Conductive substrate and secondary battery

Abstract

The conductive substrate includes: a holding body containing an amorphous first super engineering plastic; and a plurality of covering particles dispersed inside the holding body, including a central portion containing a conductive material and a covering portion covering the central portion and containing a crystalline second super engineering plastic.

Description

Technical Field

[0001] The present technology relates to a conductive substrate and a secondary battery. Background Art

[0002] Since various electronic devices such as mobile phones are becoming popular, development of a secondary battery as a small, lightweight, and high-energy-density power source is underway. As such a secondary battery, a bipolar secondary battery has been proposed in which current flows longitudinally (layer stacking direction of the electrodes) via a conductive substrate (current collector). This is because the conduction path of electrons is shortened and a high battery voltage can be obtained.

[0003] Various studies have been conducted on the structure of the current collector for a bipolar secondary battery. Specifically, in order to prevent short circuits and suppress an increase in resistance, a conductive resin layer is disposed between a pair of conductive ion blocking layers, and the conductive resin layer is electrically joined to the pair of conductive ion blocking layers (for example, refer to Patent Document 1). In addition, in order to obtain high electron conductivity, a conductive material is embedded in an organic structure to obtain at least electron conductivity in the film thickness direction (for example, refer to Patent Document 2).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2010-277862

[0007] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2010-073500 Summary of the Invention

[0008] To solve technical problems related to bipolar secondary batteries, various studies have been conducted, but since countermeasures for balancing electrical characteristics and physical characteristics are still insufficient, there is room for improvement.

[0009] The present technology has been proposed in view of the above problems, and an object thereof is to provide a conductive substrate and a secondary battery that can balance electrical characteristics and physical characteristics.

[0010] A conductive substrate according to an embodiment of the present technology includes: a holding body containing an amorphous first super engineering plastic; and a plurality of covering particles dispersed inside the holding body, including a central portion containing a conductive material and a covering portion covering the central portion and containing a crystalline second super engineering plastic.

[0011] A secondary battery according to an embodiment of the present technology includes the conductive substrate according to an embodiment of the present technology as a current collector.

[0012] A conductive substrate or a secondary battery according to an embodiment of the present technology. In this conductive substrate, a plurality of covering particles are dispersed inside a holding body (an amorphous first super engineering plastic). The covering particles include a central portion (a conductive material) and a covering portion (a crystalline second super engineering plastic). Therefore, both electrical properties and physical properties can be taken into account.

[0013] It should be noted that the effects of the present technology are not limited to the effects described herein, and may also be any of a series of effects related to the present technology described later. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a cross-sectional view schematically showing the configuration of a conductive substrate in an embodiment of the present technology.

[0015] Figure 2 It is a cross-sectional view showing the configuration of a secondary battery in an embodiment of the present technology. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Hereinafter, an embodiment of the present technology will be described in detail with reference to the drawings. It should be noted that the order of description is as follows.

[0017] 1. Conductive substrate

[0018] 1-1. Configuration

[0019] 1-2. Operation

[0020] 1-3. Manufacturing method

[0021] 1-4. Function and effect

[0022] 2. Secondary battery

[0023] 2-1. Configuration

[0024] 2-2. Operation

[0025] 2-3. Manufacturing method

[0026] 2-4. Function and effect

[0027] 3. Variation

[0028] <1. Conductive substrate>

[0029] First, a conductive substrate according to an embodiment of the present technology will be described.

[0030] The conductive substrate described herein is a support having conductivity. This conductive substrate is used to support the supported body and ensure the conductivity (electronic conductivity) of the supported body.

[0031] The use of the conductive substrate is not particularly limited. Specifically, it is an electrode of an electronic device that requires current collection, and the type of the electronic device is not particularly limited. Specifically, it is a battery, a capacitor, etc. In addition, the battery can be a primary battery or a secondary battery. When the use of the conductive substrate is an electronic device, the above-mentioned supported body is an active material layer that undergoes an electrode reaction. When the electronic device is a secondary battery, the above-mentioned electrode reaction is a charge-discharge reaction.

[0032] <1-1. Configuration>

[0033] Figure 1 The cross-sectional configuration of the conductive substrate in one embodiment of the present technology is schematically shown. In Figure 1 , in order to easily understand the configuration of the conductive substrate, the dimensions of the conductive substrate (the length in the X-axis direction and the thickness in the Z-axis direction) and the dimensions of the covering particles 20 (particle diameters) are deformed (appropriately adjusted).

[0034] As Figure 1 shown, the conductive substrate includes a holding body 10 and a plurality of covering particles 20.

[0035] [Holding body]

[0036] The holding body 10 holds the plurality of covering particles 20 in a state where the plurality of covering particles 20 are dispersed therein.

[0037] The holding body 10 contains any one or more of non-crystalline first super engineering plastics (hereinafter referred to as "first SEP"). "Super engineering plastics" refers to a general term for high heat-resistant plastics (high heat-resistant resins) that can continuously exhibit functions based on physical properties, etc. even in a high-temperature environment of about 150 °C or higher. "First SEP" refers to a super engineering plastic having non-crystallinity among the above-mentioned super engineering plastics.

[0038] From Figure 1 it can be seen that the holding body 10 is the matrix of the conductive substrate that holds the plurality of covering particles 20. Thus, the holding body 10 containing first SEP mainly functions to ensure the physical properties of the conductive substrate.

[0039] Specifically, first SEP has non-crystallinity, that is, it does not have crystallinity due to the random arrangement of molecular chains. Therefore, it has excellent physical properties from the viewpoints of physical properties such as tensile strength and flexural modulus.

[0040] Thus, in the holding body 10 containing the first SEP, flexibility (or flexibility) can be ensured because hardening and embrittlement can be suppressed, so that the physical durability (physical strength) of the conductive substrate can be ensured by the holding body 10. In this case, in particular, even if the content (dispersion amount) of the plurality of central portions 21 in the holding body 10 described later increases, the physical strength of the conductive substrate can be ensured.

[0041] Therefore, the holding body 10 can prevent the conductive substrate from being damaged. The damage of the conductive substrate refers to the occurrence of cracks, breakage of the conductive substrate, and collapse of the conductive substrate.

[0042] The type of the first SEP is not particularly limited as long as it is any one or two or more of amorphous super engineering plastics. Specific examples of the first SEP are polyetherimide (Polyetherimide (PEI)), polysulfone (Polysulfone (PSU)), polyphenylsulfone (PolyPhenylSulfone (PPSU)), and polyarylate (Polyarylate (PAR)).

[0043] It should be noted that the dimensions of the conductive substrate (length in the X-axis direction, width in the Y-axis direction, and thickness in the Z-axis direction) are mainly determined by the length, width, and thickness of the holding body 10. The length, width, and thickness of the holding body 10 are not particularly limited and can be arbitrarily set according to the use of the conductive substrate.

[0044] In this case, since the thickness of the holding body 10 is small enough, the conductive substrate can be a flexible film, and since the thickness of the holding body 10 is large enough, the conductive substrate can be a rigid plate.

[0045] [Multiple covering particles]

[0046] A plurality of covering particles 20 are dispersed inside the holding body 10 and held by the holding body 10. The covering particle 20 includes a central portion 21 and a covering portion 22.

[0047] (Central portion)

[0048] The central portion 21 contains any one or two or more of conductive materials. Thus, the central portion 21 containing the conductive material mainly functions to ensure the conductivity of the conductive substrate and is a so-called conductive filler.

[0049] The shape of the central portion 21 is not particularly limited. Specifically, it is any one or two or more of spherical (including elliptical), needle-shaped, plate-shaped, flaky, tubular, fibrous, rod-shaped, and irregular shapes. Figure 1In [the figure], in order to simplify the illustration of the central portion 21, the shape of the central portion 21 is set to a spherical shape.

[0050] The type of the conductive material is not particularly limited. Specifically, it is a carbon material, a metal material, etc. This is because excellent conductivity can be obtained.

[0051] The carbon material is carbon nanofiber, carbon black, porous carbon, fullerene, graphene, carbon nanotube, carbon microcoil, etc. The carbon nanofiber is vapor grown carbon fiber (VGCF), etc. The carbon black is Ketjen black, acetylene black, etc. The carbon nanotube is single wall carbon nanotube (SWCNT), multi wall carbon nanotube (MWCNT), etc. The metal material is nickel, stainless steel, etc.

[0052] Among them, the shape of the central portion 21 is preferably fibrous. This is because, inside the holding body 10, the central portions 21 are easily electrically connected to each other and it is easy to form a conductive path (electron conduction path), so the conductivity of the conductive matrix is improved. Therefore, the conductive material is preferably a fibrous carbon material. More specifically, it is preferably carbon nanofiber, carbon nanotube, etc.

[0053] It should be noted that the size (average particle diameter and average length) of the central portion 21 is not particularly limited, and thus can be arbitrarily set according to the use of the conductive matrix, etc. This "average particle diameter" is the median particle diameter D50 (μm).

[0054] (Covering portion)

[0055] The covering portion 22 covers the surface of the central portion 21. The covering portion 22 can cover the entire surface of the central portion 21, or can cover only a part of the surface of the central portion 21. In the latter case (covering a part), the surface of the central portion 21 can also be covered by a plurality of covering portions 22 separated from each other at a plurality of positions.

[0056] In addition, the covering portion 22 contains any one or more of crystalline second super engineering plastics (hereinafter referred to as "second SEP"). The "second SEP" refers to the super engineering plastics having crystallinity among the above-mentioned super engineering plastics.

[0057] From Figure 1 it can be seen that the covering portion 22 is interposed between the holding body 10 and the central portion 21 to cover the surface of the central portion 21. Thus, the covering portion 22 containing the second SEP mainly electrochemically protects the surface of the central portion 21, thereby functioning to ensure the electrical characteristics of the conductive matrix.

[0058] Specifically, the second SEP has crystallinity, that is, the molecular chains are regularly arranged, so it has excellent physical properties from the viewpoint of electrochemical stability.

[0059] Thus, in the covering portion 22 containing the second SEP, electrochemical resistance is ensured due to the reduced reactivity, so that the covering portion 22 can suppress side reactions from occurring on the surface of the central portion 21. In this case, in particular, in applications such as electronic devices, if a conductive substrate is used together with an electrolyte, the decomposition reaction of the electrolyte on the surface of the central portion 21 can be suppressed.

[0060] Therefore, when the conductive substrate is applied to an electronic device having an electrolyte, the electrochemical stability of the central portion 21 is improved by the covering portion 22, so that the electrical characteristics of the conductive substrate are improved.

[0061] The type of the second SEP is not particularly limited as long as it is any one or two or more of super engineering plastics having crystallinity. Specific examples of the second SEP are polyphenylene sulfide (Polyphenylenesulfide (PPS)), polyether ether ketone (Polyetheretherketone (PEEK)), polyether sulfone (Polyethersulfone (PES)), and polyamideimide (Polyamideimide (PAI)).

[0062] It should be noted that the size of the covering portion 22 (the covering thickness, which is the size in the covering direction of the surface of the central portion 21) is not particularly limited, so it can be arbitrarily set according to the use of the conductive substrate and the like.

[0063] [Mixing ratio]

[0064] Here, the mixing ratio of the holding body 10 (the first SEP) and the plurality of central portions 21 (conductive materials) is not particularly limited. Among them, it is preferable that the content of the plurality of central portions 21 in the conductive substrate is sufficiently small. Specifically, it is preferably 5% by weight to 25% by weight, and more preferably 5% by weight to 20% by weight. This is because while suppressing the stiffening and embrittlement of the holding body 10, sufficient conductivity can be obtained by the plurality of central portions 21, so it is easy to balance ensuring physical strength and ensuring conductivity in the conductive substrate.

[0065] When the total weight of the holding body 10 and the weight of the covering portion 22 is set to 100% by weight, the content of the plurality of central portions 21 in the conductive substrate described herein indicates what percentage by weight the weight of the plurality of central portions 21 corresponds to.

[0066] In addition, the mixing ratio of the holding body 10 (first SEP) and the plurality of covering parts 22 (second SEP) is not particularly limited. Among them, it is preferable that the ratio R1 of the weight of the holding body 10 to the total weight of the holding body 10 and the plurality of covering parts 22 is greater than the ratio R2 of the weight of the plurality of covering parts 22 to the total weight of the holding body 10 and the plurality of covering parts 22. This is because while the reactivity of the surface of the central part 21 is sufficiently suppressed by the covering part 22, sufficient flexibility can be obtained through the holding body 10. Therefore, it is easy to balance ensuring physical strength and ensuring electrochemical stability in the conductive substrate.

[0067] <1-2. Operation>

[0068] In this conductive substrate, conductivity is exhibited by the central part 21 (conductive material) of each of the plurality of covering particles 20.

[0069] In this case, as described above, since the covering part 22 (second SEP) covers the surface of the central part 21, side reactions occurring on the surface of the central part 21 can be suppressed by this covering part 22. In addition, since a plurality of covering particles 20 (central part 21 and covering part 22) are dispersed inside the holding body 10 (first SEP), flexibility of the conductive substrate can be ensured by this holding body 10.

[0070] <1-3. Manufacturing method>

[0071] When manufacturing the conductive substrate, as described below, after producing a plurality of covering particles 20, the plurality of covering particles 20 are used to produce the conductive substrate.

[0072] First, a mixture is obtained by mixing a plurality of central parts 21 (powdered conductive material) and a plurality of particles (second SEP). Next, using a melt extrusion molding machine such as a twin-screw extruder, the mixture is kneaded while being heated, and the mixture is molded. In this case, the mixture is heated at a temperature higher than the melting temperature (melting point) of the second SEP to melt the second SEP.

[0073] Thereby, since a plurality of central parts 21 are dispersed in the melt of the second SEP, the melt of the second SEP adheres to the surface of each central part 21. Therefore, the covering part 22 containing the second SEP is formed so as to cover the surface of the central part 21, and a plurality of covering particles 20 including the central part 21 and the covering part 22 are produced.

[0074] Next, a mixture is obtained by mixing a plurality of covering particles 20 and a plurality of particles (first SEP). Next, using an extrusion molding machine such as a T mold extrusion molding machine, the mixture is kneaded while being heated, and the mixture is formed into a film shape or a plate shape. In this case, by heating the mixture at a temperature higher than the melting temperature (melting point) of the first SEP, the first SEP is melted.

[0075] Thereby, while dispersing a plurality of covering particles 20 in the melt of the first SEP, the melt of the first SEP is formed into a film shape or a plate shape. Therefore, a plurality of covering particles 20 are held by the holding body 10 containing the first SEP, and a conductive substrate including the holding body 10 and the plurality of covering particles 20 is completed.

[0076] <1-4. Action and effect>

[0077] According to this conductive substrate, a plurality of covering particles 20 are dispersed inside the holding body 10 (non-crystalline first SEP), and the covering particles 20 include a central portion 21 (conductive material) and a covering portion 22 (crystalline second SEP).

[0078] In this case, as described above, conductivity is ensured by the central portion 21 (conductive material), flexibility is ensured by the holding body 10 (first SEP), and side reactions are suppressed by the covering portion 22 (second SEP). Thereby, by ensuring flexibility, the physical properties of the conductive substrate are stabilized, and by suppressing side reactions, the electrical properties of the electronic device using the conductive substrate are improved. Therefore, both electrical properties and physical properties can be achieved.

[0079] In particular, if the first SEP contains polyetherimide or the like and the second SEP contains polyphenylene sulfide or the like, sufficient flexibility can be obtained by the holding body 10, and side reactions can be sufficiently suppressed by the covering portion 22, so higher effects can be obtained.

[0080] In addition, if the conductive material contains a fibrous carbon material, the conductivity of the conductive substrate is improved because a conductive path is easily formed, so higher effects can be obtained.

[0081] In addition, if the ratio R1 is greater than the ratio R2, it is easy to balance ensuring physical strength and ensuring electrochemical stability in the conductive substrate, so higher effects can be obtained.

[0082] <2. Secondary battery>

[0083] Next, as an example of the use of the above-mentioned conductive substrate, a secondary battery according to an embodiment of the present technology will be described. In this secondary battery, the conductive substrate is used as a current collector for an electrode.

[0084] The secondary battery described herein is a bipolar secondary battery having a current collector, a positive electrode active material layer, and a negative electrode active material layer. In this secondary battery, the battery capacity is obtained by the insertion and extraction of electrode reaction substances. In this case, in order to prevent the electrode reaction substances from precipitating on the surface of the negative electrode active material layer during charging, the charging capacity of the negative electrode active material layer is greater than the discharging capacity of the positive electrode active material layer. That is, the electrochemical capacity per unit area of the negative electrode active material layer is set to be greater than the electrochemical capacity per unit area of the positive electrode active material layer.

[0085] The type of the electrode reaction substance is not particularly limited, and it is a light metal such as an alkali metal and an alkaline earth metal. The alkali metals are lithium, sodium, potassium, etc., and the alkaline earth metals are beryllium, magnesium, calcium, etc.

[0086] Hereinafter, the case where the electrode reaction substance is lithium will be taken as an example. A secondary battery that obtains the battery capacity by the insertion and extraction of lithium is a so-called lithium ion secondary battery. In this lithium ion secondary battery, lithium is inserted and extracted in an ionic state.

[0087] <2-1. Configuration>

[0088] Figure 2 The cross-sectional configuration of the secondary battery in one embodiment of the present technology is shown. As Figure 2 shown, this secondary battery includes a battery element 30, a positive electrode lead 40, and a negative electrode lead 50.

[0089] [Battery element]

[0090] The battery element 30 is the main part that performs the electrode reaction, that is, the charge and discharge reaction of the secondary battery. This battery element 30 mainly has a multilayer structure in which electrodes 31 are alternately laminated with a separator 32 and an electrolyte layer 33 in the height direction (Z-axis direction). More specifically, the electrodes 31 are alternately laminated with the separator 32, and the electrolyte layer 33 is interposed between the electrodes 31 and the separator 32. Here, the battery element 30 includes a plurality of electrodes 31, a plurality of separators 32, and a plurality of electrolyte layers 33.

[0091] (Electrode)

[0092] The electrode 31 includes a current collector 31A, a positive electrode active material layer 31B, and a negative electrode active material layer 31C. The current collector 31A has a pair of surfaces (one surface and the other surface) facing in opposite directions. The positive electrode active material layer 31B is disposed on one surface of the current collector 31A, and the negative electrode active material layer 31C is disposed on the other surface of the current collector 31A. That is, the electrode 31 is a double-sided electrode in which the active material layers (the positive electrode active material layer 31B and the negative electrode active material layer 31C) are disposed on both surfaces of the current collector 31A. The configuration of the current collector 31A is the same as that of the above-described conductive substrate.

[0093] Since the positive electrode active material layer 31B, the current collector 31A, and the negative electrode active material layer 31C are stacked in this order, the current collector 31A is sandwiched between the positive electrode active material layer 31B and the negative electrode active material layer 31C having opposite polarities to each other. As described above, the electrode 31 is a bipolar electrode including the positive electrode active material layer 31B and the negative electrode active material layer 31C having opposite polarities to each other.

[0094] In addition, among the plurality of electrodes 31, the electrode 31 closest to the positive electrode lead 40 (the lowermost electrode 31 in the height direction) is a single-sided electrode in which the negative electrode active material layer 31C is not disposed on the current collector 31A and only the positive electrode active material layer 31B is disposed. This is because the positive electrode active material layer 31B is electrically connected to the positive electrode lead 40 via the current collector 31A.

[0095] In addition, among the plurality of electrodes 31, the electrode 31 closest to the negative electrode lead 50 (the uppermost electrode 31 in the height direction) is a single-sided electrode in which the positive electrode active material layer 31B is not disposed on the current collector 31A and only the negative electrode active material layer 31C is disposed. This is because the negative electrode active material layer 31C is electrically connected to the negative electrode lead 50 via the current collector 31A.

[0096] Here, in other words, the battery element 30 has a multilayer structure in which the electrode elements 34 are alternately stacked in the height direction with the current collector 31A interposed therebetween, such that the uppermost layer and the lowermost layer are the current collector 31A respectively. Here, the battery element 30 includes a plurality of electrode elements 34 and a plurality of current collectors 31A.

[0097] The electrode element 34 includes a current collector 31A, a positive electrode active material layer 31B disposed on one surface of the current collector 31A with the electrolyte layer 33 interposed therebetween, and a negative electrode active material layer 31C disposed on the other surface of the current collector 31A with the electrolyte layer 33 interposed therebetween.

[0098] That is, the positive electrode active material layer 31B, the electrolyte layer 33, the separator 32, the electrolyte layer 33, and the negative electrode active material layer 31C are stacked in this order. Thus, the separator 32 is disposed between the positive electrode active material layer 31B and the negative electrode active material layer 31C. In addition, the electrolyte layer 33 (the first electrolyte layer) is interposed between the positive electrode active material layer 31B and the separator 32, and the electrolyte layer 33 (the second electrolyte layer) is interposed between the negative electrode active material layer 31C and the separator 32.

[0099] The number of stacked layers of the electrode element 34 is not particularly limited and can be arbitrarily set. In Figure 2 order to simplify the illustration, a case where the number of stacked layers of the electrode element 34 is five is shown.

[0100] The positive electrode active material layer 31B contains any one or two or more of the positive electrode active materials capable of intercalating and deintercalating lithium, and may further contain a positive electrode binder, a positive electrode conductive agent, and the like.

[0101] The type of the positive electrode active material is not particularly limited and is a lithium-containing compound such as a lithium transition metal compound. The lithium transition metal compound contains lithium and one or two or more transition metal elements, and may further contain one or two or more other elements. The type of the other elements can be any element (except for transition metal elements) and is not particularly limited. Among them, the other elements preferably belong to Groups 2 to 15 of the long-period type periodic table. It should be noted that the lithium transition metal compound can be an oxide, or any one of a phosphate compound, a silicate compound, a borate compound, and the like.

[0102] Specific examples of the oxide are LiNiO 2 、LiCoO 2 、LiCo 0.98 Al 0.01 Mg 0.01 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、LiNi 0.8 Co 0.15 Al 0.05 O 2 、LiNi 0.33 Co 0.33 Mn 0.33 O 2 、Li 1.2 Mn 0.52 Co 0.175 Ni 0.1 O 2 、Li 1.15 (Mn 0.65 Ni 0.22Co 0.13 ) 2 、LiMn 2 O 4 and Li 4 Ti 5 O 12 etc. A specific example of the phosphoric acid compound is LiFePO 4 、LiMnPO 4 、LiFe 0.5 Mn 0.5 PO 4 and LiFe 0.3 Mn 0.7 PO 4 wait.

[0103] The positive electrode binder includes any one or two or more of synthetic rubber and polymer compounds, etc. The synthetic rubber is styrene butadiene rubber, etc., and the polymer compound is polyvinylidene fluoride, polyimide, carboxymethyl cellulose, etc.

[0104] The positive electrode conductive agent includes any one or more of conductive materials such as carbon materials. The carbon material is graphite, carbon black, acetylene black, Ketjen black, etc. In addition, the conductive material may also be a metal material and a conductive polymer.

[0105] The negative electrode active material layer 31C contains any one or more negative electrode active materials capable of inserting and releasing lithium, and may further contain a negative electrode binder and a negative electrode conductor, etc. The details of the negative electrode binder and the negative electrode conductor are the same as those of the positive electrode binder and the positive electrode conductor.

[0106] The type of negative electrode active material is not particularly limited, and may be carbon materials and metal materials. Carbon materials include graphitizable carbon, non-graphitizable carbon, and graphite, and the graphite includes natural graphite and artificial graphite. Metal materials are materials containing any one or more of metal elements and semi-metal elements that can form an alloy with lithium, and specific examples of the metal elements and semi-metal elements are silicon and tin. The metal material may be a monomer, an alloy, a compound, a mixture of two or more thereof, or a material containing two or more phases thereof.

[0107] A specific example of a metal-based material is SiB 4 、SiB 6 Mg 2 Si、Ni 2 Si、TiSi 2 、MoSi 2 、CoSi 2 、NiSi 2 、CaSi2 , CrSi 2 , Cu 5 Si, FeSi 2 , MnSi 2 , NbSi 2 , TaSi 2 , VSi 2 , WSi 2 , ZnSi 2 , SiC, Si 3 N 4 , Si 2 N 2 O, SiO v (0 < v ≤ 2 or 0.2 < v < 1.4), LiSiO, SnO w (0 < w ≤ 2), SnSiO 3 , LiSnO and Mg 2 Sn etc.

[0108] (Separator)

[0109] Separator 32 is a porous membrane that separates the positive electrode active material layer 31B and the negative electrode active material layer 31C from each other, and contains any one or more of polymer compounds such as polyethylene and polypropylene. This separator 32 functions as an ion barrier that allows the movement of electrons and prohibits the movement of ions (lithium ions). It should be noted that the separator 32 may also be a non-woven fabric containing any one or more of aromatic polyamide fibers, glass fibers, and nylon fibers.

[0110] (Electrolyte layer)

[0111] Electrolyte layer 33 is a gel-like electrolyte containing an electrolytic solution and a polymer compound, and in this electrolyte layer 33, the electrolytic solution is held by the polymer compound. This is because high ionic conductivity can be obtained and leakage of the electrolytic solution can be prevented.

[0112] The electrolytic solution contains a solvent and an electrolyte salt. The solvent contains any one or more of non-aqueous solvents (organic solvents) such as carbonate-based compounds, carboxylate-based compounds, and lactone-based compounds. The electrolyte salt contains any one or more of light metal salts such as lithium salts. The polymer compound contains any one or more of polyvinylidene fluoride, etc.

[0113] [Positive electrode lead and negative electrode lead]

[0114] As described above, since the positive electrode lead 40 is connected to the electrode 31 (positive electrode active material layer 31B) which is the lowermost layer of the single-sided electrode via the current collector 31A, the positive electrode lead 40 is electrically connected to the positive electrode active material layer 31B. As described above, since the negative electrode lead 50 is connected to the electrode 31 (negative electrode active material layer 31C) which is the uppermost layer of the single-sided electrode via the current collector 31A, the negative electrode lead 50 is electrically connected to the negative electrode active material layer 31C.

[0115] Here, the positive electrode lead 40 extends to the outside of the battery element 30, and the negative electrode lead 50 extends to the outside of the battery element 30 in a direction opposite to the lead-out direction of the positive electrode lead 40. In addition, each of the positive electrode lead 40 and the negative electrode lead 50 may extend in a common direction with each other. Each of the positive electrode lead 40 and the negative electrode lead 50 contains any one or two or more of conductive materials such as aluminum, copper, nickel, and stainless steel. The shapes of the positive electrode lead 40 and the negative electrode lead 50 are each in a thin plate shape, a mesh shape, or the like.

[0116] [Other]

[0117] It should be noted that the secondary battery may further include any one or two or more of other components not shown.

[0118] The other components are an outer packaging member that houses the battery element 30, etc. The outer packaging member may be a rigid metal can, a flexible outer packaging film, or other components. When the battery element 30 is housed inside the outer packaging member, the positive electrode lead 40 and the negative electrode lead 50 are respectively led out from the inside of the outer packaging member to the outside.

[0119] <2-2. Operation>

[0120] When the secondary battery is charged, lithium is deintercalated from the positive electrode active material layer 31B, and this lithium is intercalated into the negative electrode active material layer 31C via the electrolyte layer 33. In addition, when the secondary battery is discharged, lithium is deintercalated from the negative electrode active material layer 31C, and this lithium is intercalated into the positive electrode active material layer 31B via the electrolyte layer 33. During these charge and discharge processes, lithium is intercalated and deintercalated in an ionic state.

[0121] <2-3. Manufacturing method>

[0122] When manufacturing the secondary battery, after manufacturing the electrode element 34 through the steps described below, the secondary battery is manufactured using this electrode element 34.

[0123] [Manufacture of positive electrode active material layer]

[0124] First, a mixture of a positive electrode active material, a positive electrode binder, a positive electrode conductive agent, etc. (positive electrode composite material) is put into a solvent such as an organic solvent, thereby preparing a paste-like positive electrode composite material slurry. Next, the positive electrode composite material slurry is coated on the surface of a release substrate, thereby forming a positive electrode active material layer 31B. This release substrate is a substrate having a release treatment applied to one surface, and this substrate is a metal foil, a polymer film, etc. The details of the release substrate described herein are the same hereinafter. Then, if necessary, the positive electrode active material layer 31B can be compression-molded using a roll press or the like. In this case, the positive electrode active material layer 31B can be heated, or compression molding can be repeated multiple times. Finally, the positive electrode active material layer 31B is peeled off from the release substrate. Additionally, here, the positive electrode active material layer 31B may not be peeled off from the release substrate, but the positive electrode active material layer 31B may be peeled off from the release substrate in the manufacturing process of the electrode element 34 described later.

[0125] [Manufacture of negative electrode active material layer]

[0126] The negative electrode active material layer 31C is manufactured by the same steps as the manufacturing steps of the above-mentioned positive electrode active material layer 31B. Specifically, a mixture of a negative electrode active material, a negative electrode binder, a negative electrode conductive agent, etc. (negative electrode composite material) is put into a solvent such as an organic solvent, thereby preparing a paste-like negative electrode composite material slurry, and then the negative electrode composite material slurry is coated on the surface of a release substrate, thereby forming a negative electrode active material layer 31C. Then, if necessary, the negative electrode active material layer 31C can be compression-molded. Finally, the negative electrode active material layer 31C is peeled off from the release substrate. Additionally, here, the negative electrode active material layer 31C may not be peeled off from the release substrate, but the negative electrode active material layer 31C may be peeled off from the release substrate in the manufacturing process of the electrode element 34 described later.

[0127] [Manufacture of electrolyte layer]

[0128] First, an electrolyte salt is added to a solvent to prepare an electrolytic solution. Next, a sol-like coating solution is prepared by mixing a polymer compound, the electrolytic solution, and an organic solvent added as needed. Finally, the coating solution is coated on the surface of the positive electrode active material layer 31B to manufacture a gel-like electrolyte layer 33, and the coating solution is coated on the surface of the negative electrode active material layer 31C to manufacture a gel-like electrolyte layer 33.

[0129] [Manufacture of electrode element]

[0130] First, a positive electrode active material layer 31B formed with an electrolyte layer 33, a separator 32, and a negative electrode active material layer 31C formed with an electrolyte layer 33 are sequentially laminated on a release substrate to fabricate a laminate. In this case, the electrolyte layers 33 face each other with the separator 32 therebetween. Next, using a press or the like, the laminate is pressed (hot-pressed) while being heated in the lamination direction. Conditions such as the heating temperature and the pressing pressure during hot pressing can be arbitrarily set. The details of the hot pressing described herein are the same hereinafter. Thereby, the positive electrode active material layer 31B is bonded to the separator 32 via the electrolyte layer 33, and the negative electrode active material layer 31C is bonded to the separator 32 via the electrolyte layer 33, thereby fabricating an electrode element 34. Finally, the release substrate is peeled off from the electrode element 34 (the positive electrode active material layer 31B and the negative electrode active material layer 31C).

[0131] [Assembly of Secondary Battery]

[0132] First, the electrode elements 34 are alternately laminated on the release substrate with the current collector 31A therebetween to fabricate a laminate. In this case, the lowermost layer and the uppermost layer are each the current collector 31A. Next, the laminate is hot-pressed in the lamination direction using a press or the like. Thereby, the electrode elements 34 are bonded to each other via the current collector 31A, thereby fabricating a battery element 30. Next, the release substrate is peeled off from the battery element 30. Finally, a positive electrode lead 40 is connected to the lowermost current collector 31A using a welding method or the like, and a negative electrode lead 50 is connected to the uppermost current collector 31A using a welding method or the like. This welding method is any one or two or more of a laser welding method and a resistance welding method or the like.

[0133] [Stabilization of Secondary Battery]

[0134] The assembled secondary battery is charged and discharged. Various conditions such as the ambient temperature, the number of charge-discharge cycles (cycle number), and the charge-discharge conditions can be arbitrarily set. Therefore, a coating film is formed on the surface of the negative electrode active material layer 31C or the like, thereby electrochemically stabilizing the state of the secondary battery. Therefore, a secondary battery using the electrode element 34, that is, a bipolar secondary battery, is completed.

[0135] <2-4. Action and Effect>

[0136] According to this secondary battery, the current collector 31A has the same configuration as that of the above-described conductive substrate. In this case, as described above, by ensuring flexibility, the physical properties of the current collector 31A are stabilized, and by suppressing side reactions (decomposition reactions of the electrolyte), the electrical properties of the secondary battery using the current collector 31A are improved. Therefore, in the current collector 31A, both electrical properties and physical properties can be taken into account, and thus excellent cycle characteristics can be obtained.

[0137] In this case, in particular, by suppressing the decomposition reaction of the electrolytic solution, the amount of formation of the unnecessary coating film caused by the reductive decomposition of the electrolytic solution is reduced. Therefore, even when the secondary battery is exposed to a reducing atmosphere, the resistance is not likely to increase. Thus, sufficiently stable cycle characteristics can be obtained.

[0138] It should be noted that the other functions and effects of the secondary battery are the same as those of the above-mentioned conductive substrate.

[0139] <3. Modification example>

[0140] Next, modification examples of the above-mentioned conductive substrate and secondary battery will be described. The respective configurations of the conductive substrate and secondary battery can be appropriately changed as described below. In addition, any two or more of the series of modification examples described below can be combined with each other.

[0141] [Modification example 1]

[0142] As the electrolyte serving as a medium for the charge-discharge reaction, the electrolyte layer 33 which is a gel-like electrolyte is used. However, the electrolytic solution which is a liquid electrolyte can also be directly used instead of the electrolyte layer 33.

[0143] The configuration of the secondary battery using the electrolytic solution is the same as that of the secondary battery using the electrolyte layer 33 except that the electrolyte layer 33 is omitted and the electrolytic solution infiltrates into each of the positive electrode active material layer 31B, the negative electrode active material layer 31C, and the separator 32.

[0144] The manufacturing method of the secondary battery using the electrolytic solution is the same as that of the secondary battery using the electrolyte layer 33 except that the laminate is produced without using the electrolyte layer 33 and then the electrolytic solution is infiltrated into the laminate. It should be noted that in the case of using the outer packaging member for housing the battery element 30, the laminate is housed inside the bag-shaped outer packaging member, and then the electrolytic solution is injected into the inside of the bag-shaped outer packaging member so that the electrolytic solution infiltrates into the laminate.

[0145] Even in this case, since lithium is intercalated and deintercalated via the electrolytic solution in each of the positive electrode active material layer 31B and the negative electrode active material layer 31C, the same effects can be obtained.

[0146] [Modification example 2]

[0147] A porous membrane is used as the separator 32. However, the separator 32 can also have a multilayer structure including a porous membrane and a polymer compound layer.

[0148] The separator 32 having a multilayer structure includes a porous membrane having a pair of surfaces (one surface and the other surface) facing in opposite directions, and a polymer compound layer disposed on one or both of the one surface and the other surface of the porous membrane. This is because the porous membrane easily adheres to one or both of the positive electrode active material layer 31B and the negative electrode active material layer 31C via the polymer compound layer. Thus, since the lamination misalignment of the battery element 30 is not likely to occur, even if a decomposition reaction of the electrolyte solution or the like occurs, the battery element 30 is not likely to expand.

[0149] The polymer compound layer contains a polymer compound and a plurality of inorganic particles, and the plurality of inorganic particles are dispersed in the polymer compound. This is because when the secondary battery generates heat, the plurality of inorganic particles dissipate heat, so the heat resistance and safety of the secondary battery are improved. The polymer compound includes any one or two or more of polyvinylidene fluoride and the like. The plurality of inorganic particles include any one or two or more of inorganic materials such as aluminum oxide (aluminum trioxide), aluminum nitride, boehmite, silicon oxide (silicon dioxide), titanium oxide (titanium dioxide), magnesium oxide (magnesia), and zirconium oxide (zirconium dioxide).

[0150] Even in this case, the positive electrode active material layer 31B and the negative electrode active material layer 31C are separated from each other with the separator 32 interposed therebetween, allowing the movement of electrons and prohibiting the movement of ions, so that the same effect can be obtained. In this case, in particular, as described above, the expansion of the secondary battery caused by the expansion of the battery element 30 can be suppressed, and the heat resistance and safety of the secondary battery are improved.

[0151] It should be noted that the plurality of inorganic particles are not only contained in the polymer compound but also can be contained in the porous membrane. This is because the expansion of the secondary battery can be further suppressed, and the heat resistance and safety of the secondary battery can be further improved.

[0152] Examples

[0153] Examples of the present technology will be described.

[0154] (Experimental Examples 1 to 7)

[0155] As described below, a conductive substrate ( Figure 1 ) was produced, and a bipolar secondary battery ( Figure 2 ) was produced using the conductive substrate (current collector 31A), and then the physical properties of the conductive substrate and the battery characteristics of the secondary battery were evaluated.

[0156] [Production of Conductive Substrate]

[0157] First, a mixture is obtained by mixing a plurality of central portions 21 (a plurality of VGCFs as a conductive material, average diameter = 0.15 μm, average length = 10 μm) and a plurality of particles (second SEP). As the second SEP, polyphenylene sulfide (PPS) and polyether ether ketone (PEEK) are used.

[0158] In this case, as shown in Table 1, the mixing ratio (weight ratio) of the plurality of central portions 21 and the plurality of particles (second SEP) is adjusted. Regarding the mixing ratio of the plurality of central portions 21, the mixing ratio of the plurality of central portions 21 is adjusted so that the content (weight %) of the plurality of central portions 21 in the final conductive matrix becomes the value shown in Table 1. Regarding the mixing ratio of the plurality of particles (second SEP), the mixing ratio of the plurality of particles is adjusted so that the ratio R2 becomes the value shown in Table 1.

[0159] Next, the mixture is put into a melt extrusion molding machine (twin-screw extruder), and then the mixture is kneaded while being heated (heating temperature = 320 °C or higher) using the extrusion molding machine, thereby molding the mixture. In this case, the heating temperature is adjusted according to the type of the second SEP. As a result, the covering portion 22 containing the second SEP is formed so as to cover the surface of the central portion 21, and thus a plurality of covered particles 20 including the central portion 21 and the covering portion 22 are obtained.

[0160] Next, a mixture is obtained by mixing a plurality of covered particles 20 and a plurality of particles (first SEP). As the first SEP, polyetherimide (PEI) and polysulfone (PSU) are used.

[0161] In this case, as shown in Table 1, the mixing ratio (weight ratio) of the plurality of covered particles 20 and the plurality of particles (first SEP) is adjusted. Regarding the mixing ratio of the plurality of particles (first SEP), the mixing ratio of the plurality of particles is adjusted so that the ratio R1 becomes the value shown in Table 1.

[0162] Finally, the mixture is put into an extrusion molding machine (T-die extrusion molding machine), and then the mixture is kneaded while being heated (heating temperature = 320 °C or higher) using the extrusion molding machine, thereby extruding and molding the mixture into a film shape. In this case, the heating temperature is adjusted according to the type of the first SEP. As a result, since a plurality of covered particles 20 are dispersed in the holding body 10 containing the first SEP, a conductive matrix including the holding body 10 and the plurality of covered particles 20 is completed.

[0163] Note that, for comparison, as shown in Table 1, a conductive substrate was fabricated through the same steps except that a plurality of particles (second SEP) used as the forming material of the covering portion 22 were not used, and a second SEP (PPS) was used instead of the first SEP as the forming material of the holding body 10. Additionally, for comparison, a conductive substrate was fabricated through the same steps except that a plurality of particles (second SEP) used as the forming material of the covering portion 22 were not used. In these cases, since the covering portion 22 was not formed, a conductive substrate including the holding body 10 and a plurality of central portions 21 was fabricated.

[0164] [Fabrication of a secondary battery]

[0165] Through the following steps, a secondary battery was fabricated using the above-mentioned conductive substrate as the current collector 31A.

[0166] [Fabrication of the positive electrode active material layer]

[0167] First, a positive electrode composite material was prepared by mixing 96 parts by mass of a positive electrode active material (lithium cobaltate (LiCoO 2 )), 3 parts by mass of a positive electrode binder (polyvinylidene fluoride), and 1 part by mass of a positive electrode conductive agent (carbon black). Next, the positive electrode composite material was put into a solvent (N-methyl-2-pyrrolidone as an organic solvent), and then the solvent was stirred to prepare a paste-like positive electrode composite material slurry. Next, the positive electrode composite material slurry was coated on the surface of a release substrate (release film), and then the positive electrode composite material slurry was dried to form a positive electrode active material layer 31B. Finally, the positive electrode active material layer 31B was compression-molded using a roll press and then vacuum-dried.

[0168] [Fabrication of the negative electrode active material layer]

[0169] First, a negative electrode composite material was prepared by mixing 90 parts by mass of a negative electrode active material (artificial graphite) and 10 parts by mass of a negative electrode binder (polyvinylidene fluoride). Next, the negative electrode composite material was put into a solvent (N-methyl-2-pyrrolidone as an organic solvent), and then the solvent was stirred to prepare a paste-like negative electrode composite material slurry. Next, the negative electrode composite material slurry was coated on the surface of a release substrate (release film), and then the negative electrode composite material slurry was dried to form a negative electrode active material layer 31C. Finally, the negative electrode active material layer 31C was compression-molded using a roll press and then vacuum-dried.

[0170] [Fabrication of the electrolyte layer]

[0171] First, an electrolyte salt (lithium hexafluorophosphate (LiPF 6)) was added to a solvent (ethylene carbonate and propylene carbonate), and then the solvent was stirred. The mixing ratio (weight ratio) of the solvent was ethylene carbonate:propylene carbonate=50:50, and the content of the electrolyte salt was 1 mol / kg relative to the solvent.

[0172] Next, 2 parts by mass of the polymer compound (polyvinylidene fluoride), 31 parts by mass of the electrolyte, and 67 parts by mass of an additional solvent (dimethyl carbonate as an organic solvent) were mixed and then stirred to prepare a sol-like coating solution.

[0173] Finally, the coating solution is applied to the surface of the positive electrode active material layer 31B formed on the release film, and then the coating solution is dried (the added solvent is volatilized and removed), thereby producing the electrolyte layer 33. In addition, the coating solution is applied to the surface of the negative electrode active material layer 31C formed on the release film, and then the coating solution is dried (the added solvent is volatilized and removed), thereby producing the electrolyte layer 33.

[0174] [Fabrication of electrode elements]

[0175] First, the positive electrode active material layer 31B and the electrolyte layer 33 formed on the release film, and the negative electrode active material layer 31C and the electrolyte layer 33 formed on the release film were stacked on each other through the separator 32 (microporous polyethylene film, thickness = 15 μm), thereby producing a laminate. Next, the laminate was hot-pressed using a press (heating temperature = 105° C., pressing time = 3 seconds), thereby producing an electrode element 34. Finally, the release film was peeled off from the electrode element 34 (positive electrode active material layer 31B and negative electrode active material layer 31C).

[0176] [Assembly of secondary battery]

[0177] First, the electrode elements 34 are alternately stacked with the collector 31A (conductive substrate) in such a way that the bottom layer and the top layer are respectively the collectors 31A, thereby making a laminate. In this case, the number of stacked electrode elements 34 is 5. Next, the laminate is hot-pressed using a press (heating temperature = 105°C, stamping time = 3 seconds). Finally, the positive lead 40 (stainless steel) is connected to the collector 31A of the bottom layer using a laser welding method, and the negative lead 50 (stainless steel) is connected to the collector 31A of the top layer using a laser welding method.

[0178] [Stabilization of secondary batteries]

[0179] In a normal temperature environment (temperature = 23 °C), charge and discharge the secondary battery. During charging, perform constant current charging at a current of 0.1C until the battery voltage reaches 4.45V, and then perform constant voltage charging at this voltage of 4.45V until the current reaches 0.02C. During discharging, perform constant current discharging at a current of 0.1C until the battery voltage reaches 3.0V. 0.1C refers to the current value that fully discharges the battery capacity (theoretical capacity) within 10 hours, and 0.02C refers to the current value that fully discharges the above-mentioned battery capacity within 50 hours.

[0180] Thereby, a coating film is formed on the surface of the negative electrode active material layer 31C, etc., so that the state of the secondary battery is stabilized. Thus, a bipolar secondary battery (lithium ion secondary battery) is completed.

[0181] [Evaluation of Physical Properties of Conductive Substrate and Battery Characteristics of Secondary Battery]

[0182] The physical properties (electrical properties and physical properties) of the conductive substrate were evaluated, and the battery characteristics (cycle characteristics) of the secondary battery were evaluated, and the results shown in Table 1 were obtained.

[0183] (Electrical Properties of Conductive Substrate)

[0184] First, in a normal temperature environment, the resistivity (initial resistivity (Ω·cm)) of the conductive substrate was measured according to JIS K 7194.

[0185] Next, by using the conductive substrate as an electrode, a test secondary battery (half cell) was fabricated that has the conductive substrate as the working electrode and a lithium metal plate as the counter electrode. Next, a reduction floating test was performed using the test secondary battery. Specifically, in a high temperature environment (temperature = 60 °C), continuously charge the test secondary battery. During charging, perform constant current and constant voltage charging during the oxidation reaction until the battery voltage reaches 4.3V (the potential reference of lithium metal), and perform constant current and constant voltage charging during the reduction reaction until the battery voltage reaches 0.0V (the potential reference of lithium metal), thereby charging until the total charging time reaches 100 hours.

[0186] Next, after the reduction floating test is completed, by disassembling the test secondary battery, after recovering the conductive substrate (working electrode) from the test secondary battery, use an organic solvent (dimethyl carbonate and ethanol) to clean the conductive substrate. In this case, clean the conductive substrate with dimethyl carbonate and ethanol in sequence.

[0187] Finally, after measuring the resistivity (post - storage resistivity (Ω·cm)) of the conductive substrate again in a normal temperature environment, calculate the resistivity ratio = post - storage resistivity / initial resistivity.

[0188] (Physical properties of the conductive substrate)

[0189] In accordance with JIS K 7127 "Test methods for tensile properties of plastics - Part 3: Test conditions for films and sheets", the elongation at break (%) of the conductive substrate was measured.

[0190] (Cycling characteristics of the secondary battery)

[0191] First, by charging and discharging the secondary battery in a normal temperature environment, the discharge capacity (discharge capacity of the first cycle) was measured. Next, the charging and discharging of the secondary battery was repeated in the same environment until the number of cycles reached 300 cycles, and thus the discharge capacity (discharge capacity of the 300th cycle) was measured. Finally, the capacity retention rate (%) = (discharge capacity of the 300th cycle / discharge capacity of the first cycle) × 100 was calculated. The charging and discharging conditions were the same as those for stabilizing the secondary battery described above.

[0192] [Table 1]

[0193]

[0194] [Discussion]

[0195] As shown in Table 1, the physical properties (electrical properties and physical properties) of the conductive substrate and the battery characteristics (cycling characteristics) of the secondary battery vary significantly depending on the composition of the conductive substrate.

[0196] Specifically, in the case of using a conductive substrate in which the covering portion 22 containing the first SEP and the second SEP covers the surface of the central portion 21 of the holding body 10 (Experimental Examples 1 to 5), since the resistivity ratio is suppressed, the resistance is not easily increased, and a large elongation at break is obtained, thus ensuring flexibility. Accordingly, in a secondary battery using the conductive substrate (Experimental Examples 1 to 5) as the current collector 31A, a high capacity retention rate was obtained.

[0197] In this case, in particular, when the ratio R1 is greater than the ratio R2 (Experimental Examples 1 and 2), compared with the case where the ratios R1 and R2 are equal to each other (Experimental Example 5), the elongation at break further increases while maintaining a high capacity retention rate.

[0198] In contrast, in the case of using a conductive substrate different from the above-mentioned conductive substrate (Experimental Examples 6 and 7), the resistivity ratio increases or the elongation at break is insufficient.

[0199] Specifically, in the case where the covering portion 22 does not cover the surface of the central portion 21 (Experimental Example 7), although a large elongation at break was obtained, the resistivity ratio increased significantly. Thus, in a secondary battery using the conductive substrate (Experimental Example 7) as the current collector 31A, a high capacity retention rate was not obtained.

[0200] In addition, in the case where the covering portion 22 does not cover the surface of the central portion 21 and the holding body 10 contains the second SEP instead of the first SEP (Experimental Example 6), although the resistivity ratio was suppressed, the elongation at break was 0%. Thus, in a secondary battery using the conductive substrate (Experimental Example 6) as the current collector 31A, the secondary battery was damaged due to insufficient flexibility during charge and discharge, and thus the capacity retention rate could not be calculated.

[0201] [Summary]

[0202] As can be seen from the results shown in Table 1, when the conductive substrate has a plurality of covering particles 20 dispersed inside the holding body 10 (the non-crystalline first SEP), and the covering particles 20 include a central portion 21 (conductive material) and a covering portion 22 (crystalline second SEP), in this conductive substrate, while suppressing the resistance ratio, a large elongation at break was obtained. Therefore, both electrical properties and physical properties are taken into account in the conductive substrate.

[0203] In addition, in a secondary battery using the above-mentioned conductive substrate as the current collector 31A, a high capacity retention rate was obtained. Therefore, excellent cycle characteristics were obtained in the secondary battery.

[0204] One embodiment and examples have been described above to illustrate the present technology, but the structure of the present technology is not limited to the structure described in one embodiment and examples, and various modifications can be made.

[0205] Specifically, the case of using a gel-like electrolyte (electrolyte layer) and a liquid electrolyte (electrolyte solution) has been described, but the type of the electrolyte is not particularly limited, and thus a solid electrolyte (solid electrolyte) can also be used.

[0206] In addition, the case where the electrode reaction material is lithium has been described, but the electrode reaction material is not particularly limited. Specifically, as described above, the electrode reaction material can be other alkali metals such as sodium and potassium, alkaline earth metals such as beryllium, magnesium, and calcium. In addition, the electrode reaction material can also be other light metals such as aluminum.

[0207] The effects described in this specification are merely illustrative, and thus the effects of the present technology are not limited to the effects described in this specification. Therefore, the present technology can also obtain other effects.

Claims

1. A conductive substrate, comprising: A retainer containing an amorphous first super engineering plastic ； And A plurality of covering particles dispersed inside the retainer, including: A central portion containing a conductive material; And a covering portion covering the surface of the central portion and containing a crystalline second super engineering plastic, The first super engineering plastic includes at least one of polyetherimide, polysulfone, polyphenylsulfone, and polyarylate, The second super engineering plastic includes at least one of polyphenylene sulfide, polyether ether ketone, polyether sulfone, and polyamideimide.

2. The conductive substrate according to claim 1, Wherein, The conductive material includes a fibrous carbon material.

3. The conductive substrate according to claim 1 or 2, Wherein, The proportion of the weight of the retainer relative to the sum of the weight of the retainer and the weight of the covering portion is greater than the proportion of the weight of the covering portion relative to the sum of the weight of the retainer and the weight of the covering portion.

4. A secondary battery, Comprising the conductive substrate according to any one of claims 1 to 3 as a current collector.

5. The secondary battery according to claim 4, Wherein, The secondary battery includes a battery element formed by alternately laminating the current collector and an electrode element, The electrode element includes: A positive electrode active material layer; A negative electrode active material layer; A separator disposed between the positive electrode active material layer and the negative electrode active material layer; A first electrolyte layer interposed between the positive electrode active material layer and the separator; and A second electrolyte layer interposed between the negative electrode active material layer and the separator.

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