Electrode, secondary battery, battery pack, vehicle, and stationary power source

Abstract

To provide an electrode capable of realizing a high-capacity secondary battery having excellent charge / discharge performance, a high-capacity secondary battery and battery pack, and a vehicle and stationary power source equipped with the battery pack.SOLUTION: There are provided a current collector has a first porosity of 70% or more and 90% or less, and an electrode including the current collector and an active material-containing portion and having a second porosity of 60% or more and 80% or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present invention relates to an electrode, a secondary battery, a battery pack, a vehicle, and a stationary power source. [Background technology]

[0002] In order to increase the capacity of secondary batteries, it has been proposed to thicken the electrodes by, for example, increasing the amount of active material applied to the current collector. However, increasing the amount applied reduces the porosity of the electrode, causing poor electrolyte impregnation and reducing charge / discharge performance. This results in the actual energy density being lower than the designed energy density. This has limited the capacity that can be increased. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-33891 A [Patent Document 2] JP 2011-154979 A [Patent Document 3] JP 2012-195182 A Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide an electrode capable of realizing a high-capacity secondary battery having excellent charge / discharge performance, a high-capacity secondary battery and battery pack, and a vehicle and stationary power source equipped with the battery pack. [Means for solving the problem]

[0005] The electrode of the embodiment includes a current collector and an active material-containing portion. The first porosity of the current collector is 70% or more and 90% or less, and the second porosity of the electrode is 60% or more and 80% or less. [Brief description of the drawings]

[0006] [Figure 1] FIG. 2 is a schematic diagram illustrating an example of a current collector in the electrode according to the embodiment. [Diagram 2] FIG. 2 is a schematic diagram illustrating an example of an electrode according to the embodiment. [Diagram 3] FIG. 4 is a schematic diagram illustrating another example of an electrode according to an embodiment. [Figure 4] FIG. 4 is a schematic diagram illustrating another example of an electrode according to an embodiment. [Diagram 5] FIG. 1 is a cross-sectional view illustrating an example of a secondary battery according to an embodiment. [Figure 6] 6 is a schematic cross-sectional view taken along line II-II of the secondary battery shown in FIG. 5. [Figure 7] FIG. 4 is a partially cutaway perspective view illustrating a secondary battery according to another embodiment of the present invention. [Figure 8] 8 is an enlarged cross-sectional view of a portion E of the secondary battery shown in FIG. 7. [Figure 9] FIG. 1 is a perspective view illustrating an example of a battery pack according to an embodiment. [Figure 10] FIG. 13 is an exploded perspective view illustrating a battery pack according to another embodiment of the present invention. [Figure 11] FIG. 11 is a block diagram showing an example of an electric circuit of the battery pack shown in FIG. [Figure 12] 1 is a partially see-through view illustrating an example of a vehicle according to an embodiment. [Figure 13] FIG. 1 is a block diagram showing an example of a system including a stationary power supply according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, the embodiments will be described with reference to the drawings. Note that the same reference numerals are used to designate common components throughout the embodiments, and duplicated descriptions will be omitted. Each figure is a schematic diagram for explaining the embodiments and for facilitating understanding thereof, and the shapes, dimensions, ratios, etc. may differ from those of the actual device, but these can be appropriately modified in design by taking into consideration the following explanation and known techniques.

[0008] (First embodiment) According to a first embodiment, an electrode is provided. The electrode includes a current collector and an active material-containing portion. The first porosity of the current collector is 70% or more and 90% or less, and the second porosity of the electrode is 60% or more and 80% or less. Here, the first porosity refers to the porosity of the current collector. The second porosity refers to the porosity of the electrode including the current collector and the active material-containing portion. The void refers to a space existing between members of the current collector or the electrode.

[0009] Since the first porosity is 70% or more and 90% or less, the specific surface area of ​​the current collector is large and the amount of active material that can be supported is increased, making it possible to provide an electrode that can realize a high-capacity secondary battery. Furthermore, the second porosity being 60% or more and 80% or less means that the porosity is high even in a state in which the active material is included, so that the electrolyte can be impregnated into the electrode. The electrolyte impregnates into the electrode and increases the reactivity with the active material supported by the current collector, making it possible to provide an electrode that can realize a secondary battery with excellent charge / discharge performance.

[0010] The electrode according to the embodiment will be described in detail below. The electrode according to the embodiment can be used as either a positive electrode or a negative electrode.

[0011] The electrode includes a current collector and an active material-containing portion. The active material-containing portion includes an active material.

[0012] <Current collector> The current collector preferably has a porosity of 70% or more and 90% or less, and preferably has voids on the surface and inside of the current collector. It is preferable that the voids in the current collector are ubiquitous.

[0013] The material of the current collector is, for example, a material that is electrochemically stable at a potential at which lithium (Li) or sodium (Na) is inserted and removed from the active material. For example, it is a metal or a composite material. When the current collector contains a metal, copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing one or more elements selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si, can be selected. When the current collector is a composite material, for example, a porous material obtained by mixing a fibrous conductive material such as carbon nanotubes with a resin and press-molding the mixture can be used. As the resin, polyethylene, polypropylene, polyethylene terephthalate, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, etc. can be used. The conductive material and the resin can be one type or two or more types.

[0014] The composite material can also be produced by, for example, electrospinning. This method can produce a current collector with a large specific surface area and high porosity. In addition, by further performing a carbonization process, it is possible to impart sufficient electrical conductivity.

[0015] When used as a battery electrode, the collector is preferably in the form of a sheet. The thickness is preferably between 1 mm and 50 mm. This allows the formation of a three-dimensional conductive path.

[0016] The internal structure of the current collector is preferably one in which the void ratio per unit volume of the current collector is high. For example, a sponge-like porous material or a material having a network structure can be used.

[0017] As the material having a network structure, for example, a mesh, nonwoven fabric, or a material having intertwined fibers such as steel wool can be used.

[0018] When the current collector contains metal fibers (hereinafter referred to as metal fibers), it is preferable that the current collector contains at least one metal selected from the group consisting of copper, nickel, aluminum, titanium, zinc, iron, and stainless steel. When a current collector containing metal fibers is used as a part of the positive electrode in a battery having an electrolyte containing water, it is preferable to select titanium, which has excellent corrosion resistance.

[0019] Fig. 1 shows a schematic diagram of metal fibers as an example of a current collector. The current collector 2 shown in Fig. 1 is made of metal fibers 2a, which are long, string-like fibers that cross and gather together three-dimensionally to form a sheet. The metal fibers 2a may cross each other multiple times, or they may not cross at all. The crossing of the metal fibers 2a forms voids 2c.

[0020] The fiber diameter of the metal fibers is preferably 1 μm or more and 100 μm or less, which increases the specific surface area of ​​the current collector and allows more active material to be supported, thereby improving the charge / discharge performance.

[0021] The first porosity is 70% or more and 90% or less. When the first porosity is within this range, the active material-containing portion can be supported while maintaining the current collecting performance.

[0022] The current collector may include a portion on its surface or in its voids where no active material-containing portion is formed, and this portion can function as a current collecting tab or a current collecting lead.

[0023] <Active material containing part> The active material-containing portion refers to a portion supported on a current collector and containing an active material. The active material-containing portion may contain a conductive agent and a binder. The active material-containing portion of the current collector may cover the surface of the current collector, but is preferably present throughout the current collector.

[0024] FIG. 2 is a schematic diagram showing an example of the relationship between the current collector of the electrode according to the embodiment and the active material-containing portion. In this figure, a case where the current collector contains metal fibers is described. The active material-containing portion 2b shown in FIG. 2 contains an active material (not shown), a binder (not shown), and a conductive agent (not shown). The active material-containing portion 2b is supported on the surface of the metal fibers 2a. The active material-containing portion 2b can also be supported so as to fill the portions where the metal fibers 2a cross each other or the voids 2c formed by the metal fibers 2a.

[0025] The current collector 2 may include a plurality of voids 2c formed by the metal fibers 2a and the active material-containing portions 2b, and the surface of the current collector 2 or the voids 2c may be impregnated with an electrolyte (not shown).

[0026] The second porosity including the current collector and the active material-containing portion is 60% or more and 80% or less. By having the second porosity in this range, even if a highly viscous electrolyte is used, the electrolyte can be impregnated into the inside of the electrode.

[0027] <Negative electrode active material> When the electrode according to the embodiment is used as a negative electrode, the active material-containing portion contains a negative electrode active material. The negative electrode active material contains a Ti-containing oxide. The Ti-containing oxide is a material that can adsorb Li ions (Li + ) can be absorbed and released. The Ti-containing oxide may be an oxide further containing Li, or an oxide not containing Li. The Ti-containing oxide not containing Li is prepared by adding lithium ions (Li) during the synthesis of the oxide or by the addition of lithium ions (Li) + Before the absorption / release reaction of lithium ions or the charge / discharge reaction occurs, the Ti-containing oxide does not contain Li. Due to the irreversible reaction that occurs during the lithium ion absorption / release reaction or the charge / discharge reaction, Li may remain in the Ti-containing oxide.

[0028] Examples of titanium-containing oxides include lithium titanium-containing oxides, niobium titanium-containing oxides, and titanium oxides. When at least one of the niobium titanium-containing oxide or the titanium oxide is used as the negative electrode active material, for example, a high electromotive force can be obtained by combining it with a lithium manganese composite oxide or a lithium nickel cobalt manganese composite oxide as the positive electrode active material. Further, since the lithium ion insertion / desorption reaction of the niobium titanium-containing oxide is a solid solution reaction, the operating potential of the electrode containing the niobium titanium-containing oxide has a width. For example, the operating potential of an electrode containing a niobium titanium-containing oxide containing a crystal phase represented by TiNb2O7 has a width from about 1.7 V to about 0.7 V. On the other hand, the operating potential of an electrode containing a lithium titanium-containing oxide such as 12 is constant at 1.55 V. Therefore, since the negative electrode containing the niobium titanium-containing oxide can set the negative electrode potential to a potential at which film formation is likely to occur, the formation of a nitrogen-containing compound in the negative electrode active material-containing portion can be promoted.

[0029] Examples of lithium titanium-containing oxides include lithium titanium oxides having a spinel structure (for example, general formula Li 4+x Ti5O 12 (x is -1 ≤ x ≤ 3)), lithium titanium oxides having a lamellar structure (for example, Li 2+x Ti3O7 (-1 ≤ x ≤ 3)), Li 1+x Ti2O4 (0 ≤ x ≤ 1), Li 1.1+x Ti 1.8 O4 (0 ≤ x ≤ 1), Li 1.07+x Ti 1.86 O4 (0 ≤ x ≤ 1), Li x TiO2 (0 < x ≤ 1), etc. are included. Further, the lithium titanium-containing oxide may be a lithium titanium composite oxide into which a different element has been introduced.

[0030] Examples of niobium titanium-containing oxides include TiNb2O7, Ti2Nb2O9, Ti2Nb 10 O 29 , TiNb 14 O 37 , and TiNb 24 O 62The niobium titanium-containing oxide may be a substituted niobium titanium composite oxide in which at least a part of Nb and / or Ti is substituted with a different element. Examples of the substituted element 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 may contain two or more types of substituted elements. The active material particles may contain one type of niobium titanium-containing oxide, or may contain multiple types of niobium titanium-containing oxide. The niobium titanium-containing oxide preferably contains Nb2TiO7 having a monoclinic structure. In this case, an electrode having excellent capacity and rate performance can be obtained.

[0031] Examples of monoclinic niobium titanium oxides include Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δ 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 composition formula are 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0032] Another example of a monoclinic niobium titanium oxide is Li a TiM b Nb 2±β O 7±σ (0≦a≦5, 0≦b≦0.3, 0≦β≦0.3, 0≦σ≦0.3, M is at least one element selected from the group consisting of Fe, V, Mo, and Ta).

[0033] Titanium oxide includes, for example, titanium oxide with a monoclinic structure, titanium oxide with a rutile structure, and titanium oxide with anatase structure. Titanium oxide with each crystal structure has a composition of TiO2 before charging and a composition of LiO2 after charging. xIt can be expressed as TiO2 (x is 0≦x≦1). The structure of titanium oxide with a monoclinic crystal structure before charging can be expressed as TiO2(B).

[0034] The negative electrode active material may be of one type or two or more types.

[0035] The negative electrode active material is contained in the negative electrode active material-containing portion in the form of particles, for example. The negative electrode active material particles may be primary particles, secondary particles which are aggregates of primary particles, or a mixture of a single primary particle and a secondary particle. The shape of the particles is not particularly limited, and may be, for example, spherical, elliptical, flat, or fibrous.

[0036] The average particle size (diameter) of the primary particles of the negative electrode active material is preferably 1 μm or less, more preferably 0.01 μm or more and 0.1 μm or less, and the average particle size (diameter) of the secondary particles of the negative electrode active material is preferably 10 μm or less, more preferably 1 μm or more and 5 μm or less.

[0037] <Cathode active material> When the electrode according to the embodiment is used as a positive electrode, the active material-containing portion contains a positive electrode active material. The positive electrode active material has a lithium ion absorption / release potential of 3V (vs. Li / Li) based on metallic lithium. + ) or more and 5.5V or less (vs.Li / Li + The positive electrode may contain one type of positive electrode active material, or may contain two or more types of positive electrode active materials.

[0038] 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, and phosphate compounds having an olivine crystal structure (e.g., Li x FePO4(0 <x≦1)、Li xIt contains MnPO4 (0 < x ≦ 1), etc. The phosphate compound with an olivine crystal structure is excellent in thermal stability.

[0039] 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, Li with a spinel structure x Mn2O4 (0 < x ≦ 1), Li x MnO2 (0 < x ≦ 1), etc. of lithium manganese composite oxide, for example, Li x Ni 1-y Al y O2 (0 < x ≦ 1, 0 < y < 1), etc. of lithium nickel aluminum composite oxide, for example, Li x CoO2 (0 < x ≦ 1), etc. of lithium cobalt composite oxide, for example, Li x Ni 1-y―z Co y Mn z O2 (0 < x ≦ 1, 0 < y < 1, 0 ≦ z < 1), etc. of lithium nickel cobalt composite oxide, for example, Li x Mn y Co 1-y O2 (0 < x ≦ 1, 0 < y < 1), etc. of lithium manganese cobalt composite oxide, for example, Li x Mn 1-y Ni y O4 (0 < x ≦ 1, 0 < y < 2, 0 < 1 - y < 1), etc. of spinel - type lithium manganese nickel composite oxide, for example, Li x FePO4 (0 < x ≦ 1), Li x Fe 1-y Mn y PO4 (0 < x ≦ 1, 0 ≦ y ≦ 1), Li x CoPO4 (0 < x ≦ 1), etc. of lithium phosphate oxide having an olivine structure, iron fluorosulfate (for example, Li x FeSO4F (0 < x ≦ 1)) can be mentioned.

[0040] The positive electrode active material is contained in the positive electrode active material-containing portion in the form of particles, for example. The positive electrode active material particles may be single primary particles, secondary particles which are aggregates of primary particles, or a mixture of primary particles and secondary particles. The shape of the particles is not particularly limited, and may be, for example, spherical, elliptical, flat, or fibrous.

[0041] The average particle size (diameter) of the primary particles of the positive electrode active material is preferably 1 μm or less, more preferably 0.01 μm or more and 0.1 μm or less, and the average particle size (diameter) of the secondary particles of the positive electrode active material is preferably 10 μm or less, more preferably 1 μm or more and 5 μm or less.

[0042] <Binding agent> The binder has the function of binding the active material and the current collector. The binder is blended to fill the gaps between the dispersed active material and to bind the active material and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene butadiene 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 may be used in combination as the binder.

[0043] The binder is preferably polyvinylidene fluoride, which has excellent binding properties. Styrene-butadiene rubber is also a preferable binder. Styrene-butadiene rubber is an emulsion and can be easily impregnated with electrolyte, so it can be easily soaked into the current collector.

[0044] <Conductive agent> The conductive agent is added as necessary in order to improve current collecting performance and reduce the contact resistance between the active material and the current collector.

[0045] Examples of the conductive agent include carbonaceous materials such as acetylene black, ketjen black, graphite, and coke. The conductive agent may be used alone or in combination of two or more kinds.

[0046] <Mixing ratio of active material, conductive agent and binder> The mixing ratio of the active material, conductive agent and binder in the active material-containing part can be changed as appropriate. For example, it is preferable to mix the active material, conductive agent and binder in a ratio of 68% by weight or more and 96% by weight or less, 2% by weight or more and 30% by weight or less, and 2% by weight or more and 30% by weight or less, respectively. By making the amount of the conductive agent 2% by weight or more, the current collection performance of the active material-containing part can be improved. In addition, by making the amount of the binder 2% by weight or more, the binding property between the active material-containing part and the current collector becomes sufficient, and excellent cycle performance can be expected. On the other hand, it is preferable to make the conductive agent and the binder 30% by weight or less each in order to achieve high capacity.

[0047] The electrodes of the embodiment are not limited to a sheet shape, and may be formed to have a three-dimensional structure. By using the electrodes of the embodiment for both the negative electrode and the positive electrode, it is possible to take a shape such as that shown in FIG. 3 or FIG. 4. In FIG. 3, one electrode is cylindrical with a cavity, and the other electrode is present in the cavity of the other electrode, resulting in a concentric structure. In FIG. 4, the electrodes have a comb-tooth structure, and the convex portions and concave portions of the one electrode and the other electrode are arranged relative to each other.

[0048] <Various measurement methods> The confirmation of the composition of the current collector, the measurement of the first porosity, and the measurement of the second porosity will be described below.

[0049] When the electrode of the embodiment is included in a battery, the battery is disassembled and a part of the electrode is cut out. As a method, a battery in a fully discharged state (SOC (State of Charge) 0%) is disassembled in a glove box filled with argon. A sample is cut out from the center of the removed electrode, for example, in a size of 2 cm x 2 cm. As a method of cutting out, for example, a water jet cutter can be used to cut out the desired size. By using this, even metal materials can be cut without heat of abrasion. If there are measurement constraints on the sample to be used for measurement, it is cut out to a smaller size and the measurement is performed. If the electrolyte contained in the electrode is an aqueous electrolyte, pure water is selected as the solvent to be used from here on. If it is a non-aqueous electrolyte, N-methylpyrrolidone (NMP) solvent is selected.

[0050] <Confirmation of current collector composition> When the current collector contains a metal, the elemental composition of the metal can be confirmed by inductively coupled plasma (ICP) emission spectroscopy.

[0051] The cut sample is immersed in pure water or NMP solvent and ultrasonically cleaned at 45°C for 1 hour. The sample is then removed and the same treatment is repeated twice in fresh pure water or NMP solvent. The sample is then shaken in fresh pure water or NMP solvent for 10 seconds and dried at 120°C for 3 hours. This allows a current collector to be obtained from the electrode with the deposits removed. ICP measurements are then performed on the resulting current collector.

[0052] <First porosity measurement> The first porosity can be measured by observing a cross section of the current collector with a scanning electron microscope (SEM).

[0053] The method involves obtaining a current collector in the same way as for confirming the composition of the current collector, then cutting a cross section in the thickness direction using a focused ion beam (FIB) and observing it with an SEM. Then, cross-section processing in the same direction using FIB and observation with an SEM are repeated. The FIB processing pitch is about 150 nm, and FIB processing and SEM observation are repeated 100 times. This allows for the acquisition of SEM observation images of a continuous cross section.

[0054] During SEM observation, the distribution of the current collector in the acquired SEM cross-sectional image can be quantified by mapping using energy dispersive X-ray spectroscopy (EDX). If a metal element is confirmed by the above method, the mapping image of the corresponding metal element is binarized by image analysis, and the ratio of the area of ​​the void portion (other than the current collector) to the total area of ​​the image can be calculated. If a metal element is not confirmed, the contrast difference between the current collector and the coating portion other than the current collector is increased, and image analysis is performed when the difference between the current collector and the coating portion is clear. This is performed for all SEM cross-sectional images acquired by FIB processing. By adding up all the SEM cross-sectional images and reconstructing them into a three-dimensional image, it is possible to calculate the porosity in the three-dimensional structure. This allows the first porosity to be measured.

[0055] <Second porosity measurement> The second porosity can be measured by obtaining a pore distribution by mercury intrusion porosimetry using electrodes. For example, Shimadzu Autopore 9520 can be used as a measuring device for the mercury intrusion porosimetry.

[0056] The cut sample is washed with pure water or NMP solvent. If the electrode is not washed sufficiently after removal from the battery, it may be difficult to observe the second porosity due to the influence of lithium salts (such as lithium fluoride) remaining in the electrode. The pore diameter is obtained from the pore size distribution by mercury intrusion porosimetry. The analytical principle of mercury intrusion porosimetry is based on Washburn's formula (A).

[0057] D=-4γcosθ / P (A) where P is the applied pressure, D is the pore diameter, and γ is the surface tension of mercury (480 dyne cm -1 ), is the contact angle between mercury and the pore wall surface, which is 140°. Since γ and θ are constants, the relationship between the applied pressure P and the pore diameter D can be obtained from the Washburn equation, and by measuring the volume of mercury intrusion at that time, the pore diameter and its volume distribution can be derived. The porosity of the sample can be quantified from the obtained pore diameter and the sum of the amount present.

[0058] <Manufacturing method> The electrode according to the embodiment can be manufactured, for example, as follows. First, a slurry in which a positive electrode active material or a negative electrode active material is dispersed in a solvent is prepared. A porous current collector is impregnated with this, and is left to stand under reduced pressure, and then removed. The surface is then wiped and dried. This makes it possible to manufacture an electrode in which an active material is supported on the inner surface of a porous current collector. At this time, the viscosity of the slurry is preferably 1 mPa·s or more and 10 mPa·s. If it is less than 1 mPa·s, the active material material is likely to settle in the slurry, making it difficult to obtain a uniform electrode. On the other hand, if it is 10 mPa·s or more, it becomes difficult for the slurry to penetrate into the inside of the porous current collector, and a sufficient amount of active material cannot be supported on the current collector. It is preferable to reduce the pressure during impregnation to a level that does not volatilize the solvent used in the slurry. By reducing the pressure to between -80 kPa and -50 kPa in the case of N-methylpyrrolidone (NMP), or between -60 kPa and 40 kPa in the case of a water solvent, the slurry can be impregnated into the interior of the porous current collector without excessive volatilization of the solvent.

[0059] The electrode according to the first embodiment includes a current collector and an active material-containing portion. The current collector has a first porosity of 70% or more and 90% or less. The electrode has a second porosity of 60% or more and 80% or less. The active material-containing portion is supported on the current collector. With this configuration, it is possible to provide an electrode that is excellent in charge / discharge performance and can realize a high-capacity secondary battery.

[0060] Second embodiment According to a second embodiment, a secondary battery including a negative electrode, a positive electrode, and an electrolyte is provided. The secondary battery includes an electrode according to the embodiment. At least one of the negative electrode and the positive electrode is the electrode according to the first embodiment. When one of the negative electrode or the positive electrode is the electrode according to the first embodiment, the counter electrode may have a different configuration from that of the first embodiment.

[0061] The secondary battery according to the second embodiment may further include a separator disposed between the positive electrode and the negative electrode. The negative electrode, the positive electrode, and the separator may constitute an electrode group. The electrolyte may be held in the electrode group.

[0062] Moreover, the secondary battery according to the second embodiment can further include an exterior member that houses the electrode group and the electrolyte.

[0063] Furthermore, the secondary battery according to the second embodiment may further include a negative electrode terminal electrically connected to the negative electrode and a positive electrode terminal electrically connected to the positive electrode.

[0064] The secondary battery according to the second embodiment may be, for example, a water-based lithium battery.

[0065] Furthermore, the secondary battery according to the second embodiment may be, for example, a lithium ion secondary battery. The secondary battery includes a non-aqueous electrolyte secondary battery that contains a non-aqueous electrolyte.

[0066] An example in which the battery of the embodiment is applied to a secondary battery will be described with reference to FIGS.

[0067] The secondary battery 1 includes an electrode group 1a and an exterior member 20 in which the electrode group 1a is housed. The electrode group 1a is housed in the exterior member 20, which is a rectangular cylindrical metal container. The electrode group 1a includes a negative electrode 3, a separator 4, and a positive electrode 5. The electrode group 1a has a structure in which the separator 4 is interposed between the positive electrode 5 and the negative electrode 3 and wound in a spiral shape to form a flat shape. An aqueous electrolyte (not shown) is held in the electrode group 1a. As shown in FIG. 6, a strip-shaped negative electrode lead 16 is electrically connected to each of a plurality of points on the end of the negative electrode 3 located on the end face of the electrode group 1a. In addition, a strip-shaped positive electrode lead 17 is electrically connected to each of a plurality of points on the end of the positive electrode 5 located on this end face. The plurality of negative electrode leads 16 are connected to the negative electrode terminal 6 in a bundled state as shown in FIG. 6. In addition, although not shown, the positive electrode lead 17 is also electrically connected to the positive electrode terminal 7 in a bundled state.

[0068] The metal sealing plate 21 is fixed to an opening of the metal exterior member 20 by welding or the like. The negative electrode terminal 6 and the positive electrode terminal 7 are each drawn out to the outside through an extraction hole provided in the sealing plate 21. A negative electrode gasket 8 and a positive electrode gasket 9 are disposed on the inner circumferential surface of each extraction hole of the sealing plate 21 to prevent a short circuit due to contact with the negative electrode terminal 6 and the positive electrode terminal 7, respectively. By disposing the negative electrode gasket 8 and the positive electrode gasket 9, the airtightness of the secondary battery 100 can be maintained.

[0069] A control valve 22 (safety valve) is disposed on the sealing plate 21. When the internal pressure of the battery cell increases due to gas generated in the exterior member 20, the generated gas can be released to the outside from the control valve 22. The control valve 22 may be of a reset type that operates when the internal pressure exceeds a set value and functions as a sealing plug when the internal pressure decreases. Alternatively, a non-reset type control valve that does not recover its function as a sealing plug once it is activated may be used. In FIG. 5, the control valve 22 is disposed in the center of the sealing plate 21, but the control valve 22 may be located at the end of the sealing plate 21. The control valve 22 may be omitted.

[0070] Further, the sealing plate 21 is provided with a liquid inlet 23. The electrolyte can be injected through this liquid inlet 23. After the electrolyte is injected, the liquid inlet 23 can be closed by a sealing plug 24. The liquid inlet 23 and the sealing plug 24 may be omitted.

[0071] Another example of the secondary battery will be described with reference to Figures 7 and 8. Figures 7 and 8 show an example of a secondary battery 1 that uses an exterior member made of a laminate film as a container.

[0072] The secondary battery 1 shown in Figures 7 and 8 includes an electrode group 1a shown in Figures 7 and 8, an exterior member 20 shown in Figure 7, and an electrolyte (not shown). The electrode group 1a and the electrolyte are housed in the exterior member 20. The electrolyte is held in the electrode group 1a.

[0073] The exterior member 20 is made of a laminate film including two resin layers and a metal layer interposed between them.

[0074] The electrode group 1a is a laminated electrode group, as shown in Fig. 8. The laminated electrode group 1a has a structure in which negative electrodes 3 and positive electrodes 5 are alternately laminated with separators 4 interposed therebetween.

[0075] The electrode group 1a includes a plurality of negative electrodes 3. Each of the plurality of negative electrodes 3 includes a negative electrode current collector 3a and a negative electrode active material-containing layer 3b supported on both sides (e.g., both main surfaces) of the negative electrode current collector 3a. The electrode group 1a also includes a plurality of positive electrodes 5. Each of the plurality of positive electrodes 5 includes a positive electrode current collector 5a and a positive electrode active material-containing layer 5b supported on both sides (e.g., the first and second surfaces) of the positive electrode current collector 5a.

[0076] The negative electrode current collector 3a of each negative electrode 3 includes a portion 3c on one side of which the negative electrode active material-containing layer 3b is not supported on any surface. This portion 3c serves as a negative electrode current collector tab. As shown in FIG. 8, the portion 3c serving as the negative electrode current collector tab does not overlap with the positive electrode 5. The 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 pulled out to the outside of the exterior member 20.

[0077] Although not shown, 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 serves as a positive electrode current collector tab. The positive electrode current collector tab does not overlap with the negative electrode 3, similar to the negative electrode current collector tab (portion 3c). The positive electrode current collector tab is located on the opposite side of the electrode group 1a to the negative electrode current collector tab (portion 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 to the negative electrode terminal 6 and is drawn out to the outside of the exterior member 20.

[0078] The counter electrode, the electrolyte, the separator, the exterior member, the negative electrode terminal, and the positive electrode terminal will be described in detail below.

[0079] 1) Counter electrode The counter electrode may include a current collector and an active material-containing layer. The active material-containing layer may be supported on one side or both sides of the current collector. The active material-containing layer may include an active material, a conductive agent, and a binder. The active material-containing layer may or may not include fibrous carbon. The counter electrode is a negative electrode when the electrode according to the embodiment is a positive electrode, and is a positive electrode when the electrode according to the embodiment is a negative electrode. Here, the counter electrode is described as a positive electrode.

[0080] The positive electrode current collector can be formed from a material that is electrochemically stable at a potential at which lithium (Li) is inserted into and extracted from the active material. Examples of the positive electrode current collector include a conductive sheet containing a conductive material and a polymer material, a conductive sheet containing at least one metal element selected from the group consisting of Pb, Bi, Zn, Sb, and Sn, a metal foil such as copper, nickel, stainless steel, or aluminum, and an aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. Examples of the polymer material of the conductive sheet include polyethylene, polypropylene, polyethylene terephthalate, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, and the like. As the conductive material, it is preferable to use a conductive filler such as a carbonaceous material. Examples of the carbonaceous material include carbon black, ketjen black, graphite, fibrous carbon, carbon nanotubes, and the like. The types of the conductive material and the polymer material can be one type or two or more types.

[0081] 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 material.

[0082] 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)), and the like. The phosphate compound having an olivine crystal structure has excellent thermal stability.

[0083] Examples of cathode active materials capable of obtaining a high cathode potential include lithium nickel cobalt manganese composite oxides (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), etc. lithium manganese composite oxides, for example, Li x Ni 1-y Al y O2 (0 < x ≤ 1, 0 < y < 1), etc. lithium nickel aluminum composite oxides, for example, Li x CoO2 (0 < x ≤ 1), etc. 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), etc. lithium nickel cobalt composite oxides, for example, Li x Mn y Co 1-y O2 (0 < x ≤ 1, 0 < y < 1), etc. lithium manganese cobalt composite oxides, for example, Li x Mn 1-y Ni y O4 (0 < x ≤ 1, 0 < y < 2, 0 < 1 - y < 1), etc. spinel-type lithium manganese nickel composite oxides, for example, Li x FePO4 (0 < x ≤ 1), Li x Fe 1-y Mn y PO4 (0 < x ≤ 1, 0 ≤ y ≤ 1), Li x CoPO4 (0 < x ≤ 1), etc. lithium phosphate oxides having an olivine structure, fluorinated iron sulfate (for example, Li x FeSO4F (0 < x ≤ 1)) can be mentioned.

[0084] The cathode active material is contained in the cathode, for example, in the form of particles. The cathode 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, etc.

[0085] The average particle size (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, and the average particle size (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.

[0086] The positive electrode active material-containing layer may contain a binder. The binder has the function of binding the active material and the current collector. The binder is blended to fill the gaps between the dispersed active material and to bind the active material and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, styrene butadiene 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 may be used in combination as the binder.

[0087] The positive electrode active material-containing layer may contain, in addition to the positive electrode active material and the binder, a conductive agent, etc. The conductive agent is mixed as necessary in order to improve current collection performance and reduce contact resistance between the active material and the current collector.

[0088] Examples of the conductive agent include carbonaceous materials such as acetylene black, ketjen black, graphite, and coke. The conductive agent may be used alone or in combination of two or more kinds.

[0089] In the positive electrode active material-containing layer, the positive electrode active material and the binder are preferably mixed in an amount of 80% by weight to 98% by weight and 2% by weight to 20% by weight, respectively.

[0090] By making the amount of binder 2% by weight or more, sufficient electrode strength can be obtained. In addition, the binder can function as an insulator. Therefore, by making the amount of binder 20% by weight or less, the amount of insulator contained in the electrode is reduced, and the internal resistance can be reduced.

[0091] When a conductive agent is added, the positive electrode active material, binder, and conductive agent are preferably mixed in proportions of 77% by weight to 95% by weight, 2% by weight to 20% by weight, and 3% by weight to 15% by weight, respectively.

[0092] By making the amount of the conductive agent 3% by weight or more, the above-mentioned effects can be achieved. Also, by making the amount of the conductive agent 15% by weight or less, the ratio of the conductive agent in contact with the electrolyte can be reduced. If this ratio is low, decomposition of the electrolyte during high-temperature storage can be reduced.

[0093] 2) Electrolyte The electrolyte of the secondary battery according to the embodiment may be an electrolyte containing water or a non-aqueous electrolyte. The electrolyte may have a high viscosity, and may be 200 mPa·s or more, but is preferably 10000 mPa·s or less. When the electrolyte has a viscosity in a desired range, the second porosity is 60% or more and 80% or less, so that the electrolyte can be impregnated into the inside of the electrode.

[0094] Here, the electrolyte will be described as an electrolyte containing water. Hereinafter, an electrolyte containing water may be referred to as an aqueous electrolyte.

[0095] The aqueous electrolyte includes an aqueous solvent and an electrolyte salt dissolved in the aqueous solvent. The aqueous electrolyte may be liquid or gel. The liquid aqueous electrolyte is, for example, an aqueous solution prepared by dissolving an electrolyte salt as a solute in an aqueous solvent. The gel aqueous electrolyte is, for example, prepared by mixing a liquid aqueous electrolyte with a polymer compound to form a composite. Examples of the polymer compound include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), and polyethylene oxide (PEO). When the aqueous electrolyte is held in both the negative electrode active material-containing layer and the positive electrode active material-containing layer, the types of the aqueous electrolytes may be the same or different.

[0096] The aqueous solution preferably contains 1 mol or more of the aqueous solvent per mol of the salt as the solute, and more preferably 3.5 mol or more.

[0097] As the aqueous solvent, a solution containing water can be used. The aqueous solution may be pure water or a mixed solvent of water and an organic solvent. The aqueous solvent contains water at a ratio of, for example, 50% by volume or more.

[0098] The electrolyte salt may be, for example, a lithium salt, a sodium salt, or a mixture thereof. One or more kinds of electrolyte salts may be used.

[0099] Examples of the lithium salt 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 difluorooxalatoborate (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 bisoxalatoborate (LiBOB: LiB[(OCO)2]2).

[0100] 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 room temperature, but can be changed to a liquid state by a eutectic reaction with a compound containing an amide bond. Therefore, it can contribute to reducing the water content in the aqueous electrolyte. LiTFSI; LiN(CF3SO2)2) is preferable.

[0101] As the sodium salt, sodium chloride (NaCl), sodium sulfate (Na2SO4), sodium hydroxide (NaOH), sodium nitrate (NaNO3), sodium trifluoromethanesulfonylamide (NaTFSA), and the like can be used.

[0102] Aqueous electrolytes contain chloride ions (Cl - ), hydroxide ion (OH - ), sulfate ion (SO4 2- ), nitrate ion (NO3 - It is preferable that the composition contains at least one selected from the following:

[0103] The aqueous electrolyte may contain a compound containing an amide bond. This can suppress the electrolysis of water, thereby improving the charge / discharge performance. The compound containing an amide bond can form a liquid mixture by 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 a desired lithium ion concentration even with a small amount of aqueous solvent. Therefore, it is possible to suppress the electrolysis of water without impairing the ionic conductivity of the aqueous electrolyte.

[0104] Examples of the compound containing an amide bond include those described for the negative electrode. The type of compound containing an amide bond may be one type or two or more types.

[0105] The content of the compound containing an amide bond in the aqueous electrolyte can be 30% by weight or more and 55% by weight or less. A more preferred range is 30% by weight or more and 45% by weight or less. By setting the content in the above range, a nitrogen-containing compound coating can be formed on the surface of the negative electrode active material particles. In addition, even if the amount of the aqueous solvent in the aqueous electrolyte is small, the lithium salt can be present in a liquid state.

[0106] The aqueous electrolyte may contain potassium hydroxide (KOH). Potassium hydroxide can function as a catalyst for the reaction of forming a coating on the surface of the negative electrode active material particles. Therefore, when the aqueous electrolyte contains a compound containing an amide bond and potassium hydroxide, it is possible to promote the formation of a nitrogen-containing compound coating on the surface of the negative electrode active material particles.

[0107] The pH of the aqueous electrolyte is preferably 3 or more and 14 or less, and more preferably 4 or more and 13 or less. When separate electrolytes are used for the negative electrode side electrolyte and the positive electrode side electrolyte, the pH of the negative electrode side electrolyte is preferably in the range of 3 or more and 14 or less, and the pH of the positive electrode side electrolyte is preferably in the range of 1 or more and 8 or less.

[0108] When the pH of the negative electrode electrolyte is within the above range, the hydrogen generation potential at the negative electrode is reduced, and hydrogen generation at the negative electrode is suppressed. This improves the storage performance and cycle life performance of the battery. When the pH of the positive electrode electrolyte is within the above range, the oxygen generation potential at the positive electrode is increased, and oxygen generation at the positive electrode is reduced. This improves the storage performance and cycle life performance of the battery. It is more preferable that the pH of the positive electrode electrolyte is within the range of 3 to 7.5.

[0109] The aqueous electrolyte may contain a surfactant. Examples of the surfactant include nonionic surfactants such as polyoxyalkylene alkyl ether, polyethylene glycol, polyvinyl alcohol, thiourea, disodium 3,3'-dithiobis(1-propanephosphoric acid), dimercaptothiadiazole, boric acid, oxalic acid, malonic acid, saccharin, sodium naphthalenesulfonate, gelatin, potassium nitrate, aromatic aldehyde, and heterocyclic aldehyde. The surfactant may be used alone or in combination of two or more.

[0110] 3) Separator The separator is disposed, for example, between the positive electrode and the negative electrode. The separator may include a separator that covers only one of the positive electrode or the negative electrode.

[0111] The separator can have a porous structure. Examples of the porous separator include nonwoven fabric, film, and paper. Examples of the constituent materials of the porous separator that constitutes the nonwoven fabric, film, and paper include polyolefins such as polyethylene and polypropylene, and cellulose. Examples of preferred porous separators include nonwoven fabrics containing cellulose fibers and porous films containing polyolefin fibers.

[0112] The porosity of the porous separator is preferably 60% or more. The fiber diameter is preferably 10 μm or less. By making the fiber diameter 10 μm or less, the affinity of the porous separator to the electrolyte is improved, so that the battery resistance can be reduced. The fiber diameter is more preferably in the range of 3 μm or less. A cellulose fiber-containing nonwoven fabric with a porosity of 60% or more has good electrolyte impregnation and can provide high output performance from low to high temperatures. The porosity is more preferably in the range of 62% to 80%.

[0113] The porous separator has a thickness of 20 μm to 100 μm and a density of 0.2 g / cm 3 More than 0.9g / cm 3 Within this range, a balance between mechanical strength and reduced battery resistance can be achieved, and a secondary battery with high output and suppressed internal short circuit can be provided. In addition, the separator undergoes little thermal shrinkage in a high-temperature environment, and good high-temperature storage performance can be achieved.

[0114] The separator may be a composite separator including 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.

[0115] A solid electrolyte layer may be used as the separator. The solid electrolyte layer may include solid electrolyte particles and a polymer component. The solid electrolyte layer may be composed of only solid electrolyte particles. The solid electrolyte layer may include one type of solid electrolyte particles, or may include multiple types of solid electrolyte particles. The solid electrolyte layer may include at least one selected from the group consisting of a plasticizer and an electrolyte salt. When the solid electrolyte layer includes an electrolyte salt, for example, the alkali metal ion conductivity of the solid electrolyte layer can be further increased. The form of the polymer material may be, for example, granular or fibrous.

[0116] The solid electrolyte layer is preferably in a sheet shape 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.

[0117] The polymer component used in the solid electrolyte layer is preferably a polymer component insoluble in an aqueous solvent. 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. In addition, inorganic solid electrolytes have high stability against water and excellent lithium ion conductivity. By forming a composite of a lithium ion conductive inorganic solid electrolyte and a fluorine-containing polymer component, a flexible solid electrolyte layer with alkali metal ion conductivity can be realized. A separator made of this solid electrolyte layer can reduce resistance, thereby improving the large current performance of a secondary battery.

[0118] Examples of the fluorine-containing polymer component include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride (PVdF), etc. The type of the fluorine-containing polymer component can be one or more types.

[0119] When the solid electrolyte layer contains a polymer component, the content of the polymer component in the solid electrolyte layer is preferably 1% by weight or more and 20% by weight or less. In this range, when the thickness of the solid electrolyte layer is set in the range of 10 to 100 μm, high mechanical strength can be obtained and resistance can be reduced. Furthermore, there is little risk that the solid electrolyte will become a factor that inhibits lithium ion conductivity. A more preferable range of this content is 3% by weight or more and 10% by weight or less.

[0120] As the solid electrolyte, it is preferable to use an inorganic solid electrolyte. The inorganic solid electrolyte is a solid substance having Li-ion conductivity. Here, having Li-ion conductivity is 1×10 -6 It means that the inorganic solid electrolyte has a lithium ion conductivity of 1.0 S / cm or more. Examples of the inorganic solid electrolyte include oxide-based solid electrolytes and sulfide-based solid electrolytes. Specific examples of the inorganic solid electrolyte are as follows.

[0121] The oxide-based solid electrolyte has a NASICON (Sodium (Na) Super Ionic Conductor) type structure and is represented by the general formula Li 1+x It is preferable to use a lithium phosphate solid electrolyte represented by 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.

[0122] A specific example of a lithium phosphate solid electrolyte having a NASICON structure is Li 1+x Al x Ti 2-x LATP compound represented by (PO4)3, where 0.1≦x≦0.5; Li 1+x Al y Mβ 2-y A compound represented by the formula (PO4)3, in which 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; Li 1+x Al x Ge 2-x (PO4)3, where 0≦x≦2; and Li 1+x Al x Zr 2-x (PO4)3, where 0≦x≦2; Li 1+x+y Al x Mγ 2-x S y P 3-y O 12A compound represented by [compound formula] where Mγ is one or more selected from the group consisting of Ti and Ge, 0 < x ≦ 2, and 0 ≦ y < 3; Li 1+2x Zr 1-x Ca x Compounds represented by [compound formula] where 0 ≦ x < 1 can be mentioned.

[0123] In addition to the above lithium phosphate solid electrolyte, as the oxide-based solid electrolyte, there are also Li x PO y N z Amorphous LIPON compounds represented by [compound formula] where 2.6 ≦ x ≦ 3.5, 1.9 ≦ y ≦ 3.8, and 0.1 ≦ z ≦ 1.3 (for example, Li 2.9 PO 3.3 N 0.46 ); Garnet-type structure La 5+x A x La 3-x Mδ2O 12 Compounds represented by [compound formula] where A is one or more selected from the group consisting of Ca, Sr, and Ba, Mδ is one or more selected from the group consisting of Nb and Ta, and 0 ≦ x ≦ 0.5; Li3Mδ 2-x L2O 12 Compounds represented by [compound formula] where Mδ is one or more selected from the group consisting of Nb and Ta, L may contain Zr, and 0 ≦ x ≦ 0.5; Li 7-3x Al x La3Zr3O 12 Compounds represented by [compound formula] where 0 ≦ x ≦ 0.5; Li 5+x La3Mδ 2-x Zr x O 12 LLZ compounds represented by [compound formula] where Mδ is one or more selected from the group consisting of Nb and Ta and 0 ≦ x ≦ 2 (for example, Li7La3Zr2O 12 ); And compounds represented by La 2 / 3-x Li x TiO3 having a perovskite-type structure where 0.3 ≦ x ≦ 0.7 can be mentioned.

[0124] One or more of the above compounds can be used as the solid electrolyte. It is also possible to use two or more of the above solid electrolytes.

[0125] 4) Exterior member The exterior member contains at least a positive electrode, a negative electrode, a separator, and an aqueous electrolyte. For example, a metal container, a laminated film container, or a resin container can be used as the exterior member. For the metal container, a metal can made of nickel, iron, stainless steel, or the like, having a rectangular or cylindrical shape can be used. For the resin container, a container made of polyethylene, polypropylene, or the like can be used.

[0126] The thickness of the laminate film is, for example, 0.5 mm or less, preferably 0.2 mm or less.

[0127] The laminate film is a multi-layer film including a plurality of resin layers and a metal layer interposed between the resin layers. The resin layers include polymeric 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 the exterior member by sealing it by heat fusion.

[0128] The thickness of the wall of the metal container is, for example, 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.2 mm or less.

[0129] The metal container is made of, for example, aluminum or an aluminum alloy. The aluminum alloy preferably contains elements such as magnesium, zinc, and silicon. When the aluminum alloy contains transition metals such as iron, copper, nickel, and chromium, the content of the transition metals is preferably 100 ppm by weight or less.

[0130] The shape of the exterior member is not particularly limited. The shape of the exterior member may be, for example, flat (thin), rectangular, cylindrical, coin, or button. The exterior member can be appropriately selected depending on the battery dimensions and the application of the battery.

[0131] The secondary battery according to the embodiment can be used in various forms such as a square, cylindrical, flat, thin, coin type, etc. The secondary battery may 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 single current collector and a negative electrode active material-containing layer is provided on the other side. In this case, there is an advantage that a plurality of cells connected in series can be produced from a single cell.

[0132] 5) Negative terminal The negative electrode terminal can be formed from a material that is electrochemically stable at the Li absorption / release potential of the above-mentioned negative electrode active material and has electrical conductivity. Specifically, the material of the negative electrode terminal can be copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. The material of the negative electrode terminal is preferably aluminum or an aluminum alloy. The negative electrode terminal is preferably made of the same material as the negative electrode current collector in order to reduce the contact resistance with the negative electrode current collector.

[0133] 6) Positive terminal The positive electrode terminal can be formed from a material that is electrically stable in a potential range of 3 V to 4.5 V (vs. Li / Li+) relative to the redox potential of lithium and has electrical conductivity. Examples of the material for the positive electrode terminal include aluminum and aluminum alloys containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. The positive electrode terminal is preferably formed from the same material as the positive electrode current collector in order to reduce the contact resistance with the positive electrode current collector.

[0134] The secondary battery according to the embodiment includes the electrode according to the embodiment, and therefore the secondary battery can have excellent life performance.

[0135] (Third embodiment) According to a third embodiment, there is provided a battery pack including a plurality of secondary batteries according to the embodiment.

[0136] In the battery pack according to this embodiment, the individual cells may be electrically connected in series or in parallel, or may be connected in a combination of series and parallel.

[0137] Next, an example of a battery pack will be described with reference to the drawings.

[0138] 9 includes five cells 100a to 100e, four bus bars 201, a positive electrode lead 207, and a negative electrode lead 206. Each of the five cells 100a to 100e is a secondary battery according to the embodiment.

[0139] The bus bar 201 connects, for example, the negative electrode terminal 6 of one cell 100a and the positive electrode terminal 7 of the adjacent cell 100b. In this way, the five cells 100 are connected in series by the four bus bars 201. That is, the battery pack 200 in FIG. 7 is a five-series battery pack. Although no example is shown, in a battery pack including a plurality of cells electrically connected in parallel, for example, the plurality of negative electrode terminals are connected to each other by a bus bar and the plurality of positive electrode terminals are connected to each other by a bus bar, so that the plurality of cells are electrically connected to each other.

[0140] The positive electrode terminal 7 of at least one of the five cells 100a to 100e is electrically connected to a positive electrode lead 207 for external connection. In addition, the negative electrode terminal 6 of at least one of the five cells 100a to 100e is electrically connected to a negative electrode lead 206 for external connection.

[0141] The battery pack according to the embodiment includes the electrodes according to the embodiment, and therefore the battery pack has excellent charge / discharge performance and can achieve a high capacity.

[0142] (Fourth embodiment) According to a fourth embodiment, a battery pack including a secondary battery according to the embodiment is provided. The battery pack may include the battery assembly according to the embodiment. The battery pack may include a single battery instead of the battery assembly according to the embodiment.

[0143] Such a battery pack may further include a protection circuit. The protection circuit has a function of controlling charging and discharging of the secondary battery. Alternatively, a circuit included in a device (e.g., electronic device, automobile, etc.) that uses the battery pack as a power source may be used as the protection circuit for the battery pack.

[0144] The battery pack may further include an external terminal for current flow. The external terminal for current flow is for outputting current from the secondary battery to the outside and / or inputting current from the 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 terminal for current flow. When the battery pack is charged, a charging current (including regenerative energy from the power of an automobile or the like) is supplied to the battery pack through the external terminal for current flow.

[0145] Next, an example of a battery pack according to an embodiment will be described with reference to the drawings.

[0146] The battery pack 300 shown in Figs. 10 and 11 includes a container 31, a lid 32, a protective sheet 33, a battery pack 200, a printed wiring board 34, wiring 35, and an insulating plate (not shown).

[0147] 10 is a bottomed, square container having a rectangular bottom. The container 31 is configured to be able to accommodate a protective sheet 33, a battery pack 200, a printed wiring board 34, and wiring 35. The lid 32 has a rectangular shape. The lid 32 covers the container 31 to accommodate the battery pack 200 and the like. Although not shown, the container 31 and the lid 32 are provided with openings or connection terminals for connection to an external device or the like.

[0148] The battery pack 200 includes a plurality of cells 100, a positive electrode lead 207, a negative electrode lead 206, and an adhesive tape .

[0149] At least one of the plurality of unit cells 100 is a secondary battery according to the embodiment. Each of the plurality of unit cells 100 is electrically connected in series as shown in FIG. 11. The plurality of unit cells 100 may be electrically connected in parallel, or may be connected in a combination of series and parallel connections. When the plurality of unit cells 100 are connected in parallel, the battery capacity is increased compared to when they are connected in series.

[0150] The adhesive tape 36 fastens the plurality of unit cells 100. The plurality of unit cells 100 may be fixed using heat shrink tape instead of the adhesive tape 36. In this case, the protective sheets 33 are disposed on both side surfaces of the battery pack 200, the heat shrink tape is wrapped around the battery pack 200, and the heat shrink tape is then thermally shrunk to bind the plurality of unit cells 100 together.

[0151] One end of the positive electrode lead 207 is connected to the battery pack 200. One end of the positive electrode lead 207 is electrically connected to the positive electrode of one or more of the cells 100. One end of the negative electrode lead 206 is connected to the battery pack 200. One end of the negative electrode lead 206 is electrically connected to the negative electrode of one or more of the cells 100.

[0152] The printed wiring board 34 is disposed along one of the short side surfaces of the inner surface of the container 31. The printed wiring board 34 includes a positive connector 342, a negative connector 343, a thermistor 345, a protection circuit 346, wiring 342a and 343a, an external terminal 350 for supplying electricity, a positive wiring (positive wiring) 348a, and a negative wiring (negative wiring) 348b. One main surface of the printed wiring board 34 faces one side of the battery pack 200. An insulating plate (not shown) is interposed between the printed wiring board 34 and the battery pack 200.

[0153] The other end 207a of the positive electrode lead 207 is electrically connected to the positive electrode connector 342. The other end 206a of the negative electrode lead 206 is electrically connected to the negative electrode connector 343.

[0154] The thermistor 345 is fixed to one main surface of the printed wiring board 34. The thermistor 345 detects the temperature of each of the cells 100, and transmits a detection signal to the protection circuit 346.

[0155] The external terminal 350 for current supply is fixed to the other main surface of the printed wiring board 34. The external terminal 350 for current supply is electrically connected to a device present outside the battery pack 300. The external terminal 350 for current supply includes a positive terminal 352 and a negative terminal 353.

[0156] The protection circuit 346 is fixed to the other main surface of the printed wiring board 34. The protection circuit 346 is connected to the positive terminal 352 via a positive wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via a negative wiring 348b. The protection circuit 346 is also electrically connected to the positive electrode connector 342 via a wiring 342a. The protection circuit 346 is electrically connected to the negative electrode connector 343 via a wiring 343a. Furthermore, the protection circuit 346 is electrically connected to each of the plurality of single cells 100 via the wiring 35.

[0157] The protective sheet 33 is disposed on both inner surfaces in the long side direction of the container 31 and on the inner surface in the short side direction that faces the printed wiring board 34 via the battery pack 200. The protective sheet 33 is made of, for example, resin or rubber.

[0158] The protection circuit 346 controls charging and discharging of the multiple cells 100. In addition, the protection circuit 346 cuts off electrical connection between the protection circuit 346 and external terminals 350 (positive terminal 352, negative terminal 353) for supplying electricity to an external device, based on a detection signal transmitted from the thermistor 345, or a detection signal transmitted from each of the cells 100 or the battery pack 200.

[0159] An example of the detection signal transmitted from the thermistor 345 is a signal that detects that the temperature of the cell 100 is equal to or higher than a predetermined temperature. An example of the detection signal transmitted from each cell 100 or the battery pack 200 is a signal that detects overcharging, overdischarging, and overcurrent of the cell 100. When detecting overcharging or the like for each cell 100, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each cell 100.

[0160] The protection circuit 346 may be a circuit included in a device (such as an electronic device or an automobile) that uses the battery pack 300 as a power source.

[0161] As described above, the battery pack 300 includes the external terminal 350 for current supply. Therefore, the battery pack 300 can output a current from the assembled battery 200 to an external device and input a current from the external device to the assembled battery 200 via the external terminal 350 for current supply. In other words, when the battery pack 300 is used as a power source, the current from the assembled battery 200 is supplied to the external device through the external terminal 350 for current supply. When the battery pack 300 is charged, a charging current from the external device is supplied to the battery pack 300 through the external terminal 350 for current supply. When the battery pack 300 is used as an in-vehicle battery, regenerative energy of the vehicle's power can be used as the charging current from the external device.

[0162] The battery pack 300 may include a plurality of assembled batteries 200. In this case, the assembled batteries 200 may be connected in series, in parallel, or in a combination of series and parallel connections. The printed wiring board 34 and the wiring 35 may be omitted. In this case, the positive electrode lead 207 and the negative electrode lead 206 may be used as the positive and negative terminals of the external terminals for current supply, respectively.

[0163] Such a battery pack is used in applications that require excellent cycle performance, for example, when a large current is drawn. Specifically, the battery pack is used, for example, as a power source for electronic devices, a stationary battery, or an on-board battery for various vehicles. An example of the electronic device is a digital camera. The battery pack is particularly suitable for use as an on-board battery.

[0164] The battery pack according to the fourth embodiment includes the electrode according to the embodiment or the battery according to the embodiment, and therefore the battery pack has excellent charge / discharge performance and can achieve a high capacity.

[0165] Fifth embodiment According to a fifth embodiment, a vehicle including a battery pack according to an embodiment is provided.

[0166] In such a vehicle, the battery pack, for example, recovers regenerative energy of the vehicle's motive power. The vehicle may include a mechanism (regenerator) that converts the kinetic energy of the vehicle into regenerative energy.

[0167] Examples of vehicles according to the embodiment include two-wheeled to four-wheeled hybrid electric vehicles, two-wheeled to four-wheeled electric vehicles, power-assisted bicycles, and rail vehicles.

[0168] The mounting position 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, the battery pack can be mounted in the engine compartment, the rear of the vehicle body, or under the seat of the vehicle.

[0169] The vehicle according to the embodiment may be equipped with a plurality of battery packs. In this case, the batteries included in each battery pack may be electrically connected in series, electrically connected in parallel, or electrically connected by a combination of series and parallel connections. For example, when each battery pack includes a battery pack, the battery packs may be electrically connected in series, electrically connected in parallel, or electrically connected by a combination of series and parallel connections. Alternatively, when each battery pack includes a single battery, the batteries may be electrically connected in series, electrically connected in parallel, or electrically connected by a combination of series and parallel connections.

[0170] Next, an example of a vehicle according to an embodiment will be described with reference to the drawings.

[0171] A vehicle 400 shown in Fig. 12 includes a vehicle body 40 and a battery pack 300 according to an embodiment. In the example shown in Fig. 12, the vehicle 400 is a four-wheeled automobile.

[0172] The vehicle 400 may be equipped with a plurality of battery packs 300. In this case, the batteries (e.g., single cells or assembled batteries) included in the battery pack 300 may be connected in series, in parallel, or in a combination of series and parallel connections.

[0173] 12 illustrates an example in which the battery pack 300 is mounted in an engine room located in the front of the vehicle body 40. As described above, the battery pack 300 may be mounted, for example, in the rear of the vehicle body 40 or under a seat. 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 for the motive power of the vehicle 400.

[0174] The vehicle according to the fifth embodiment is equipped with the battery pack according to the embodiment, and therefore the vehicle has excellent charge / discharge performance and can achieve high capacity.

[0175] Sixth embodiment According to a sixth embodiment, there is provided a stationary power source including a battery pack according to an embodiment.

[0176] The stationary power source may include the assembled battery according to the embodiment or the secondary battery according to the embodiment instead of the battery pack according to the embodiment. Such a stationary power source has excellent charge / discharge performance and can achieve a high capacity.

[0177] FIG. 13 is a diagram showing an application example to stationary power sources 112 and 123 as an example of use of the battery packs 300A and 300B according to the embodiment. In the example shown in FIG. 13, a system 110 in which the stationary power sources 112 and 123 are used is shown. The system 110 includes a power plant 111, a stationary power source 112, a consumer-side power system 113, and an energy management system (EMS) 115. A power grid 116 and a communication network 117 are also formed in the system 110, and the power plant 111, the stationary power source 112, the consumer-side power system 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.

[0178] The power plant 111 generates a large amount of power using fuel sources such as thermal power and atomic power. Power is supplied from the power plant 111 through a power grid 116 or the like. A battery pack 300A is mounted on the stationary power source 112. The battery pack 300A can store the power supplied from the power plant 111. The stationary power source 112 can supply the power stored in the battery pack 300A through the power grid 116 or the like. The system 110 is provided with a power conversion device 118. The power conversion device 118 includes a converter, an inverter, a transformer, and the like. Thus, the power conversion device 118 can perform conversion between direct current and alternating current, conversion between alternating currents having different frequencies, and voltage transformation (boosting and bucking), and the like. Thus, the power conversion device 118 can convert the power from the power plant 111 into power that can be stored in the battery pack 300A.

[0179] The consumer-side power system 113 includes a power system for a factory, a power system for a building, a power system for a home, etc. The consumer-side power system 113 includes a consumer-side EMS 121, a power conversion device 122, and a stationary power source 123. The stationary power source 123 is equipped with a battery pack 300B. The consumer-side EMS 121 performs control to stabilize the consumer-side power system 113.

[0180] The consumer-side power system 113 is supplied with power from the power plant 111 and power from the battery pack 300A through the power grid 116. The battery pack 300B can store the power supplied to the consumer-side power system 113. Similarly to the power conversion device 118, the power conversion device 122 includes a converter, an inverter, a transformer, and the like. Therefore, the power conversion device 122 can perform conversion between DC and AC, conversion between ACs with different frequencies, and voltage transformation (boost and step-down), etc. Therefore, the power conversion device 122 can convert the power supplied to the consumer-side power system 113 into power that can be stored in the battery pack 300B.

[0181] The power stored in the battery pack 300B can be used, for example, to charge a vehicle such as an electric car. The system 110 may also be provided with a natural energy source. In this case, the natural energy source generates power using natural energy such as wind power and solar power. Power is supplied from the natural energy source in addition to the power plant 111 through the power grid 116.

[0182] <Example> The above embodiment will be specifically described below using examples, but the present invention is not limited to the following examples as long as they do not deviate from the gist of the present invention.

[0183] Example 1 The electrodes were prepared as follows.

[0184] <Preparation of current collector> Titanium fibers with a fiber diameter of 100 μm were sintered by holding them in an Ar atmosphere at 1600°C for 5 hours, and then shaped by grinding and cutting to obtain a titanium porous plate with a thickness of 1 mm and a size of 2 cm square.

[0185] <Preparation of negative electrode> First, 100 parts by weight of the active material Li4Ti5O 12A slurry with a solid content of 40% was prepared by dispersing 10 parts by weight of conductive agent acetylene black and 5 parts by weight of binder polyvinylidene fluoride (PVdF) in N-methylpyrrolidone (NMP) solvent. The above-mentioned titanium porous plate was impregnated with the prepared slurry and allowed to stand at -60 kPa for 5 minutes. The plate was taken out, the surface was wiped, and the plate was allowed to stand in a thermostatic chamber at 120°C for 1 hour and dried. The weight of the negative electrode mixture layer supported was measured, and the plate was appropriately repeatedly impregnated with the slurry and dried until the electrode had a basis weight of 300 g / m 2 Then, one side was polished to expose the titanium metal to prepare a negative electrode.

[0186] <Preparation of positive electrode> First, 100 parts by weight of the active material LiMn2O4, 10 parts by weight of the conductive agent acetylene black, and 5 parts by weight of the binder polyvinylidene fluoride (PVdF) were dispersed in an N-methylpyrrolidone (NMP) solvent to prepare a slurry with a solid content of 40%. The above-mentioned titanium porous plate was impregnated with the prepared slurry and allowed to stand at -60 kPa for 5 minutes. It was then removed, the surface was wiped, and it was allowed to stand in a thermostatic chamber at 120°C for 1 hour to dry. One side was then polished to expose the titanium metal, and a positive electrode was prepared. The impregnation and drying of the slurry was appropriately repeated until the electrode had a basis weight of 600 g / m 2 Then, one side was polished to expose the titanium metal to prepare a positive electrode.

[0187] <Preparation of electrolyte> An aqueous solution of LiN(CF3SO2)2(LiTFSI) with a concentration of 20 mol / L was prepared and used as the electrolyte.

[0188] <Assembling secondary batteries> A glass filter was sandwiched between the negative and positive electrodes as a separator, and both sides were sandwiched between titanium plates as terminals, and fixed and pressed from the outside with polypropylene plates to prepare an electrode group. The exposed titanium metal surface of the electrode was brought into contact with the titanium plate to ensure conductivity. The electrode group was then placed in a beaker, 20 mL of electrolyte was poured in, and the electrode group was impregnated with the electrolyte by holding it at -80 kPa for 10 minutes.

[0189] <Battery evaluation: First and second porosity measurements> The battery was evaluated by repeatedly charging and discharging five times at 2.7-1.5 V and a current value of 100 mA (equivalent to a 1C rate). After the fifth cycle, the charge-discharge efficiency and the capacity per unit weight of the negative electrode active material were measured.

[0190] The first porosity was measured by cutting a cross section in the thickness direction from the obtained titanium porous plate using a focused ion beam (FIB) and observing it with a scanning electron microscope (SEM). Cross section processing in the same direction with FIB and observation with SEM were repeated 100 times. The FIB processing pitch was about 150 nm. Energy dispersive X-ray spectroscopy (EDX) was used during SEM observation, and the mapping image of the titanium element was binarized by image analysis, and the ratio of the area of ​​the void part (other than the current collector) to the total area of ​​the image was calculated.

[0191] The second porosity was measured by cutting a 2 cm square from the prepared electrode and obtaining the pore distribution by mercury intrusion porosimetry.

[0192] The first and second porosities did not change even when the battery was disassembled after the battery evaluation and then measured.

[0193] <Example 2> The same procedure was followed as in Example 1, except that titanium fibers with a fiber diameter of 50 μm were used.

[0194] <Example 3> The same procedure was followed as in Example 1, except that titanium fibers with a fiber diameter of 10 μm were used.

[0195] <Example 4> A nonwoven fabric was produced using titanium fibers with a fiber diameter of 10 μm without sintering. The produced nonwoven fabric was cut into 2 cm squares, uniaxially pressed at 30 kN, and then reshaped into 2 cm squares to obtain a current collector with a thickness of 1 mm. The production method of the current collector was the same as in Example 1.

[0196] <Example 5> The same procedure was followed as in Example 1, except that aluminum was used as the current collector metal.

[0197] <Comparative Example 1> The procedure was the same as in Example 1, except that a titanium foil having a thickness of 20 μm was used as a current collector, and the electrode was prepared by applying the slurry to the surface of the current collector.

[0198] <Comparative Example 2> The procedure was the same as in Example 1, except that an aluminum foil with a thickness of 20 μm was used as a current collector, and the electrode was prepared by applying the slurry to the surface of the current collector.

[0199] <Comparative Example 3> The procedure was the same as in Example 1, except that a titanium mesh having an opening of 200 μm was used as a current collector, and the electrode was prepared by applying the slurry to the surface of the current collector.

[0200] The results obtained in Examples 1-5 and Comparative Examples 1-3 are shown in Table 1.

[0201] [Table 1]

[0202] As is clear from Table 1, the batteries of Examples 1-5, which include a current collector with a first porosity of 70% or more and 90% or less and an electrode with a second porosity of 60% or more and 80% or less including the current collector and the active material-containing portion, exhibited high charge / discharge efficiency and also had a large capacity per unit weight of the negative electrode. The reason for this is that by satisfying the first porosity range, the specific surface area of ​​the current collector can be increased while maintaining the current collecting performance, and the amount of active material that can be supported increases. Furthermore, it is believed that by satisfying the second porosity range, the electrolyte is impregnated into the inside of the electrode, and the reactivity with the active material supported on the current collector is enhanced.

[0203] According to one or more of the embodiments and examples described above, an electrode is provided. The electrode includes a current collector and an active material-containing portion. The first porosity of the current collector is 70% or more and 90% or less, and the second porosity of the electrode is 60% or more and 80% or less. The electrode according to the embodiment can provide a high-capacity secondary battery and battery pack with excellent charge / discharge performance, as well as a vehicle and a stationary power source equipped with the battery pack.

[0204] 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, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0205] The following describes the embodiments of the invention.

[0206] <1> A first current collector having a porosity of 70% or more and 90% or less; an electrode comprising the current collector and an active material-containing portion, the electrode having a second porosity of 60% or more and 80% or less.

[0207] <2> The active material-containing portion is supported on the current collector. <1> The electrode according to claim 1.

[0208] <3> The current collector includes metal fibers. <1> or <2> The electrode according to claim 1.

[0209] <4> The fiber diameter of the metal fiber is 1 μm or more and 100 μm or less. <1> from <3> 13. The electrode according to any one of claims 1 to 12.

[0210] <5> The thickness of the current collector is 1 mm or more and 50 mm or less. <1> from <4> 13. The electrode according to any one of claims 1 to 12.

[0211] <6> A positive electrode and A negative electrode; An electrolyte; At least one of the positive electrode and the negative electrode is <1> from <5> 2. A secondary battery comprising the electrode according to claim 1.

[0212] <7> <6> A battery pack comprising the secondary battery according to claim 1.

[0213] <8> An external terminal for supplying electricity; A protection circuit; Further comprising: <7> The battery pack according to claim 1 .

[0214] <9> A battery comprising a plurality of the secondary batteries, The secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel. <7> or <8> The battery pack according to claim 1 .

[0215] <10> <7> from <9> A vehicle comprising the battery pack according to any one of claims 1 to 5.

[0216] <11> A mechanism for converting the kinetic energy of the vehicle into regenerative energy. <10> A vehicle as described in.

[0217] <12> <7> from <9> A stationary power source comprising the battery pack according to any one of claims 1 to 5. [Explanation of symbols]

[0218] Reference Signs List 1...battery, 1a...electrode group, 1b...electrode, 2...current collector, 2a...metal fiber, 2b...active material-containing portion, 2c...void, 3...negative electrode, 3a...negative electrode current collector, 3b...negative electrode active material-containing layer, 4...separator, 5...positive electrode, 5a...positive electrode current collector, 5b...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...exterior member, 21...sealing plate, 22...control valve, 23...filling port, 24...sealing plug, 31...container, 32...lid, 33...protective sheet, 34...printed wiring 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 network, 117... communication network, 118... power conversion device, 121... consumer side EMS, 122... power conversion device, 123... stationary power supply, 200... battery pack, 201... bus bar, 206... negative side lead, 207... positive side lead, 300... battery pack, 300A... battery pack, 300B... battery pack, 342... positive side connector, 342a... wiring, 343... negative side connector, 343a... wiring, 345... thermistor, 346... protection circuit, 348a... positive side wiring, 348b... negative side wiring, 350... external terminal for energizing, 352... positive side terminal, 353... negative side terminal, 400... vehicle.

Claims

1. A first current collector having a porosity of 70% or more and 90% or less; An electrode comprising the current collector and an active material-containing portion, the second porosity being 60% or more and 80% or less.

2. The electrode according to claim 1 , wherein the active material-containing portion is supported on the current collector.

3. The electrode of claim 1 , wherein the current collector comprises metal fibers.

4. The electrode according to claim 3 , wherein the metal fibers have a fiber diameter of 1 μm or more and 100 μm or less.

5. The electrode according to claim 1 , wherein the current collector has a thickness of 1 mm or more and 50 mm or less.

6. A positive electrode and A negative electrode; An electrolyte; 3. A secondary battery comprising: a positive electrode and a negative electrode, the positive electrode and the negative electrode being the electrode according to claim 1 or 2.

7. A battery pack comprising the secondary battery according to claim 6.

8. An external terminal for supplying electricity; A protection circuit; The battery pack of claim 7 further comprising:

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

10. A vehicle comprising the battery pack according to claim 7.

11. The vehicle of claim 10 including a mechanism for converting kinetic energy of the vehicle into regenerative energy.

12. A stationary power source comprising the battery pack according to claim 7.

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