway perspective view schematically showing another example of a secondary battery according to the embodiment. [Figure 4] Figure 3 shows an enlarged cross-sectional view of section E of the secondary battery. [Figure 5] A schematic perspective view showing an example of a battery pack according to this embodiment. [Figure 6] An exploded perspective view schematically showing another example of a battery pack according to the embodiment. [Figure 7]A block diagram showing an example of an electric circuit of a battery pack shown in FIG. 6. [Figure 8] A partial transparent view schematically showing an example of a vehicle according to an embodiment. [Figure 9] A block diagram showing an example of a system including a stationary power source according to an embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0012] (First Embodiment) According to the first embodiment, a battery is provided that includes a positive electrode, a negative electrode, and an electrolyte containing water. The negative electrode includes a negative electrode active material-containing layer containing a Ti-containing oxide and a water-containing binder. Further, the battery satisfies the following formula (1).

[0013] 0.2 ≦ W bind / W H2O ≦ 15 (1) However, W bind is the content (% by weight) of the water-containing binder in the negative electrode active material-containing layer, and W H2O is the content (% by weight) of water in the electrolyte.

[0014] In a battery provided with an electrolyte containing water, in order to prevent the binder from dissolving in the electrolyte, a binder soluble in an organic solvent such as polyvinylidene fluoride (PVdF) is used. As a result of intensive research, the inventors have found that when the content of the water-containing binder in the negative electrode active material-containing layer and the content of water in the electrolyte satisfy the relationship of formula (1), generation of hydrogen gas due to electrolysis of water can be suppressed, and the water-containing binder is not dissolved in the electrolyte, the water-containing binder is retained in the electrolyte, and the adhesion between the active material-containing layer and the current collector and the retention of the aqueous electrolyte in the active material-containing layer can be improved for the first time. Therefore, the battery of the embodiment can improve the charge / discharge cycle performance.

[0015] The ratio W bind / W H2O The reason for specifying the value within the range of the above formula (1) will be explained. The ratio W bind / W H2OBy setting the value to 0.2 or higher, the water weight relative to the weight of the water-containing binder can be appropriately reduced, making the water-containing binder less likely to dissolve in the electrolyte. This maintains the bonding between the active material-containing layer and the current collector, thereby suppressing a decrease in cycle performance. Specific W bind / W H2O If the value is 15 or less, the electrolyte can be easily impregnated into the water-containing binder. Specific W bind / W H2O The preferred range for the value is between 1 and 8.

[0016] The following provides details about the negative electrode, positive electrode, and electrolyte. <Negative electrode> The negative electrode includes a negative electrode current collector and a negative electrode active material-containing layer formed on or laminated on one or both sides of the negative electrode current collector. The negative electrode active material-containing layer contains a negative electrode active material and a water-containing binder.

[0017] The negative electrode current collector may be formed from a material that is electrochemically stable at the potential in which lithium (Li) is inserted into and removed from the active material. Examples of negative electrode current collectors include conductive sheets containing conductive materials and polymer materials, conductive sheets containing at least one metallic element selected from the group consisting of Pb, Bi, Zn, Sb, and Sn, metallic foils such as copper, nickel, stainless steel, or aluminum, and aluminum alloy foils containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. Examples of polymer materials for conductive sheets include polyethylene, polypropylene, polyethylene terephthalate, polyacrylonitrile, polymethyl methacrylate, and polyvinylidene fluoride. It is preferable to use conductive fillers such as carbonaceous materials for the conductive material. Examples of carbonaceous materials include carbon black, Ketjenblack, graphite, fibrous carbon, and carbon nanotubes. The types of conductive materials and polymer materials can be one or more.

[0018] The thickness of the negative electrode current collector is preferably between 5 μm and 50 μm. A current collector with such a thickness can balance electrode strength and weight reduction.

[0019] The negative electrode current collector may include portions on its surface where the active material-containing layer is not formed. These portions can function as current-collecting tabs or current-collecting leads.

[0020] The negative electrode active material contains a Ti-containing oxide. This Ti-containing oxide is, for example, lithium ion (Li + This is a Ti-containing oxide that can be transformed into a Ti-containing oxide containing Li through an intercalation-deintercalation reaction or a charge-discharge reaction of lithium ions (Li). Therefore, this Ti-containing oxide may be a Ti-containing oxide that does not contain Li. This Li-free Ti-containing oxide is one in which lithium ions (Li) are absorbed during oxide synthesis or during the process of ion synthesis. + Before the intercalation / deintercalation reaction or the charge / discharge reaction occurs, the material is Li-free. Due to the intercalation / deintercalation reaction of lithium ions or irreversible reactions that occur during the charge / discharge reaction, Li may remain in the Ti-containing oxide. Therefore, a Ti-containing oxide that is Li-free includes one that is substantially Li-free.

[0021] Examples of Ti-containing oxides include niobium-titanium-containing oxides and titanium oxides. Each oxide is Li-free during oxide synthesis, before lithium ion intercalation / deintercalation reactions occur, or before charge-discharge reactions occur. However, they can be transformed into Li-containing Ti-containing oxides through lithium ion intercalation / deintercalation reactions or charge-discharge reactions. Since the lithium ion intercalation / deintercalation reaction of niobium-titanium-containing oxides is a solid solution reaction, the operating potential of the negative electrode containing niobium-titanium-containing oxide has a range. For example, the operating potential of a negative electrode containing niobium-titanium-containing oxide with a crystalline phase represented by TiNb2O7 ranges from approximately 1.7V to approximately 0.7V. Therefore, a negative electrode containing niobium-titanium-containing oxide can be set to a potential where film formation is likely to occur, thus promoting the formation of films such as nitrogen-containing compounds on the negative electrode active material. On the other hand, Li4Ti5O 12Spinel-type lithium titanate, such as the one shown, has a composition containing Li even before the intercalation and deintercalation reaction of lithium ions occurs during synthesis. The operating potential of the negative electrode containing spinel-type lithium titanate is constant at 1.55V. Therefore, it is difficult to set the potential of the negative electrode containing spinel-type lithium titanate to a potential favorable for film formation, such as that of nitrogen-containing compounds, and there is a risk that a film will not be uniformly formed on the negative electrode active material.

[0022] Furthermore, by using at least one of niobium-titanium-containing oxide or titanium oxide as the negative electrode active material, a high electromotive force can be obtained by combining it with, for example, lithium manganese composite oxide or lithium nickel-cobalt-manganese composite oxide as the positive electrode active material.

[0023] Examples of niobium-titanium-containing oxides include TiNb2O7, Ti2Nb2O9, and Ti2Nb 10 O 29 TiNb 14 O 37 and TiNb 24 O 62 Examples include those containing at least one crystalline phase selected from the group consisting of the following. The niobium-titanium-containing oxide may be a substituted niobium-titanium composite oxide in which at least a portion of Nb and / or Ti is substituted with a different element. Examples of substituted elements include Na, K, Ca, Co, Ni, Si, P, V, Cr, Mo, Ta, Zr, Mn, Fe, Mg, B, Pb, and Al. The substituted niobium-titanium composite oxide may contain one type of substituted element or two or more types of substituted elements. The active material particles may contain one type of niobium-titanium-containing oxide or multiple types of niobium-titanium-containing oxides. Preferably, the niobium-titanium-containing oxide contains Nb2TiO7 with a monoclinic structure. In this case, an electrode with excellent capacity and rate performance can be obtained.

[0024] As an example of a monoclinic niobium-titanium-containing oxide, Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δA compound represented by the formula is shown below. Here, M1 is at least one selected from the group consisting of Zr, Si, and Sn. M2 is at least one selected from the group consisting of V, Ta, and Bi. The subscripts in the empirical formula represent 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0025] Other examples of monoclinic niobium-titanium-containing oxides include Ti 1-y M3 y+z Nb 2-z O 7-δ A compound represented by the formula is shown below. Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. In the compositional formula, each subscript has the following properties: 0≦y<1, 0≦z<2, -0.3≦δ≦0.3.

[0026] Another example of a monoclinic niobium-titanium-containing oxide is Li a TiM b Nb 2±β O 7±σ Examples include those represented as (0≦a≦5, 0≦b≦0.3, 0≦β≦0.3, 0≦σ≦0.3, where M is at least one element selected from the group consisting of Fe, V, Mo, and Ta).

[0027] Titanium oxides include, for example, monoclinic titanium oxide, rutile titanium oxide, and anatase titanium oxide. Each crystalline structure of titanium oxide has a composition of TiO2 before charging and a composition of Li after charging. x It can be represented as TiO2 (where x is 0 ≤ x ≤ 1). Furthermore, the pre-charge structure of monoclinic titanium oxide can be represented as TiO2(B).

[0028] The negative electrode active material can be one type or two or more types.

[0029] The negative electrode active material is contained in the negative electrode active material-containing layer, for example, in the form of particles. The negative electrode active material particles may be primary particles, secondary particles which are aggregates of primary particles, or mixtures of individual primary and secondary particles. The shape of the particles is not particularly limited and can be, for example, spherical, elliptical, flattened, or fibrous.

[0030] The average particle size (diameter) of the primary particles of the negative electrode active material is preferably 3 μm or less, and more preferably 0.01 μm or more and 1 μm or less. The average particle size (diameter) of the secondary particles of the negative electrode active material is preferably 30 μm or less, and more preferably 5 μm or more and 20 μm or less.

[0031] A water-containing binder can be any binder capable of containing water, and may or may not actually contain water. Examples of water-containing binders include water-soluble binders and hydrophilic binders. Examples of water-containing binders include carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinylpyrrolidone (PVP), and salts of CMC (e.g., sodium salt of CMC, potassium salt of CMC). One or more types of water-containing binders can be used. CMC and salts of CMC can each increase the viscosity of the negative electrode slurry. On the other hand, SBR has the effect of decreasing viscosity when it contains water. By using at least one of CMC or a salt of CMC and SBR, it becomes easy to adjust the viscosity of the negative electrode slurry to the desired range.

[0032] W bind This can be increased to 0.8% by weight or more and 6% by weight or less. This makes it easier to retain the water-containing binder in the electrolyte without dissolving it in the electrolyte, thereby further improving charge-discharge cycle performance. bind A more preferable range is 2% by weight or more and 6% by weight or less.

[0033] The negative electrode active material-containing layer may also contain conductive agents in addition to the negative electrode active material and binder. Conductive agents are added as needed to improve current collection performance and reduce contact resistance between the active material and the current collector.

[0034] Examples of conductive agents include carbonaceous materials such as acetylene black, Ketjenblack, graphite, and coke. The conductive agent may be a single type or a mixture of two or more types.

[0035] The mixing ratio of the negative electrode active material and the conductive agent in the negative electrode active material-containing layer can be changed as appropriate. For example, the content of the negative electrode active material in the negative electrode active material-containing layer can be 68% by weight or more and 96% by weight or less. On the other hand, the content of the conductive agent in the negative electrode active material-containing layer can be 2% by weight or more and 30% by weight or less. By setting the amount of conductive agent to 2% by weight or more, the current collection performance of the negative electrode active material-containing layer can be improved. Furthermore, it is preferable to set the content of the conductive agent to 30% by weight or less in order to achieve high capacity.

[0036] A nitrogen-containing compound may be present on at least a portion of the surface of the negative electrode active material-containing layer. The nitrogen-containing compound is a compound containing a nitrogen atom (N). The nitrogen-containing compound can contribute to suppressing the electrolysis of water. The surface portion where the nitrogen-containing compound is present is not particularly limited, but it can be the portion of the negative electrode active material-containing layer surface that is not in contact with the negative electrode current collector and faces the positive electrode via a separator. An example of this portion is the main surface of the negative electrode active material-containing layer that constitutes the surface of the negative electrode. An example of a nitrogen-containing compound is a compound having a functional group containing a nitrogen atom (N). An example of a functional group containing a nitrogen atom (N) is an amide bond. Therefore, a compound containing an amide bond may be present on at least a portion of the surface of the negative electrode active material-containing layer. Examples of compounds containing an amide bond include urea, N-methylurea, N,N′-dimethylpropyleneurea, acetamide, and thioacetamide. There may be one or more types of compounds containing an amide bond.

[0037] The negative electrode can be manufactured, for example, by the following method. First, a slurry is prepared by suspending the negative electrode active material, conductive agent, and aqueous binder in an aqueous solvent. This slurry is applied to one or both sides of the current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. After that, this laminate is pressed. In this way, the negative electrode is manufactured.

[0038] <Positive electrode> The positive electrode comprises a positive electrode current collector and a positive electrode active material-containing layer formed on or laminated on one or both sides of the positive electrode current collector. The positive electrode active material-containing layer contains positive electrode active material. The positive electrode active material-containing layer may further contain a conductive agent and a binder (positive electrode binder). The conductive agent is added as needed to enhance current collection performance and reduce contact resistance between the active material and the current collector. The binder has the effect of binding the active material, conductive agent, and current collector together.

[0039] The positive electrode current collector may be formed from a material that is electrochemically stable at the potential in which lithium (Li) is inserted into and removed from the active material. Examples of positive electrode current collectors include conductive sheets containing conductive materials and polymer materials, conductive sheets containing at least one metallic element selected from the group consisting of Pb, Bi, Zn, Sb, and Sn, metallic foils such as nickel, stainless steel, or aluminum, and aluminum alloy foils containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. The polymer materials and conductive materials of the conductive sheets can be similar to those described for the negative electrode current collector.

[0040] The thickness of the positive electrode current collector is preferably between 5 μm and 50 μm. A current collector with such a thickness can balance electrode strength and weight reduction.

[0041] The positive electrode current collector may include portions on its surface where the active material-containing layer is not formed. These portions can function as current-collecting tabs or current-collecting leads.

[0042] As the positive electrode active material, a compound having a lithium ion intercalation and deintercalation potential of 3 V (vs. Li / Li + ) or more and 5.5 V or less (vs. Li / Li + ) based on the potential of metallic lithium can be used. The positive electrode may contain one type of positive electrode active material or may contain two or more types of positive electrode active materials.

[0043] Examples of the positive electrode active material include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt aluminum composite oxide, lithium nickel cobalt manganese composite oxide, spinel-type lithium manganese nickel composite oxide, lithium manganese cobalt composite oxide, lithium iron oxide, lithium fluorinated iron sulfate, phosphate compounds having an olivine crystal structure (for example, Li x FePO4 (0 < x ≦ 1), Li x MnPO4 (0 < x ≦ 1)), etc. The phosphate compound having an olivine crystal structure is excellent in thermal stability.

[0044] Examples of the positive electrode active material capable of obtaining a high positive electrode potential include lithium nickel cobalt manganese composite oxide (Li x Ni 1-y-z Co y Mn z O2; 0 < x ≦ 1, 0 < y < 1, 0 < z < 1, y + z < 1), for example, spinel-structured Li x Mn2O4 (0 < x ≦ 1), Li x MnO2 (0 < x ≦ 1)) and other lithium manganese composite oxides, for example, Li x Ni 1-y Al y O2 (0 < x ≦ 1, 0 < y < 1) and other lithium nickel aluminum composite oxides, for example, Li x CoO2 (0 < x ≦ 1)) and other lithium cobalt composite oxides, for example, Li x Ni 1-y―z Co y Mn z O2 (0 < x ≦ 1, 0 < y < 1, 0 ≦ z < 1) and other lithium nickel cobalt composite oxides, for example, Li x Mn y Co 1-yLithium manganese cobalt composite oxides such as O2 (0 < x ≤ 1, 0 < y < 1), for example Li x Mn 1-y Ni y Spinel-type lithium manganese nickel composite oxides such as O4 (0 < x ≤ 1, 0 < y < 2, 0 < 1 - y < 1), for example Li x FePO4 (0 < x ≤ 1), Li x Fe 1-y Mn y PO4 (0 < x ≤ 1, 0 ≤ y ≤ 1), Li x Lithium phosphates having an olivine structure such as CoPO4 (0 < x ≤ 1), iron fluorosulfate (for example Li x FeSO4F (0 < x ≤ 1)) can be mentioned.

[0045] The positive electrode active material is contained in the positive electrode, for example, in the form of particles. The positive electrode active material particles can be single primary particles, secondary particles that are aggregates of primary particles, or a mixture of primary particles and secondary particles. The shape of the particles is not particularly limited, and can be, for example, spherical, elliptical, flat, or fibrous.

[0046] The average particle diameter (diameter) of the primary particles of the positive electrode active material is preferably 10 μm or less, more preferably 0.1 μm or more and 5 μm or less. The average particle diameter (diameter) of the secondary particles of the positive electrode active material is preferably 100 μm or less, more preferably 10 μm or more and 50 μm or less.

[0047] The binder is blended to fill the gaps between the dispersed positive electrode active materials and to bind the positive electrode active material and the positive electrode current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine rubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these may be used as the binder, or two or more of them may be combined and used as the binder.

[0048] Conductive agents are added to enhance current collection performance and reduce contact resistance between the positive electrode active material and the positive electrode current collector. Examples of conductive agents include vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, and carbonaceous materials such as graphite. One of these may be used as a conductive agent, or two or more may be used in combination. Conductive agents may also be omitted.

[0049] In the positive electrode active material-containing layer, it is preferable that the positive electrode active material and the binder are blended in proportions of 80% to 98% by weight and 2% to 20% by weight, respectively.

[0050] Sufficient electrode strength can be obtained by using a binder amount of 2% by weight or more. Furthermore, the binder can function as an insulator. Therefore, reducing the binder amount to 20% by weight or less reduces the amount of insulator contained in the electrode, thereby reducing internal resistance.

[0051] When a conductive agent is added, it is preferable that the positive electrode active material, binder, and conductive agent are blended in proportions of 77% to 95% by weight, 2% to 20% by weight, and 3% to 15% by weight, respectively.

[0052] The above-mentioned effects can be achieved by increasing the amount of conductive agent to 3% by weight or more. Furthermore, by reducing the amount of conductive agent to 15% by weight or less, the proportion of conductive agent in contact with the electrolyte can be reduced. This lower proportion reduces the decomposition of the electrolyte under high-temperature storage conditions.

[0053] The positive electrode can be manufactured by, for example, preparing a slurry by suspending a positive electrode active material, a conductive agent, and a binder in a solvent. This slurry is then applied to one or both sides of a current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. After that, this laminate is pressed. In this way, the positive electrode is manufactured. Alternatively, the positive electrode may be manufactured by the following method: First, the active material, conductive agent, and binder are mixed to obtain a mixture. Next, this mixture is formed into pellets. Then, these pellets are placed on the current collector to obtain the positive electrode. <Aqueous electrolyte> Electrolytes include water. Hereafter, electrolytes containing water may be referred to as aqueous electrolytes.

[0054] Aqueous electrolytes comprise an aqueous solvent and an electrolyte salt dissolved in the aqueous solvent. Aqueous electrolytes may be in liquid or gel form. A liquid aqueous electrolyte is, for example, an aqueous solution prepared by dissolving an electrolyte salt as a solute in an aqueous solvent. A gel-like aqueous electrolyte is prepared, for example, by mixing and compounding a liquid aqueous electrolyte with a polymer compound. Examples of polymer compounds include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), and polyethylene oxide (PEO). When aqueous electrolytes are held in both the negative electrode active material-containing layer and the positive electrode active material-containing layer, the types of aqueous electrolytes may be the same or different.

[0055] As an aqueous solvent, a solution containing water can be used. The solution containing water may be pure water or a mixed solvent of water and an organic solvent. For example, the aqueous solvent contains water in a proportion of 50% by volume or more.

[0056] W H2O This can be reduced to 10% by weight or less. This suppresses the electrolysis of water, thereby further improving charge-discharge cycle performance. H2O The lower limit can be set to 0.3% by weight. That is, W H2O This can be between 0.3% and 10% by weight.

[0057] As the electrolyte salt, for example, lithium salts, sodium salts, or mixtures thereof can be used. One or more types of electrolyte salts can be used.

[0058] The electrolyte salt content in the aqueous electrolyte can be in the range of 45% to 65% by weight, more preferably in the range of 50% to 60% by weight.

[0059] Examples of lithium salts that can be used include lithium chloride (LiCl), lithium bromide (LiBr), lithium hydroxide (LiOH), lithium sulfate (Li2SO4), lithium nitrate (LiNO3), lithium acetate (CH3COOLi), lithium oxalate (Li2C2O4), lithium carbonate (Li2CO3), lithium difluorooxalate borate (LiDFOB, C2BF2LiO4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI; LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiFSI; LiN(FSO2)2), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI; LiN(SO2C2F5)2), and lithium bisoxalate borate (LiBOB: LiB[(OCO)2]2).

[0060] The lithium salt preferably contains at least one selected from the group consisting of LiN(FSO2)2, LiN(CF3SO2)2, and LiN(SO2C2F5)2. Each lithium salt is solid at or near room temperature, but can change to a liquid state through a eutectic reaction with a compound containing an amide bond. Therefore, the water content W in the aqueous electrolyte H2O This can contribute to reducing [the amount of [the substance]]. Lithium salts containing LiTFSI (LiN(CF3SO2)2) are preferred.

[0061] Examples of sodium salts that can be used include sodium chloride (NaCl), sodium sulfate (Na2SO4), sodium hydroxide (NaOH), sodium nitrate (NaNO3), and sodium trifluoromethanesulfonylamide (NaTFSA).

[0062] Aqueous electrolytes include chloride ions (Cl) as anion species. - ), hydroxide ion (OH - ), sulfate ions (SO4 2- ), nitrate ion (NO3 - It may include at least one selected from the following:

[0063] The aqueous electrolyte may contain a compound containing an amide bond. This prevents the aqueous binder from dissolving in the aqueous electrolyte, allowing it to cover the surface of the negative electrode active material particles while still containing the aqueous electrolyte. As a result, even if the volume of the negative electrode changes due to charging and discharging, the depletion of the aqueous electrolyte can be prevented, thereby improving the charge-discharge characteristics. The compound containing an amide bond can form a liquid mixture through a eutectic reaction with at least one lithium salt selected from the group consisting of LiTFSI, LiFSI, and LiBETI. Therefore, an aqueous electrolyte containing a compound containing an amide bond and at least one lithium salt selected from the group consisting of LiTFSI, LiFSI, and LiBETI can have the desired lithium ion concentration even with a small amount of aqueous solvent. Thus, it is possible to suppress the electrolysis of water without impairing the ionic conductivity of the aqueous electrolyte.

[0064] Examples of compounds containing an amide bond include urea, N-methylurea, N,N′-dimethylpropyleneurea, acetamide, and thioacetamide. A compound may contain one or more types of amide bonds.

[0065] The content of compounds containing amide bonds in the aqueous electrolyte can be 30% to 55% by weight, preferably 30% to 45% by weight. If the content of compounds containing amide bonds in the aqueous electrolyte is low, a coating may not form on the surface of the negative electrode active material particles. In addition, some of the lithium salt may precipitate in the solvent as a solid. On the other hand, if the content of compounds containing amide bonds in the aqueous electrolyte is high, the coating formed on the surface of the negative electrode active material particles may be excessive, potentially increasing the resistance of the negative electrode.

[0066] The aqueous electrolyte may contain potassium hydroxide (KOH). Potassium hydroxide can function as a catalyst for the reaction that forms a film on the surface of the negative electrode active material particles. Therefore, by containing a compound containing an amide bond and potassium hydroxide in the aqueous electrolyte, film formation on the surface of the negative electrode active material particles can be promoted.

[0067] The pH of the aqueous electrolyte is preferably between 3 and 14, and more preferably between 4 and 13. When different electrolytes are used for the negative electrode and the positive electrode, the pH of the negative electrode electrolyte is preferably within the range of 3 to 14, and the pH of the positive electrode electrolyte is preferably within the range of 1 to 8.

[0068] When the pH of the negative electrode electrolyte is within the above range, the hydrogen evolution potential at the negative electrode decreases, thereby suppressing hydrogen evolution at the negative electrode. This improves the battery's storage performance and cycle life performance. When the pH of the positive electrode electrolyte is within the above range, the oxygen evolution potential at the positive electrode increases, thus reducing oxygen evolution at the positive electrode. This improves the battery's storage performance and cycle life performance. It is more preferable that the pH of the positive electrode electrolyte be within the range of 3 to 7.5.

[0069] The aqueous electrolyte may contain a surfactant. Examples of surfactants include polyoxyalkylene alkyl ethers, polyethylene glycol, polyvinyl alcohol, thiourea, 3,3'-dithiobis(1-propanephosic acid) disodium, dimercaptothiadiazole, boric acid, oxalic acid, malonic acid, saccharin, sodium naphthalene sulfonate, gelatin, potassium nitrate, aromatic aldehydes, heterocyclic aldehydes, and other nonionic surfactants. Surfactants may be used individually or in combination of two or more types.

[0070] The battery of the embodiment may further include at least one of the following components: a separator or an outer casing.

[0071] <Separator> A separator is placed, for example, between the positive and negative electrodes. Alternatively, the separator may include one that covers only one of the electrodes, either the positive or the negative.

[0072] Separators can have a porous structure. Examples of porous separators include nonwoven fabrics, films, and paper. Examples of constituent materials for porous separators that make up nonwoven fabrics, films, and paper include polyolefins such as polyethylene and polypropylene, and cellulose. Preferred examples of porous separators include nonwoven fabrics containing cellulose fibers and porous films containing polyolefin fibers.

[0073] The porosity of the porous separator is preferably 60% or higher. Furthermore, the fiber diameter is preferably 10 μm or less. By reducing the fiber diameter to 10 μm or less, the affinity of the porous separator to the electrolyte is improved, thereby reducing battery resistance. A more preferable range for fiber diameter is 3 μm or less. Cellulose fiber-containing nonwoven fabrics with a porosity of 60% or higher have good electrolyte impregnation properties and can achieve high output performance from low to high temperatures. A more preferable range for porosity is 62% to 80%.

[0074] The porous separator has a thickness of 20 μm to 100 μm and a density of 0.2 g / cm³. 3 More than 0.9g / cm 3 The following is preferable. Within this range, it is possible to balance mechanical strength and reduced battery resistance, and to provide a secondary battery with high output and suppressed internal short circuits. In addition, thermal contraction of the separator in high-temperature environments is reduced, and good high-temperature storage performance can be achieved.

[0075] As a separator, a composite separator may be used, which includes a porous separator and a layer containing inorganic particles formed on one or both sides of the porous separator. Examples of inorganic particles include aluminum oxide and silicon oxide.

[0076] A solid electrolyte layer may be used as a separator. The solid electrolyte layer may contain solid electrolyte particles and polymer components. The solid electrolyte layer may consist only of solid electrolyte particles. The solid electrolyte layer may contain one type of solid electrolyte particle or multiple types of solid electrolyte particles. The solid electrolyte layer may contain at least one selected from the group consisting of plasticizers and electrolyte salts. If the solid electrolyte layer contains an electrolyte salt, for example, the alkali metal ion conductivity of the solid electrolyte layer can be further enhanced. The polymer material may take the form of, for example, granular or fibrous.

[0077] The solid electrolyte layer is preferably in sheet form and has few or no pores such as pinholes. The thickness of the solid electrolyte layer is not particularly limited, but is, for example, 150 μm or less, and preferably in the range of 20 μm to 50 μm.

[0078] The polymer component used in the solid electrolyte layer should preferably be insoluble in aqueous solvents. Examples of polymer components that satisfy this condition include polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and fluorine-containing polymer components. By using a fluorine-containing polymer component, water repellency can be imparted to the separator. Furthermore, inorganic solid electrolytes have high stability in water and excellent lithium ion conductivity. By compounding a lithium ion-conductive inorganic solid electrolyte with a fluorine-containing polymer component, a flexible solid electrolyte layer with alkali metal ion conductivity can be realized. Since the separator made of this solid electrolyte layer can reduce resistance, the high-current performance of secondary batteries can be improved.

[0079] Examples of fluorine-containing polymer components include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), ethylenetetrafluoroethylene copolymer, and polyvinylidene fluoride (PVdF). The number of fluorine-containing polymer components can be one or more.

[0080] When the solid electrolyte layer contains polymer components, the content of polymer components in the solid electrolyte layer is preferably 1% by weight or more and 20% by weight or less. Within this range, high mechanical strength can be obtained and resistance can be reduced when the thickness of the solid electrolyte layer is in the range of 10 to 100 μm. Furthermore, there is a low risk that the solid electrolyte will hinder lithium ion conductivity. A more preferable range for this percentage is 3% by weight or more and 10% by weight or less.

[0081] As the solid electrolyte, it is preferable to use an inorganic solid electrolyte. The inorganic solid electrolyte is a solid material that has Li ion conductivity. Here, having Li ion conductivity means that at 25°C it has a conductivity of 1 × 10⁻⁶. -6 This refers to exhibiting a lithium ion conductivity of S / cm or higher. Examples of inorganic solid electrolytes include oxide-based solid electrolytes and sulfide-based solid electrolytes. Specific examples of inorganic solid electrolytes are as follows.

[0082] As the oxide-based solid electrolyte, it is preferable to use a lithium phosphate solid electrolyte having a NASICON (Sodium (Na) Super Ionic Conductor) type structure and represented by the general formula Li 1+x Mα2(PO4)3. In the above general formula, Mα is, for example, one or more selected from the group consisting of titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The subscript x is within the range of 0≦x≦2.

[0083] Specific examples of the lithium phosphate solid electrolyte having a NASICON type structure include LATP compounds represented by Li 1+x Al x Ti 2-x (PO4)3 with 0.1≦x≦0.5; compounds represented by Li 1+x Al y Mβ 2-y (PO4)3 where Mβ is one or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn, and Ca and 0≦x≦1 and 0≦y≦1; compounds represented by Li 1+x Al x Ge 2-x (PO4)3 with 0≦x≦2; and compounds represented by Li 1+x Al x Zr 2-x (PO4)3 with 0≦x≦2; Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 where Mγ is one or more selected from the group consisting of Ti and Ge and 0<x≦2, 0≦y<3; compounds represented by Li 1+2x Zr 1-x Ca x (PO4)3 with 0≦x<1 can be mentioned.

[0084] In addition, as the oxide-based solid electrolyte, in addition to the above lithium phosphate solid electrolyte, Li x PO y N zAmorphous lipon compounds (e.g., Li) are represented as such that 2.6≦x≦3.5, 1.9≦y≦3.8, and 0.1≦z≦1.3. 2.9 PO 3.3 N 0.46 ); Garnet-type structure La 5+x A x La 3-x Mδ2O 12 A compound represented as follows: A is one or more selected from the group consisting of Ca, Sr, and Ba, and Mδ is one or more selected from the group consisting of Nb and Ta, and 0 ≤ x ≤ 0.5; Li3Mδ 2-x L2O 12 A compound represented by where Mδ is 1 or more selected from the group consisting of Nb and Ta, and L may contain Zr, with 0 ≤ x ≤ 0.5; Li 7-3x Al x La3Zr3O 12 Compounds represented by 0 ≤ x ≤ 0.5; Li 5+x La3MCSR 2-x Zr x O 12 Represented by , where Mδ is 1 or more selected from the group consisting of Nb and Ta, and 0 ≤ x ≤ 2, it is an LLZ compound (e.g., Li7La3Zr2O 12 ); and having a perovskite-type structure La 2 / 3-x Li x Examples include compounds represented as TiO3 where 0.3 ≤ x ≤ 0.7.

[0085] One or more of the above compounds can be used as a solid electrolyte. Two or more of the above solid electrolytes may also be used.

[0086] <Exterior components> The outer casing contains at least a positive electrode, a negative electrode, a separator, and an aqueous electrolyte. For example, the outer casing can be a metal container, a laminated film container, or a resin container. Metal containers can be metal cans made of nickel, iron, or stainless steel, and may be rectangular or cylindrical in shape. Resin containers can be made of polyethylene or polypropylene.

[0087] The thickness of the laminating film is, for example, 0.5 mm or less, and preferably 0.2 mm or less.

[0088] As the laminate film, a multilayer film is used that includes multiple resin layers and a metal layer interposed between these resin layers. The resin layers include polymer materials such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET). The metal layer is preferably made of aluminum foil or aluminum alloy foil for weight reduction. The laminate film can be molded into the shape of an exterior component by sealing it by heat fusion.

[0089] The thickness of the metal container wall is, for example, 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.2 mm or less.

[0090] Metal containers are made from, for example, aluminum or aluminum alloys. Aluminum alloys preferably contain elements such as magnesium, zinc, and silicon. If aluminum alloys contain transition metals such as iron, copper, nickel, and chromium, their content is preferably 100 ppm by weight or less.

[0091] The shape of the exterior components is not particularly limited. For example, the exterior components may be flat (thin), rectangular, cylindrical, coin-shaped, or button-shaped. The exterior components can be appropriately selected according to the battery dimensions and intended use.

[0092] The secondary battery according to this embodiment can be used in various forms such as prismatic, cylindrical, flat, thin, and coin-type. The secondary battery may also be a secondary battery having a bipolar structure. For example, the electrode group may have a bipolar structure in which a positive electrode active material-containing layer is provided on one side of a current collector and a negative electrode active material-containing layer is provided on the other side. In this case, there is an advantage that multiple series-connected cells can be manufactured from a single cell.

[0093] The following describes how to verify the positive electrode active material, negative electrode active material, negative electrode binder, and aqueous electrolyte.

[0094] If the battery contains both a positive and negative electrode, the battery must be disassembled to remove the positive or negative electrode, and then cleaned with dimethyl carbonate (DMC). The cleaning method is described below. Immerse the electrode (positive or negative electrode) in DMC for 5 minutes, then remove the electrode. Repeat this process three times, dry the electrode, and then use it for measurement. Use fresh DMC each time you repeat the immersion process.

[0095] When extracting aqueous electrolytes from a battery, the battery is disassembled, and if aqueous electrolytes are present outside the electrodes, the aqueous electrolytes not impregnated by the electrodes are collected. If aqueous electrolytes cannot be collected from outside the electrodes, the electrode group is placed in a centrifuge, and the aqueous electrolytes are collected by centrifugation. <Cathode active material> The crystal structure and elemental composition of the positive electrode active material can be confirmed by powder X-ray diffraction (XRD) and inductively coupled plasma (ICP) emission spectroscopy. <Negative electrode active material> The crystal structure and elemental composition of the negative electrode active material can be confirmed by powder X-ray diffraction (XRD) and inductively coupled plasma (ICP) emission spectroscopy. <Negative electrode binder> The composition of the binder contained in the negative electrode can be confirmed by GC-MS (Gas Chromatography-Mass Spectrometry) measurement.

[0096] W bindThe measurement is carried out by the following method. Disassemble the battery and collect the negative electrode. Next, cut out a part of this negative electrode to obtain a test piece. The size of the test piece is, for example, a square plate with a side length of 2 cm. The test piece is washed in advance with, for example, dimethyl carbonate (DMC) and then vacuum dried at 80 °C. After drying, collect the active material-containing layer from the current collector of the test piece and perform thermal gravimetric analysis (TG). The weight loss up to 600 °C is regarded as the binder weight. Calculate the ratio (weight %) of the binder weight to the weight of the active material-containing layer contained in the test piece from the obtained binder weight and the weight of the active material-containing layer of the test piece to obtain W bind to obtain. <XPS analysis> Whether or not a nitrogen-containing compound is present on the surface of the negative electrode can be confirmed by XPS analysis under the conditions described below.

[0097] As the XPS apparatus, Quantera SXM manufactured by ULVAC-PHI, Inc., or an apparatus having an equivalent function can be used. For the excitation X-ray source, a single crystal spectroscopic Al-Kα ray (1486.6 eV) is used. The X-ray output is 4 kW (13 kV × 310 mA), the photoelectron detection angle is 45°, and the analysis region is about 4 mm × 0.2 mm. The scan is performed at 0.10 eV / step. <Aqueous electrolyte> That water is contained in the aqueous electrolyte can be confirmed by GC-MS (Gas Chromatography-Mass Spectrometry) measurement. Also, the water content W H2O in the aqueous electrolyte can be measured, for example, by evaporating the water in the aqueous electrolyte and measuring the weight ratio of the aqueous electrolyte to the residue. Weigh a specified amount of the aqueous electrolyte and evaporate the aqueous electrolyte in an inert atmosphere. Calculate the water content W H2O from the weight ratio to the residue.

[0098] The presence of compounds containing amide bonds in aqueous electrolytes can be confirmed as follows: First, the presence of nitrogen-containing compounds in the aqueous electrolyte is confirmed using inductively coupled plasma emission spectroscopy (ICP). Then, the electrolyte is subjected to infrared spectroscopy, for example, at 1550-1700 cm⁻¹. -1 If a peak is present, it indicates that the electrolyte contains a nitrogen-containing compound, thus confirming that the electrolyte contains a compound with an amide bond.

[0099] An example of applying the battery of the embodiment to a secondary battery will be explained with reference to Figures 1 to 4.

[0100] The secondary battery 1 includes an electrode group 2 and an outer casing member 20 that houses the electrode group 2. The electrode group 2 is housed within the outer casing member 20, which is a rectangular cylindrical metal container. The electrode group 2 includes a negative electrode 3, a separator 4, and a positive electrode 5. The electrode group 2 has a structure in which the material is wound in a spiral shape with the separator 4 interposed between the positive electrode 5 and the negative electrode 3 to form a flattened shape. An aqueous electrolyte (not shown) is held in the electrode group 2. As shown in Figure 2, multiple strip-shaped negative electrode leads 16 are electrically connected to each of the multiple ends of the negative electrode 3 located on the end face of the electrode group 2. Similarly, multiple strip-shaped positive electrode leads 17 are electrically connected to each of the multiple ends of the positive electrode 5 located on the same end face. These multiple negative electrode leads 16 are bundled together and connected to the negative electrode terminal 6, as shown in Figure 2. Although not shown, the positive electrode leads 17 are similarly bundled together and electrically connected to the positive electrode terminal 7.

[0101] The metal sealing plate 21 is fixed to the opening of the metal exterior member 20 by welding or the like. The negative terminal 6 and positive terminal 7 are each led out to the outside through outlet holes provided in the sealing plate 21. A negative terminal gasket 8 and a positive terminal gasket 9 are placed on the inner circumferential surface of each outlet hole in the sealing plate 21, respectively, to prevent short circuits caused by contact with the negative terminal 6 and positive terminal 7. By placing the negative terminal gasket 8 and the positive terminal gasket 9, the airtightness of the secondary battery 100 can be maintained.

[0102] A control valve 22 (safety valve) is positioned on the sealing plate 21. If the internal pressure in the battery cell increases due to gas generated inside the outer casing member 20, the control valve 22 can release the generated gas to the outside. As the control valve 22, for example, a reset type can be used that operates when the internal pressure exceeds a set value and functions as a sealing plug when the internal pressure decreases. Alternatively, a non-resettable control valve that does not recover its function as a sealing plug once activated may be used. In Figure 1, the control valve 22 is positioned in the center of the sealing plate 21, but the position of the control valve 22 may also be at the edge of the sealing plate 21. Note that the control valve 22 may be omitted.

[0103] Furthermore, the sealing plate 21 is provided with an injection port 23. The electrolyte can be injected through this injection port 23. After the electrolyte has been injected, the injection port 23 can be sealed with a sealing plug 24. The injection port 23 and the sealing plug 24 may be omitted.

[0104] Another example of a secondary battery will be described with reference to Figures 3 and 4. Figures 3 and 4 show an example of a secondary battery 1 using a laminate film outer casing as the container.

[0105] The secondary battery 1 shown in Figures 3 and 4 comprises an electrode group 2 shown in Figures 3 and 4, an outer casing member 20 shown in Figure 3, and an electrolyte (not shown). The electrode group 2 and the electrolyte are housed within the outer casing member 20. The electrolyte is held within the electrode group 2.

[0106] The exterior component 20 consists of a laminate film comprising two resin layers and a metal layer interposed between them.

[0107] As shown in Figure 4, electrode group 2 is a stacked electrode group. The stacked electrode group 2 has a structure in which negative electrodes 3 and positive electrodes 5 are alternately stacked with separators 4 interposed between them.

[0108] The electrode group 2 includes a plurality of negative electrodes 3. Each of the plurality of negative electrodes 3 comprises a negative electrode current collector 3a and a negative electrode active material-containing layer 3b supported on both sides of the negative electrode current collector 3a. The electrode group 2 also includes a plurality of positive electrodes 5. Each of the plurality of positive electrodes 5 comprises a positive electrode current collector 5a and a positive electrode active material-containing layer 5b supported on both sides of the positive electrode current collector 5a.

[0109] Each negative electrode 3's negative electrode current collector 3a includes a portion 3c on one side where the negative electrode active material-containing layer 3b is not supported on any surface. This portion 3c functions as a negative electrode current collector tab. As shown in Figure 4, the portion 3c acting as a negative electrode current collector tab does not overlap with the positive electrode 5. Furthermore, multiple negative electrode current collector tabs (portions 3c) are electrically connected to a strip-shaped negative electrode terminal 6. The tip of the strip-shaped negative electrode terminal 6 is extended to the outside of the outer casing member 20.

[0110] Although not shown in the diagram, the positive electrode current collector 5a of each positive electrode 5 includes a portion on one side where the positive electrode active material-containing layer 5b is not supported on any surface. This portion functions as a positive electrode current collector tab. The positive electrode current collector tab, like the negative electrode current collector tab (part 3c), does not overlap with the negative electrode 3. Furthermore, the positive electrode current collector tab is located on the opposite side of the electrode group 2 from the negative electrode current collector tab (part 3c). The positive electrode current collector tab is electrically connected to a strip-shaped positive electrode terminal 7. The tip of the strip-shaped positive electrode terminal 7 is located on the opposite side from the negative electrode terminal 6 and is extended to the outside of the outer casing member 20.

[0111] The battery according to the embodiment described above includes a positive electrode, a negative electrode, and an electrolyte containing water. The negative electrode includes a negative electrode active material containing a Ti-containing oxide and a water-containing binder. The battery also satisfies equation (1).

[0112] 0.2 ≤ W bind / W H2O ≤15 (1) However, W bind This is the content (by weight) of the water-containing binder in the negative electrode active material layer, W H2O This represents the water content (by weight) in the electrolyte.

[0113] According to the above-described battery, the electrolysis of water can be suppressed, and the adhesion between the active material-containing layer and the current collector, as well as the retention of the aqueous electrolyte in the active material-containing layer, can be improved. Therefore, the battery of this embodiment can improve charge-discharge cycle performance.

[0114] (Second Embodiment) According to the second embodiment, a battery pack is provided. The battery pack comprises a plurality of secondary batteries according to the embodiment.

[0115] In the battery pack according to this embodiment, each individual cell may be arranged in series or parallel connections, or a combination of series and parallel connections may be used.

[0116] Next, we will explain an example of a battery pack, referring to the diagram.

[0117] The battery pack 200 shown in Figure 5 comprises five single cells 100a to 100e, four busbars 201, a positive electrode lead 207, and a negative electrode lead 206. Each of the five single cells 100a to 100e is a secondary battery according to the embodiment.

[0118] The busbar 201 connects, for example, the negative terminal 6 of one cell 100a to the positive terminal 7 of the adjacent cell 100b. In this way, the five cells 100 are connected in series by four busbars 201. That is, the battery pack 200 in Figure 5 is a battery pack with five cells in series. Although not illustrated, in a battery pack containing multiple cells that are electrically connected in parallel, the multiple cells can be electrically connected, for example, by connecting multiple negative terminals to each other and multiple positive terminals to each other by busbars.

[0119] The positive terminal 7 of at least one of the five single cells 100a to 100e is electrically connected to the positive lead 207 for external connection. In addition, the negative terminal 6 of at least one of the five single cells 100a to 100e is electrically connected to the negative lead 206 for external connection.

[0120] The battery pack according to this embodiment comprises the battery according to this embodiment. Therefore, the battery pack can have excellent lifespan performance.

[0121] [Third Embodiment] According to the third embodiment, a battery pack including a battery according to the embodiment is provided. This battery pack may comprise a battery pack according to the embodiment. This battery pack may comprise a single battery instead of a battery pack according to the embodiment.

[0122] The battery pack may further include a protection circuit. The protection circuit has the function of controlling the charging and discharging of the secondary battery. Alternatively, a circuit included in a device that uses the battery pack as a power source (e.g., electronic equipment, automobile, etc.) may be used as the protection circuit for the battery pack.

[0123] Furthermore, the battery pack may also be equipped with external terminals for power supply. These external terminals are for outputting current from the secondary battery to the outside and / or for inputting current from an outside to the secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through the external terminals. Also, when charging the battery pack, the charging current (including regenerative energy from the power of an automobile, etc.) is supplied to the battery pack through the external terminals.

[0124] Next, an example of a battery pack according to the embodiment will be described with reference to the drawings.

[0125] The battery pack 300 shown in Figures 6 and 7 comprises a housing 31, a lid 32, a protective sheet 33, a battery pack 200, a printed circuit board 34, wiring 35, and an insulating plate (not shown).

[0126] The container 31 shown in Figure 6 is a bottomed rectangular container with a rectangular base. The container 31 is configured to accommodate a protective sheet 33, a battery pack 200, a printed circuit board 34, and wiring 35. The lid 32 has a rectangular shape. The lid 32 covers the container 31, thereby housing the battery pack 200 and the other components. The container 31 and the lid 32 are provided with openings or connection terminals for connecting to external devices, etc., although these are not shown in the figures.

[0127] The battery pack 200 comprises multiple individual cells 100, a positive electrode lead 207, a negative electrode lead 206, and an adhesive tape 36.

[0128] At least one of the multiple single cells 100 is a secondary battery according to the embodiment. Each of the multiple single cells 100 is electrically connected in series as shown in Figure 7. The multiple single cells 100 may also be electrically connected in parallel, or they may be connected in a combination of series and parallel connections. When the multiple single cells 100 are connected in parallel, the battery capacity increases compared to when they are connected in series.

[0129] The adhesive tape 36 fastens multiple single cells 100 together. Alternatively, heat-shrinkable tape may be used to secure the multiple single cells 100 instead of the adhesive tape 36. In this case, protective sheets 33 are placed on both sides of the battery pack 200, the heat-shrinkable tape is wrapped around it, and then the heat-shrinkable tape is heat-shrinked to bundle the multiple single cells 100 together.

[0130] One end of the positive lead 207 is connected to the battery pack 200. One end of the positive lead 207 is electrically connected to the positive terminal of one or more single cells 100. One end of the negative lead 206 is connected to the battery pack 200. One end of the negative lead 206 is electrically connected to the negative terminal of one or more single cells 100.

[0131] The printed circuit board 34 is installed along one of the shorter sides of the inner surface of the housing container 31. The printed circuit board 34 includes a positive terminal connector 342, a negative terminal connector 343, a thermistor 345, a protection circuit 346, wiring 342a and 343a, an external terminal 350 for energization, a positive side wiring (positive wiring) 348a, and a negative side wiring (negative wiring) 348b. One main surface of the printed circuit board 34 faces one side of the battery pack 200. An insulating plate (not shown) is interposed between the printed circuit board 34 and the battery pack 200.

[0132] The other end 207a of the positive lead 207 is electrically connected to the positive connector 342. The other end 206a of the negative lead 206 is electrically connected to the negative connector 343.

[0133] The thermistor 345 is fixed to one main surface of the printed circuit board 34. The thermistor 345 detects the temperature of each of the single cells 100 and transmits the detection signal to the protection circuit 346.

[0134] The external power supply terminal 350 is fixed to the other main surface of the printed circuit board 34. The external power supply terminal 350 is electrically connected to equipment located outside the battery pack 300. The external power supply terminal 350 includes a positive terminal 352 and a negative terminal 353.

[0135] The protection circuit 346 is fixed to the other main surface of the printed circuit board 34. The protection circuit 346 is connected to the positive terminal 352 via the positive side wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via the negative side wiring 348b. The protection circuit 346 is also electrically connected to the positive side connector 342 via wiring 342a. The protection circuit 346 is also electrically connected to the negative side connector 343 via wiring 343a. Furthermore, the protection circuit 346 is electrically connected to each of the multiple single cells 100 via wiring 35.

[0136] The protective sheet 33 is positioned on both inner surfaces in the long-side direction of the housing container 31 and on the inner surface in the short-side direction facing the printed circuit board 34 via the battery pack 200. The protective sheet 33 is made of, for example, resin or rubber.

[0137] The protection circuit 346 controls the charging and discharging of multiple single cells 100. The protection circuit 346 also disconnects the electrical connection between the protection circuit 346 and the external terminals 350 (positive terminal 352, negative terminal 353) for supplying power to external devices, based on a detection signal transmitted from the thermistor 345 or a detection signal transmitted from an individual single cell 100 or a battery pack 200.

[0138] An example of a detection signal transmitted from the thermistor 345 is a signal indicating that the temperature of a single cell 100 is above a predetermined temperature. An example of a detection signal transmitted from an individual single cell 100 or a battery pack 200 is a signal indicating that overcharging, over-discharging, or overcurrent has been detected in a single cell 100. When detecting overcharging, etc., in an individual single cell 100, the battery voltage may be detected, or the positive electrode potential or negative electrode potential may be detected. In the latter case, a lithium electrode to be used as a reference electrode is inserted into each individual single cell 100.

[0139] Furthermore, the protection circuit 346 may be a circuit included in a device that uses the battery pack 300 as a power source (for example, an electronic device, an automobile, etc.).

[0140] Furthermore, as described above, the battery pack 300 is equipped with an external terminal 350 for power supply. Therefore, the battery pack 300 can output current from the battery pack 200 to an external device and input current from an external device to the battery pack 200 via the external terminal 350. In other words, when the battery pack 300 is used as a power source, current from the battery pack 200 is supplied to the external device through the external terminal 350. Also, when charging the battery pack 300, charging current from an external device is supplied to the battery pack 300 through the external terminal 350. When this battery pack 300 is used as an on-board battery, the regenerative energy of the vehicle's power can be used as the charging current from the external device.

[0141] The battery pack 300 may comprise multiple battery packs 200. In this case, the multiple battery packs 200 may be connected in series, in parallel, or in a combination of series and parallel connections. The printed circuit board 34 and wiring 35 may also be omitted. In this case, the positive lead 207 and the negative lead 206 may be used as the positive and negative terminals of the external terminals for energization, respectively.

[0142] Such battery packs are used in applications where excellent cycle performance is required, for example, when drawing high currents. Specifically, these battery packs are used as power supplies for electronic devices, stationary batteries, and on-board batteries for various vehicles. Examples of electronic devices include digital cameras. These battery packs are particularly suitable for use as on-board batteries.

[0143] The battery pack according to the third embodiment comprises a battery or a battery pack according to the embodiment. Therefore, the battery pack has excellent lifespan performance.

[0144] [Fourth Embodiment] According to the fourth embodiment, a vehicle including a battery pack according to the embodiment is provided.

[0145] In such a vehicle, the battery pack, for example, recovers regenerative energy from the vehicle's power. The vehicle may also include a mechanism (regenerator) that converts the vehicle's kinetic energy into regenerative energy.

[0146] Examples of vehicles according to this embodiment include, for example, two-wheeled to four-wheeled hybrid electric vehicles, two-wheeled to four-wheeled electric vehicles, electric assist bicycles, and railway vehicles.

[0147] The mounting location of the battery pack in the vehicle according to the embodiment is not particularly limited. For example, when the battery pack is mounted in an automobile, it can be mounted in the engine compartment, at the rear of the vehicle, or under the seats.

[0148] The vehicle according to this embodiment may be equipped with multiple battery packs. In this case, the batteries contained in each battery pack may be electrically connected in series, electrically connected in parallel, or electrically connected in a combination of series and parallel connections. For example, if each battery pack contains a battery pack, the battery packs may be electrically connected in series, electrically connected in parallel, or electrically connected in a combination of series and parallel connections. Alternatively, if each battery pack contains a single battery, the batteries may be electrically connected in series, electrically connected in parallel, or electrically connected in a combination of series and parallel connections.

[0149] Next, an example of a vehicle according to the embodiment will be described with reference to the drawings.

[0150] The vehicle 400 shown in Figure 8 includes a vehicle body 40 and a battery pack 300 according to this embodiment. In the example shown in Figure 8, the vehicle 400 is a four-wheeled automobile.

[0151] This vehicle 400 may be equipped with multiple battery packs 300. In this case, the batteries contained in the battery pack 300 (for example, single cells or battery packs) may be connected in series, in parallel, or in a combination of series and parallel connections.

[0152] Figure 8 illustrates an example in which the battery pack 300 is mounted in the engine compartment located in front of the vehicle body 40. As described above, the battery pack 300 may also be mounted, for example, in the rear of the vehicle body 40 or under the seats. This battery pack 300 can be used as a power source for the vehicle 400. In addition, this battery pack 300 can recover regenerative energy from the vehicle 400's power.

[0153] The vehicle according to the fourth embodiment is equipped with a battery pack according to the embodiment. Therefore, the vehicle can exhibit high performance and high reliability.

[0154] [Fifth Embodiment] According to the fifth embodiment, a stationary power supply including a battery pack according to the embodiment is provided.

[0155] The stationary power supply may be equipped with a battery pack or a battery according to the embodiment instead of the battery pack according to the embodiment. The stationary power supply can exhibit a long lifespan.

[0156] Figure 9 shows an example of the application of the battery packs 300A and 300B according to the embodiment to stationary power supplies 112 and 123. In the example shown in Figure 9, a system 110 is shown in which the stationary power supplies 112 and 123 are used. The system 110 comprises a power plant 111, a stationary power supply 112, a consumer-side power grid 113, and an energy management system (EMS) 115. A power grid 116 and a communication network 117 are also formed within the system 110, and the power plant 111, the stationary power supply 112, the consumer-side power grid 113, and the EMS 115 are connected via the power grid 116 and the communication network 117. The EMS 115 utilizes the power grid 116 and the communication network 117 to perform control to stabilize the entire system 110.

[0157] Power plant 111 generates a large amount of electricity using fuel sources such as thermal and nuclear power. Electricity is supplied from power plant 111 through the power grid 116, etc. A battery pack 300A is installed in stationary power supply 112. The battery pack 300A can store electricity supplied from power plant 111, etc. The stationary power supply 112 can also supply the electricity stored in the battery pack 300A through the power grid 116, etc. System 110 is equipped with a power converter 118. The power converter 118 includes a converter, inverter, and transformer, etc. Therefore, the power converter 118 can perform conversion between DC and AC, conversion between ACs with different frequencies relative to each other, and voltage transformation (boost and step down). For this reason, the power converter 118 can convert the electricity from power plant 111 into electricity that can be stored in the battery pack 300A.

[0158] The consumer-side power system 113 includes power systems for factories, buildings, and households. The consumer-side power system 113 is equipped with a consumer-side EMS 121, a power converter 122, and a stationary power supply 123. The stationary power supply 123 is fitted with a battery pack 300B. The consumer-side EMS 121 performs control to stabilize the consumer-side power system 113.

[0159] The consumer-side power grid 113 is supplied with power from the power plant 111 and power from the battery pack 300A via the power grid 116. The battery pack 300B can store the power supplied to the consumer-side power grid 113. The power converter 122, like the power converter 118, includes a converter, inverter, and transformer. Therefore, the power converter 122 can perform conversions between DC and AC, conversions between ACs with different frequencies, and voltage transformations (boost and step down). Thus, the power converter 122 can convert the power supplied to the consumer-side power grid 113 into power that can be stored in the battery pack 300B.

[0160] The electricity stored in the battery pack 300B can be used, for example, to charge vehicles such as electric cars. Furthermore, the system 110 may be equipped with a renewable energy source. In this case, the renewable energy source generates electricity using natural energy sources such as wind and solar power. Electricity is then supplied from both the power plant 111 and the renewable energy source through the power grid 116. [Examples]

[0161] The above embodiments will be described in detail below with reference to examples, but the present invention is not limited to the following embodiments without departing from the spirit of the invention.

[0162] (Example 1) A secondary battery was manufactured using the following procedure.

[0163] <Fabrication of the negative electrode> As the negative electrode active material, we prepared particles of a monoclinic niobium-titanium oxide containing a composition represented by the formula TiNb2O7. This monoclinic niobium-titanium oxide is used in batteries, Li a The composition is represented by TiNb2O7 (0≦a≦5). Acetylene black was prepared as a conductive agent, and carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) were prepared as water-containing binders. These were mixed in pure water in a weight ratio (wt%) of negative electrode active material:acetylene black:carboxymethylcellulose:styrene-butadiene rubber of 95:4.2:0.4:0.4 to obtain a slurry. This slurry was applied to a current collector made of aluminum foil with a thickness of 15 μm, and the coating was dried. Thus, a composite was obtained containing the current collector and a negative electrode active material-containing layer formed on the current collector. Next, the obtained composite was subjected to a roll press. Then, this composite was further subjected to vacuum drying to obtain a negative electrode.

[0164] <Fabrication of the positive electrode> As the positive electrode active material, Formula LiNi 0.33 Mn 0.33 Co 0.33Particles of lithium nickel cobalt manganese composite oxide represented as O2 (referred to as NMC111) were prepared. Acetylene black was prepared as a conductive agent, and polyvinylidene fluoride (PVdF) was prepared as a binder. These were mixed in a weight ratio (wt%) of positive electrode active material:conductive agent:binder of 90:5:5 to obtain a mixture. Next, the obtained mixture was dispersed in n-methylpyrrolidone (NMP) solvent to prepare a positive electrode slurry. This slurry was applied to a current collector made of aluminum foil with a thickness of 15 μm, and the coating was dried. Thus, a composite was obtained containing a current collector and positive electrode active material-containing layers formed on both sides of the current collector. Next, the obtained composite was subjected to a roll press. Then, this composite was further subjected to vacuum drying to obtain a positive electrode.

[0165] The positive and negative electrodes were cut out so that the area of ​​the active material-containing layer was 3 cm wide and 5 cm high. An electrode laminate was fabricated by bonding one negative electrode and one positive electrode together with a 30 μm thick cellulose separator in between. In addition, 0.2 mm thick aluminum tabs were attached to the negative and positive electrodes for current collection. The fabricated electrode laminate was housed in an outer casing made of laminate film, and after pouring in a liquid aqueous electrolyte (aqueous electrolyte solution), it was sealed to obtain a secondary battery.

[0166] The liquid aqueous electrolyte had a composition consisting of 56.0% by weight of LiN(CF3SO2)2(LiTFSI), 39.8% by weight of urea, 0.2% by weight of KOH, and 4% by weight of H2O.

[0167] (Example 2) The negative electrode was prepared in the same manner as in Example 1, except that the weight ratio (weight %) of the negative electrode active material (acetylene black:CMC:SBR) was set to 92.5:4.0:1.5:2.0.

[0168] Furthermore, the composition of the liquid aqueous electrolyte was changed to one consisting of 56.0% by weight of LiN(CF3SO2)2(LiTFSI), 40.4% by weight of urea, 0.1% by weight of KOH, and 3.5% by weight of H2O.

[0169] Aside from these, the secondary battery was fabricated in the same manner as in Example 1.

[0170] (Example 3) The negative electrode was prepared in the same manner as in Example 1, except that the weight ratio (weight %) of the negative electrode active material (acetylene black:CMC:SBR) was set to 91.5:4.0:2.0:2.5.

[0171] Furthermore, the composition of the liquid aqueous electrolyte was changed to one consisting of 58.2% by weight of LiN(CF3SO2)2(LiTFSI), 41.3% by weight of urea, 0.2% by weight of KOH, and 0.3% by weight of H2O.

[0172] Aside from these, the secondary battery was fabricated in the same manner as in Example 1.

[0173] (Examples 4-7) The negative electrode was prepared in the same manner as in Example 2, except that the composition of the negative electrode active material was changed to the composition shown in Table 1. The secondary battery was prepared in the same manner as in Example 2, except that this negative electrode was used. Note that the negative electrode active material in Example 4 is Li in the battery. a Ti2Nb 10 O 29 It has a composition represented by (0≦a≦22). The negative electrode active material of Example 5 is Li in a battery. a The composition is represented by Ti2Nb2O9 (0≦a≦6). The negative electrode active materials of Examples 6 and 7 are, respectively, Li in a battery. x It has a composition represented by TiO2 (where x is 0 ≤ x ≤ 1).

[0174] (Example 8) The composition of the liquid aqueous electrolyte was changed to one consisting of 55.9% by weight of LiN(CF3SO2)2(LiTFSI), 40.5% by weight of acetamide, 0.1% by weight of KOH, and 3.5% by weight of H2O. A secondary battery was fabricated in the same manner as in Example 2, except for the use of this liquid aqueous electrolyte.

[0175] (Example 9) Polyvinylpyrrolidone (PVP) and styrene-butadiene rubber (SBR) were prepared as water-containing binders. The negative electrode was prepared in the same manner as in Example 1, except that these were blended so that the weight ratio (wt%) of negative electrode active material:acetylene black:PVP:SBR was 92.5:4.0:1.8:1.7.

[0176] The composition of the liquid aqueous electrolyte was changed to one consisting of 51.3% by weight of LiN(CF3SO2)2(LiTFSI), 45.0% by weight of N-methylurea, 0.2% by weight of KOH, and 3.5% by weight of H2O. A secondary battery was fabricated in the same manner as in Example 1, except for the use of the above-mentioned negative electrode and liquid aqueous electrolyte.

[0177] (Example 10) LiNi 0.8 Mn 0.1 Co 0.1 The positive electrode was fabricated in the same manner as in Example 1, except that particles of lithium nickel cobalt manganese composite oxide represented as O2 (referred to as NMC811) were used.

[0178] Furthermore, the composition of the liquid aqueous electrolyte was changed to consist of 54.0 wt% LiN(CF3SO2)2(LiTFSI), 2.0 wt% lithium difluorooxalatoborate (LiDFOB), 40.4 wt% urea, 0.1 wt% KOH, and 3.5 wt% H2O. A secondary battery was fabricated in the same manner as in Example 2, except for the use of the above-mentioned positive electrode and liquid aqueous electrolyte.

[0179] (Example 11) Li with a spinel structure as the positive electrode active material 1.05 Al 0.05 A positive electrode was fabricated in the same manner as in Example 1, except that particles of lithium manganese composite oxide represented as Mn2O4 (referred to as LMO) were used. A secondary battery was fabricated in the same manner as in Example 2, except that this positive electrode was used.

[0180] (Example 12) Li with a spinel structure as the positive electrode active material 1.05 Al 0.05The positive electrode was prepared in the same manner as in Example 1, except that particles of lithium manganese composite oxide represented as Mn2O4 (referred to as LMO) were used.

[0181] The composition of the liquid aqueous electrolyte was changed to one consisting of 57.7% by weight of LiN(CF3SO2)2(LiTFSI), 41.1% by weight of urea, 0.2% by weight of KOH, and 1.0% by weight of H2O.

[0182] A secondary battery was fabricated in the same manner as in Example 2, except that the above-mentioned positive electrode and liquid aqueous electrolyte were used.

[0183] (Example 13) Li with a spinel structure as the positive electrode active material 1.05 Al 0.05 The positive electrode was prepared in the same manner as in Example 1, except that particles of lithium manganese composite oxide represented as Mn2O4 (referred to as LMO) were used.

[0184] The negative electrode was prepared in the same manner as in Example 1, except that the weight ratio (weight %) of the negative electrode active material (acetylene black:CMC:SBR) was set to 92:4.0:2.0:2.0.

[0185] Furthermore, the composition of the liquid aqueous electrolyte was changed to one consisting of 53.7% by weight of LiN(CF3SO2)2(LiTFSI), 38.1% by weight of urea, 0.2% by weight of KOH, and 8.0% by weight of H2O.

[0186] A secondary battery was prepared in the same manner as in Example 1, except that the positive electrode, negative electrode, and liquid aqueous electrolyte described above were used.

[0187] (Comparative Example 1) The composition of the liquid aqueous electrolyte was changed to one consisting of 53.7% by weight of LiN(CF3SO2)2(LiTFSI), 38.1% by weight of urea, 0.2% by weight of KOH, and 8.0% by weight of H2O. A secondary battery was fabricated in the same manner as in Example 1, except for the use of this liquid aqueous electrolyte.

[0188] (Comparative Example 2) The negative electrode was prepared in the same manner as in Example 1, except that the weight ratio (weight %) of the negative electrode active material (acetylene black:CMC:SBR) was set to 90:4.0:2.0:4.0.

[0189] Furthermore, the composition of the liquid aqueous electrolyte was changed to one consisting of 58.2% by weight of LiN(CF3SO2)2(LiTFSI), 41.3% by weight of urea, 0.2% by weight of KOH, and 0.3% by weight of H2O.

[0190] A secondary battery was fabricated in the same manner as in Example 1, except that the negative electrode and liquid aqueous electrolyte described above were used.

[0191] (Comparative Example 3) As the negative electrode active material, particles of niobium titanium-containing oxide with a monoclinic structure having the same composition as in Example 1 were prepared. Acetylene black as a conductive agent and polyvinylidene fluoride (PVdF) as a binder were also prepared. These were mixed in n-methylpyrrolidone (NMP) in a weight ratio (wt%) of negative electrode active material:acetylene black:PVdF of 94:4.0:2.0 to obtain a slurry. This slurry was applied to a current collector made of aluminum foil with a thickness of 15 μm, and the coating was dried. Thus, a composite was obtained containing the current collector and the negative electrode active material-containing layer formed on the current collector. Next, the obtained composite was subjected to a roll press. Then, this composite was further subjected to vacuum drying to obtain the negative electrode.

[0192] A secondary battery was fabricated in the same manner as in Example 2, except that the above-mentioned negative electrode was used. <Rating> The secondary batteries obtained in the above examples and comparative examples underwent their initial charge-discharge cycle, and their charge-discharge cycle life was measured at 25°C. At 25°C, the batteries were charged to 2.6V at 0.2C and then discharged to 1.5V at 0.2C. This charge-discharge cycle was repeated 50 times, and the retention rate (%) of the discharge capacity at the 50th cycle relative to the discharge capacity at the 1st cycle was calculated and is shown in Table 3 as the capacity retention rate during the charge-discharge cycle.

[0193] Table 1 shows the composition of the negative electrode active material, the composition of the positive electrode active material, and the amount of water-containing binder in the negative electrode active material layer. bind (weight %), water content in electrolyte W H2O (wt%), W bind / W H2O The value of the ratio represented by W is shown. bind (weight %) and W H2O The measurement method (by weight %) is as described above. Table 2 shows the type of binder used for the negative electrode and the composition of the aqueous electrolyte.

[0194] [Table 1]

[0195] [Table 2]

[0196] [Table 3]

[0197] As is clear from Tables 1 to 3, 0.2 ≤ W bind / W H2O The secondary batteries of Examples 1 to 13 that satisfy ≤15 have a charge-discharge cycle life that is superior to that of Comparative Examples 1 to 3. Comparative Examples 1 and 2 use a water-containing binder, but W bind / W H2O The ratio value expressed by does not meet the above range. On the other hand, in Comparative Example 3, PVdF was used as a binder, so the PVdF decomposed due to the water in the electrolyte, and the negative electrode active material-containing layer peeled off from the current collector. As a result, the charge-discharge cycle life of the battery in Comparative Example 3 was shorter than that of Examples 1 to 13.

[0198] By comparing Example 2 with Examples 4-7, Li a TiM b Nb 2±β O 7±σThe charge-discharge cycle life of the battery of Example 2 containing a monoclinic niobium titanium-containing oxide represented by (0 ≤ a ≤ 5, 0 ≤ b ≤ 0.3, 0 ≤ β ≤ 0.3, 0 ≤ σ ≤ 0.3, and M is at least one element selected from the group consisting of Fe, V, Mo, and Ta) as a negative electrode active material is found to be superior to those of Examples 4 to 7.

[0199] From the comparison between Example 2 and Examples 8 to 9, it can be seen that the charge-discharge cycle life of the battery of Example 2 containing urea as a compound containing an amide bond is superior to those of Examples 8 to 9.

[0200] According to the battery of at least one of these embodiments or examples, since the formula (1) is satisfied, the electrolysis of water can be suppressed and the life performance can be improved.

[0201] 0.2 ≤ W bind / W H2O ≤ 15 (1) However, W bind is the content (weight %) of the water-containing binder in the negative electrode active material-containing layer, and W H2O is the content (weight %) of water in the electrolyte.

[0202] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

[0203] Hereinafter, the invention of the embodiment will be appended. <1> A positive electrode, A negative electrode including a negative electrode active material-containing layer containing a Ti-containing oxide and a water-containing binder, An electrolyte containing water, and A battery that satisfies the following formula (1).

[0204] 0.2 ≤ W bind / W H2O ≤15 (1) However, W bind W is the content (by weight) of the water-containing binder in the negative electrode active material-containing layer. H2O This is the water content (by weight) in the electrolyte. <2> The aforementioned W H2O It is 10% by weight or less, and the W bind It is between 0.8% and 6% by weight. <1> The battery listed. <3> The aforementioned W H2O It is 0.3% by weight or more. <1> or <2> The battery listed. <4> The aqueous binder comprises at least one selected from the group consisting of carboxymethylcellulose and its salts, styrene-butadiene rubber, and polyvinylpyrrolidone. <1> from <3> A battery as described in any one of the items. <5> The electrolyte further comprises a compound containing an amide bond and at least one lithium salt selected from the group consisting of LiN(FSO2)2, LiN(CF3SO2)2, and LiN(SO2C2F5)2. <1> from <4> A battery as described in any one of the items. <6> The Ti-containing oxide comprises at least one of niobium-titanium-containing oxide or titanium oxide. <1> from <5> A battery as described in any one of the items. <7> The aforementioned Ti-containing oxides are TiNb2O7, Ti2Nb2O9, and Ti2Nb 10 O 29 TiNb 14 O 37 and TiNb 24 O 62 It includes at least one selected from the group consisting of niobium titanium-containing oxides containing at least one crystalline phase selected from the group consisting of monoclinic titanium oxides, rutile titanium oxides, and anatase titanium oxides, <1> from <5> A battery as described in any one of the items. <8> The Ti-containing oxide includes at least one selected from the group consisting of monoclinic niobium-titanium-containing oxide, monoclinic titanium oxide, rutile-structured titanium oxide, and anatase-structured titanium oxide. <1> from <5> A battery as described in any one of the items. <9> <1> from <8> A battery pack comprising the batteries described in any one of the items. <10> It further includes an external terminal for power supply and a protection circuit. <9> The battery pack described above. <11> The device comprises a plurality of the aforementioned batteries, and the batteries are electrically connected in series, in parallel, or in a combination of series and parallel. <9> or <10> The battery pack described above. <12> <9> from <11> A vehicle equipped with a battery pack as described in any one of the items. <13> The mechanism includes a mechanism that converts the kinetic energy of the vehicle into regenerative energy. <12> The vehicles listed. <14> <9> from <11> A stationary power supply equipped with a battery pack as described in any one of the items. [Explanation of Symbols]

[0205] 1...Battery, 2...Electrode group, 3...Negative electrode, 3a...Negative electrode current collector, 3b...Negative electrode composite layer (Negative electrode active material containing layer), 4...Separator, 5...Positive electrode, 5a...Positive electrode current collector, 5b...Positive electrode composite layer (Positive electrode active material containing layer), 6...Negative electrode terminal, 7...Positive electrode terminal, 8...Negative electrode gasket, 9...Positive electrode gasket, 16...Negative electrode lead, 17...Positive electrode lead, 20...Outer casing, 21...Sealing plate, 22...Control valve, 23...Filling port, 24...Sealing plug, 31...Housing container, 32...Lid, 33...Protective sheet, 34...Printed circuit board, 35...Wiring, 36...Adhesive tape, 40...Vehicle body, 100...Secondary battery, 110...System, 111...Power plant, 112...Stationary power supply, 113...Consumer side Power system, 115…Energy management system, 116…Power grid, 117…Communication network, 118…Power converter, 121…Customer-side EMS, 122…Power converter, 123…Stationary power supply, 200…Battery pack, 201…Busbar, 206…Negative lead, 207…Positive lead, 300…Battery pack, 300A…Battery pack, 300B…Battery pack, 342…Positive connector, 342a…Wiring, 343…Negative connector, 343a…Wiring, 345…Thermistor, 346…Protection circuit, 348a…Positive wiring, 348b…Negative wiring, 350…External terminal for energization, 352…Positive terminal, 353…Negative terminal, 400…Vehicle.

Claims

1. Positive electrode and, The negative electrode comprises a negative electrode active material containing a Ti-containing oxide and a water-containing binder, wherein the water-containing binder is at least one selected from the group consisting of carboxymethylcellulose and its salts, styrene-butadiene rubber and polyvinylpyrrolidone. It contains an electrolyte that includes water, A battery that satisfies equation (1) below. 0.2≦W ｂｉｎｄ / W Ｈ２Ｏ ≦15 (1) However, W ｂｉｎｄ The content (by weight) of the water-containing binder in the negative electrode active material-containing layer is 0.8% by weight or more and 6% by weight or less, W Ｈ２Ｏ The water content (by weight) in the electrolyte is 10% by weight or less.

2. The aforementioned W Ｈ２Ｏ The battery according to claim 1, wherein is 0.3% by weight or more.

3. The electrolyte further includes a compound containing an amide bond and at least one lithium salt selected from the group consisting of LiN(FSO 2 ) 2 , LiN(CF 3 SO 2 ), 2 LiN(SO 2 C 2 F 5 ), 2 The battery according to claim 1.

4. The battery according to claim 1, wherein the Ti-containing oxide comprises at least one of niobium-titanium-containing oxide or titanium oxide.

5. The Ti-containing oxide is TiNb 2 O 7 Ti 2 Nb 2 O 9 Ti 2 Nb 10 O 29 TiNb 14 O 37 and TiNb 24 O 62 The battery according to claim 1, comprising at least one selected from the group consisting of a niobium titanium-containing oxide having at least one crystalline phase selected from the group consisting of a monoclinic titanium oxide, a rutile titanium oxide, and an anatase titanium oxide.

6. The battery according to claim 1, wherein the Ti-containing oxide includes at least one selected from the group consisting of monoclinic niobium-titanium-containing oxide, monoclinic titanium oxide, rutile titanium oxide, and anatase titanium oxide.

7. A battery comprising the battery described in any one of claims 1 to 6, A battery pack further including external terminals for power supply and a protection circuit.

8. The battery pack according to claim 7, comprising a plurality of the aforementioned batteries, wherein the batteries are electrically connected in series, parallel, or a combination of series and parallel.

9. A vehicle equipped with the battery pack described in claim 7.

10. The vehicle according to claim 9, further comprising a mechanism for converting the kinetic energy of the vehicle into regenerative energy and supplying it to the battery pack as a charging current through the external terminal for energization.

11. A stationary power supply comprising the battery pack described in claim 7.

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