JP2011233564A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery having reduced internal resistance.SOLUTION: A battery has a positive electrode 7, a negative electrode 8 opposing the positive electrode 7, and an electrolyte 9 which is in contact with the positive electrode 7 and the negative electrode 8. At least one of the positive electrode 7 and the negative electrode 8 is provided with a conductive base substrate 1 having conductivity, an active material layer 2 which is laminated on the conductive base substrate 1 and contains a carbon material as a base material, and a carbon coating 3 which is interposed between the conductive base substrate 1 and the active material layer 2 and is smaller in thickness than the conductive base substrate 1 and the active material layer 2.

Description

  The present invention relates to a battery using a carbon material as an active material. The battery includes a physical battery such as a capacitor, and a chemical battery such as a primary battery and a secondary battery.

  Patent Document 1 discloses a technique for reducing internal resistance by adding a non-insulating binder containing a conductive polymer having polystyrene sulfonic acid to activated carbon powder. Patent document 2 uses the 1st activated carbon with an average particle diameter of 1 micrometer or less and the 2nd activated carbon with an average particle diameter of 1 micrometer or more together, raises the contact frequency between activated carbon particles, and reduces resistance inside an electrode. Disclosed is a technique for reducing.

Japanese Patent Laid-Open No. 8-1007048 JP 2009-130066 A

  According to the technique described above, it is not always sufficient to reduce the interface resistance between the conductive substrate and the active material layer. The present invention has been made in view of the above circumstances, and can reduce the interfacial resistance between a conductive substrate based on a conductive material and an active material layer based on a carbon material. It is an object of the present invention to provide a battery that can reduce the battery.

  The battery according to the present invention includes a positive electrode, a negative electrode facing the positive electrode, and an electrolyte in contact with the positive electrode and the negative electrode, and at least one of the positive electrode and the negative electrode includes a conductive base having conductivity, a conductive It has an active material layer based on a carbon material laminated on a substrate, and a carbon film that is interposed between the conductive substrate and the active material layer and is thinner than the conductive substrate and the active material layer.

  A conductive carbon film having a smaller thickness than the conductive substrate and the active material layer is interposed between the conductive substrate and the active material layer. For this reason, the interface resistance between the conductive substrate and the active material layer can be reduced. As a result, the internal resistance of the battery can be reduced.

It is sectional drawing which concerns on Example 1 and shows the concept of the electrode which forms a positive electrode and a negative electrode in a cross section. It is sectional drawing which concerns on Example 2 and shows the concept of the electrode which forms a positive electrode and a negative electrode in a cross section. It is a figure which shows the concept of the measuring apparatus which measures the resistance of the electrode which forms a positive electrode and a negative electrode. 12 is a cross-sectional view of a capacitor according to Application Example 1. FIG. 12 is a cross-sectional view of a capacitor according to Application Example 2. FIG.

  The battery includes a positive electrode, a negative electrode facing the positive electrode, and an electrolyte in contact with the positive electrode and the negative electrode. Examples of the battery include a physical battery such as a capacitor, and a chemical battery such as a primary battery and a secondary battery. Examples of the electrolyte include an aqueous electrolyte, a non-aqueous electrolyte, and a solid polymer. Preferred examples of the solvent for the non-aqueous electrolyte include the following as the solvent for the non-aqueous electrolyte. These solvents may be used alone or in combination of two or more. Propylene carbonate, propylene carbonate derivative, ethylene carbonate, ethylene carbonate derivative, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, 1,3-dioxolane, dimethyl sulfoxide, sulfolane, formamide, dimethylformamide, dimethylacetamide, Dioxolane, phosphoric acid triester, maleic anhydride, succinic anhydride, phthalic anhydride, 1,3-propane sultone, 4,5-dihydropyran derivative, nitrobenzene, 1,3-dioxane, 1,4-dioxane, 3- Methyl-2-oxazolidinone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydrofuran derivative, sydnone Things, acetonitrile, nitromethane, alkoxy ethane, toluene.

  It is preferable that the separator which suppresses the short circuit of a positive electrode and a negative electrode is provided between the positive electrode and the negative electrode. The separator can be formed of a nonwoven fabric, a woven fabric, or the like, but may be anything as long as it suppresses a short circuit between the positive electrode and the negative electrode.

  At least one of the positive electrode and the negative electrode is interposed between the conductive base having conductivity, the active material layer based on the carbon material laminated on the conductive base, the conductive base and the active material layer, and conductive. A carbon film having a thickness smaller than that of the substrate and the active material layer. A carbon film means a film formed of carbon atoms. The carbon film can be formed by a CVD process. In this case, as the carbon source, hydrocarbon gas or alcohol such as methanol, ethanol or butanol can be employed. Examples of the hydrocarbon gas include methane gas, ethane gas, acetylene gas, propane gas, and butane gas. Examples of the material of the conductive substrate include titanium, titanium alloy, copper, copper alloy, iron, iron alloy (including stainless steel), aluminum, and aluminum alloy. The lower limit of the substrate temperature in the CVD (chemical vapor deposition) process includes 400 ° C., 500 ° C., and 600 ° C., although it varies depending on the carbon source, the substrate, and the required properties of the carbon film. Examples of the upper limit value of the substrate temperature in the CVD process include 600 ° C., 700 ° C., 800 ° C., and 1000 ° C.

  If necessary, a catalyst layer having a seed catalyst can be provided at the boundary between the carbon film and the conductive substrate. In this case, the carbon film is modified. A transition metal is illustrated as a seed catalyst. In particular, V-VIII group metals are exemplified. Although it differs depending on the degree of modification of the carbon film, the seed catalyst may be iron alone, but an AB-based alloy is exemplified, and an AB-based iron alloy is exemplified. Here, A is at least one of iron, cobalt, and nickel, and B is at least one of titanium, vanadium, zirconium, niobium, hafnium, and tantalum. In this case, it is preferable to include at least one of an iron-titanium alloy and an iron-vanadium alloy. Furthermore, a cobalt-titanium alloy, a cobalt-vanadium alloy, a nickel-titanium alloy, a nickel-vanadium alloy, an iron-zirconium alloy, and an iron-niobium alloy can be used. In the case of an iron-titanium alloy, the composition is such that titanium is 10% or more, 20% or more, 30% or more, and the balance is iron in terms of mass ratio. In the case of an iron-vanadium alloy, a composition in which vanadium is 10% or more, 20% or more, 30% or more and the balance is iron is exemplified by mass ratio.

  The active material layer is based on a carbon material. Examples of the carbon material include at least one of activated carbon and graphite. Examples of the activated carbon include coconut shell activated carbon, petroleum coke activated carbon, biological activated carbon and the like. The activated carbon activation treatment method may be a known activation method such as a steam activation treatment method or a molten KOH activation treatment method. The activated carbon may be powdered activated carbon or granular activated carbon. The average particle diameter and specific surface area of the activated carbon are not particularly limited, and can be appropriately selected as necessary. In addition to carbon materials such as activated carbon and graphite, a conductive agent, a binder, and the like can be blended in the active material layer as necessary. Examples of the conductive agent include carbon black such as ketjen black, acetylene black, and furnace black, natural graphite, artificial graphite, metal fiber, titanium oxide, and ruthenium oxide.

  Conventionally, an active material layer based on a carbon material is deposited on the surface of a metal conductive substrate to form an electrode. However, since an oxide film with high insulating properties is usually formed on the surface of the metal conductive substrate, and the active material layer deposited and the surface of the metal conductive substrate are electrically connected only by contact, the active material The interface resistance between the layer and the surface of the metal conductive substrate becomes very large, which causes IR loss when a current flows. Further, in the operating environment, the metal conductive substrate may be ionized, and the metal ions may be mixed into the electrolytic solution and the electrode, thereby causing deterioration in battery performance. Therefore, by removing the oxide film on the surface of the metal conductive substrate, by depositing carbon atoms and forming a carbon film, the formation of the oxide film on the surface of the metal conductive substrate is suppressed, and the affinity with the active material layer As a result of the improvement, not only the interface resistance is reduced, but also the elution of metal ions from the metal conductive substrate is suppressed, and the durability of the battery can be expected to be improved. The carbon film is excellent in electrical conductivity and stable in the operating environment, and even if it is oxidized, it does not become a cation and can reduce the risk of battery performance deterioration.

Example 1
Embodiment 1 of the present invention will be described below with reference to FIG. 1 showing a conceptual diagram. According to this example, a titanium plate was used as the substrate 1 constituting the conductive substrate. The substrate 1 is mirror-polished and has a predetermined size (0.5 mm × 10 mm × 10 mm). A catalyst layer 4 formed of an iron alloy-based seed catalyst (Fe—Ti alloy, Fe is 80% by mass, and Ti is 20%) was provided on the entire surface including the surface 1 a of the substrate 1. In this case, a coating liquid was prepared in which iron alloy (iron-titanium alloy) particles were dispersed as seed catalyst particles (particle size: 1 to 6 nanometers) in dehydrated hexane. And the density | concentration of the coating liquid was prepared so that a light absorbency (Abs.) Might be 0.3 on the measurement conditions of wavelength 680 nanomail with the visible photometer (WPA company make: CO7500). The alloy ratio of the iron-titanium alloy particles in the coating solution was iron: titanium = 80: 20 by mass ratio. Thus, in the seed catalyst particles, the mass% of iron is higher than the mass% of titanium. After immersing the substrate 1 in this coating solution for a predetermined time (30 minutes), the substrate 1 was pulled up into the coating solution and allowed to dry naturally. Thus, the catalyst layer 4 formed of a thin film of iron-titanium alloy was used as a seed catalyst to form the entire surface including the surface 1a of the substrate 1.

  Thereafter, using the CVD film forming apparatus, first, with the substrate 1 held in the reaction vessel, the reaction vessel was evacuated to adjust the pressure in the reaction vessel to 4 KPa, and held at 620 ° C. for 5 minutes. Thereafter, with the substrate 1 in the reaction vessel heated to 650 ° C., acetylene gas, which is a hydrocarbon-based gas, is flowed into the reaction vessel as a carbon source (flow rate per unit time: 5 liter / min), and acetylene gas In this atmosphere, film formation was performed for 6 minutes. As a result, a carbon film 3 (thickness: 2 μm) was formed on the catalyst layer 4 on the surface 1 a of the substrate 1. The catalyst layer 4 is considered to have a function of modifying the carbon of the carbon film 3.

Thereafter, activated carbon particles having a large number of pores (average particle size: 12 micrometers, specific surface area: 1731 m ² / g, Kureha Co., Ltd., A-BAC PW15 M aluminum tie), binder (polyvinylidene fluoride), conductive agent ( Ketjen Black) was mixed and further mixed with a solvent (N-methyl-2-pyrrolidone, NMP) to form an ink. As a mixture ratio, the mass ratio was activated carbon: binder: conductive agent = 86: 10: 4). Next, an electrode 5 in which a catalyst layer 4 is provided in the substrate 1 and ink is applied to the surface 1a and dried to form an active material layer 2 based on activated carbon that functions as a carbon material on the surface of the substrate 1 is formed. Obtained.

  As shown in FIG. 1, the electrode 5 according to Example 1 can constitute one or both of a positive electrode and a negative electrode of a battery (physical battery or chemical battery). The electrode 5 is interposed between the substrate 1 functioning as a conductive base having conductivity, the active material layer 2 based on activated carbon laminated on the surface 1 a of the substrate 1, and the substrate 1 and the active material layer 2. And carbon film 3 to be used. The carbon film 3 is formed on the entire boundary between the substrate 1 and the active material layer 2. An iron alloy thin film is provided as a catalyst layer 4 at the boundary between the carbon film 3 and the active material layer 2. Accordingly, as shown in FIG. 1, the substrate 1, the catalyst layer 4, the carbon film 3, and the active material layer 2 are laminated in this order. The carbon film 3 is thinner than the substrate 1 and the active material layer 2. Here, the thickness t1 of the substrate 1 was 0.5 millimeters, the thickness t2 of the active material layer 2 was 0.1 millimeters, and the thickness t3 of the carbon coating 3 was 2 micrometers. The thickness of the catalyst layer 4 is considered to be 100 nanometers or less. The electrode 5 can form one or both of a positive electrode and a negative electrode.

As shown in FIG. 3, the electrode 5 is sandwiched between the first resistance measurement jig 61 and the second resistance measurement jig 62 in the thickness direction, and a load (10 kgf / cm ² ) is applied in the thickness direction of the electrode 5 while applying a current ( 3 amps) was passed in the thickness direction of the electrode 5 and the voltage was measured. In this case, the voltage after 1 minute of current application was measured. The resistance value was determined based on the equation R = V / I. The results are shown in Table 1. According to Example 1 in which the carbon film 3 was formed, the resistance value was 2.0 mΩ · cm ² and was extremely small. Thereby, it is considered that the interface resistance between the surface 1a of the substrate 1 and the active material layer 2 is small. Note that the surfaces of the first resistance measuring jig 61 and the second resistance measuring jig 62 are gold-plated.

(Example 2)
The second embodiment basically has the same configuration and the same function and effect as the first embodiment. However, the catalyst layer was not provided on the surface of the substrate 1. According to this example, as in Example 1, a titanium plate was used as the substrate 1 constituting the conductive substrate. The substrate 1 is mirror-polished and has a predetermined size (0.5 mm × 10 mm × 10 mm). No iron-based seed catalyst was provided on the surface 1 a of the substrate 1. Then, in the same manner as in Example 1, with the substrate 1 held in the reaction vessel, the reaction vessel was evacuated to adjust the pressure in the reaction vessel to 4 KPa and held at 620 ° C. for 5 minutes. As a result, the oxide film formed on the surface 1a of the substrate 1 is removed.

  Thereafter, with the substrate 1 in the reaction vessel heated to 650 ° C., acetylene gas, which is a hydrocarbon-based gas, is flowed into the reaction vessel as a carbon source (flow rate per unit time: 5 liter / min), and acetylene gas In this atmosphere, film formation was performed for 6 minutes. As a result, a carbon film 3 (thickness: 2 μm) was formed on the surface 1 a of the substrate 1. Thereafter, activated carbon particles, a binder, and a conductive agent (Ketjen Black) were mixed under the same conditions as in Example 1, and further mixed with a solvent (NMP) to form an ink. Under the same conditions as in Example 1, ink was applied onto the carbon film 3 on the surface 1a of the substrate 1 and dried to form the active material layer 2, whereby an electrode 5 was obtained. As shown in FIG. 2, the electrode 5 according to Example 2 can constitute one or both of a positive electrode and a negative electrode of a battery (physical battery or chemical battery). The electrode 5 is interposed between a substrate 1 (titanium substrate) as a conductive base having conductivity, an active material layer 2 based on activated carbon laminated on the substrate 1, and the substrate 1 and the active material layer 2. And carbon film 3 to be used. The carbon film 3 is formed on the entire boundary between the surface 1 a of the substrate 1 and the active material layer 2. At the boundary between the carbon film 3 and the active material layer 2, an iron alloy thin film catalyst layer is not provided. Therefore, as shown in FIG. 2, the substrate 1, the carbon film 3, and the active material layer 2 are laminated in this order.

The carbon film 3 is thinner than the substrate 1 and the active material layer 2. Here, the thickness t1 of the substrate 1 was 0.5 millimeters, the thickness t2 of the active material layer 2 was 0.1 millimeters, and the thickness t3 of the carbon coating 3 was 2 micrometers. The electrode 5 can form one or both of a positive electrode and a negative electrode. Then, the electrode 5 is sandwiched between the first resistance measurement jig 61 and the second resistance measurement jig 62 under the same conditions as in the first embodiment, and a load is applied in the thickness direction of the electrode 5, while in the thickness direction of the electrode 5. A current (3 amperes) was passed and the voltage was measured. Based on the equation R = V / I, the resistance value in the thickness direction of the electrode 5 was determined. The results are shown in Table 1. According to Example 2 in which the carbon film 3 was formed, the resistance value was 2.3 mΩ · cm ² and was extremely small. Thereby, it is considered that the interface resistance between the surface 1a of the substrate 1 and the active material layer 2 is small.

(Comparative Example 1)
In Comparative Example 1, a substrate 1 and an active material layer 2 are laminated. In Comparative Example 1, the same titanium plate as in Example 1 was used as the substrate 1. The surface of the substrate 1 was not provided with a catalyst layer of an iron-based seed catalyst and a carbon film. Then, under the same conditions as in Example 1, activated carbon particles, a binder, and a conductive agent (Ketjen Black) were mixed, and further mixed with a solvent (NMP) to form an ink. Under the same conditions as in Example 1, ink was applied to the surface of the substrate 1 and dried to form an active material layer 2, whereby an electrode according to Comparative Example 1 was obtained. Then, under the same conditions as in Example 1, this electrode was sandwiched between resistance measuring jigs, a current (3 amperes) was passed while applying a load, and the voltage was measured. The resistance value was determined based on the equation R = V / I. The results are shown in Table 1. According to Comparative Example 1 in which the carbon film 3 was not formed at the interface between the active material layer 2 and the substrate 1, the resistance value was 331.16 mΩ · cm ² . This is 200 times that of Examples 1 and 2 (2.0 mΩ · cm ² , 2.3 mΩ · cm ² ) in which the carbon film 3 is formed at the interface between the active material layer 2 and the substrate 1. It was about and it was quite big. In Comparative Example 1, since the carbon film 3 is not formed at the interface between the active material layer 2 and the substrate 1, it is presumed that the interface resistance between the substrate 1 and the active material layer 2 has increased.

(Comparative Example 2)
In Comparative Example 2, the substrate 1, the catalyst layer 4, and the active material layer 2 are laminated in this order. In Comparative Example 2, the carbon film 3 was not formed on the substrate 1. That is, according to Comparative Example 2, as in Example 1, a titanium substrate was used as the substrate 1. Then, under the same conditions as in Example 1, an iron alloy-based seed catalyst (Fe—Ti alloy, Fe is 80% by mass, Ti is 20%) was provided on the surface of the substrate 1. However, the carbon film 3 was not formed on the substrate 1. Thereafter, under the same conditions as in Example 1, activated carbon particles, a binder, and a conductive agent were mixed, and further mixed with a solvent (NMP) to form an ink. The blending ratio was the same as in Example 1. And ink was apply | coated to the surface in which the iron-type seed catalyst was provided among the board | substrates 1 on the conditions similar to Example 1, it was made to dry and the active material layer 2 was formed, and the electrode was obtained. Under the same conditions as in Example 1, the electrode according to Comparative Example 2 was sandwiched between resistance measurement jigs, and a current (3 amperes) was passed while applying a load, and the voltage was measured. The resistance value was determined based on the equation R = V / I. The results are shown in Table 1. According to Comparative Example 2 in which no carbon film is formed at the interface between the active material layer 2 and the substrate 1, the resistance value is 183.7 mΩ · cm ^2, and at the interface between the active material layer 2 and the substrate 1. It was considerably larger than Examples 1 and 2 (2.0 mΩ · cm ² , 2.3 mΩ · cm ² ) on which the carbon film 3 was formed. Since the carbon film 3 is not formed at the interface between the active material layer 2 and the substrate 1, it is assumed that the interface resistance between the substrate 1 and the active material layer 2 is large.

  As can be seen from Table 1, when the carbon film 3 is laminated at the interface between the substrate 1 and the active material layer 2, it can be seen that the resistance in the thickness direction of the electrode 5 is greatly reduced. It is considered that the decrease in the interface resistance between the surface 1a of the substrate 1 and the carbon film 3 contributes. When Example 1 and Example 2 are compared, even when the substrate 1, the carbon film 3, and the active material layer 2 are laminated, the seed catalyst catalyst layer 4 is formed on the surface 1a of the substrate 1 and the carbon film. It can be seen that the resistance value is lowered by about 13% ((2.3-2.0) /2.3≈0.13) even if it is provided between the two. It is considered that the decrease in the interface resistance between the surface 1a of the substrate 1 and the carbon film 3 contributes.

(Example 3)
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 can be applied mutatis mutandis. Based on another test example performed by the present inventors, a catalyst layer 4 of Fe-V alloy (Fe is 85% in mass ratio, V15%) as an iron-based seed catalyst on the surface of the substrate 1, Providing prior to the CVD process is also considered beneficial. In this case, the substrate 1 is immersed in a coating solution for a predetermined time (for example, 30 seconds) by a dip coater in the atmosphere. Thereafter, the substrate 1 is pulled up from the coating solution at room temperature in an air atmosphere, and the hexane of the substrate 1 is dried by natural drying in a state where the coating solution adheres to the surface of the substrate 1. Thus, it is preferable to form an iron-vanadium alloy thin film (thickness: for example, 5 to 100 nanometers) and thereby form the catalyst layer 4. Here, the coating liquid can be formed by dispersing iron-vanadium alloy particles in hexane. The iron-vanadium alloy particles can be made 85% iron and 15% vanadium by mass ratio, and the iron content is preferably larger than the vanadium content. About a coating liquid, a density | concentration can be adjusted so that a light absorbency may be 0.3 on the measurement conditions of wavelength 680 nanometer with a visible photometer (WPA company make: CO7500). Thereafter, as in Examples 1 and 2, it is preferable to form the carbon film 3 on the catalyst layer 4 formed of a thin film of the iron-based seed catalyst in the substrate 1.

  As shown in FIG. 1, the electrode according to the present embodiment includes a substrate 1 as a conductive base having conductivity, an active material layer 2 based on activated carbon laminated on the substrate 1, a substrate 1 and an active material. And a carbon film 3 interposed between the layer 2 and the layer 2. The carbon film 3 is formed on the entire boundary between the substrate 1 and the active material layer 2. A catalyst layer 4 formed of an iron alloy thin film is provided at the boundary between the carbon film 3 and the active material layer 2. In addition, it is preferable that the thickness of the catalyst layer 4 is 100 nanometers or less.

Example 4
Since this embodiment basically has the same configuration and the same function and effect as those of the first embodiment, FIG. 1 can be applied mutatis mutandis. Based on another test example conducted by the present inventors, it is considered beneficial to form a seed catalyst of simple iron on the surface of the substrate 1 by sputtering. Therefore, the catalyst layer 4 formed of a thin film of simple iron is formed on the surface 1a of the substrate 1 by sputtering using argon gas. Thereafter, using a CVD film forming apparatus under the same conditions as in Example 1, the substrate 1 held in the reaction vessel is heated to 650 ° C., and acetylene gas is allowed to flow into the reaction vessel as a carbon source, thereby acetylene gas. The film formation process is performed in the atmosphere. Thereby, the carbon film 3 is formed on the catalyst layer 4 on the surface 1 a of the substrate 1. Further, activated carbon particles having a large number of pores, a binder, and a conductive agent are mixed under the same conditions as in Example 1, and further mixed with a solvent to form an ink. Furthermore, ink is applied on the carbon film 3 of the substrate 1 and dried to obtain an electrode 5 in which an active material layer 2 based on activated carbon is formed on the surface of the substrate 1.

  As shown in FIG. 1, an electrode 5 according to this embodiment includes a conductive substrate 1, an active material layer 2 based on activated carbon laminated on a surface 1 a of the substrate 1, a substrate 1, and an active material. And a carbon film 3 interposed between the layer 2 and the layer 2. An iron alloy thin film is provided as a catalyst layer 4 at the boundary between the carbon film 3 and the active material layer 2. The thickness of the carbon film 3 is thinner than the thickness of the substrate 1 and the active material layer 2.

(Example 5)
Since the present embodiment basically has the same configuration and the same operation and effect as the first and second embodiments, FIGS. 1 and 2 can be applied mutatis mutandis. Based on another test example carried out by the present inventors, stainless steel (for example, SUS304 series) may be employed as the substrate 1 instead of titanium alone. Therefore, as shown in FIGS. 1 and 2, the electrode according to this example includes a substrate 1 as a conductive base having conductivity, an active material layer 2 based on activated carbon laminated on the substrate 1, and It has a carbon film 3 interposed between the substrate 1 and the active material layer 2. The carbon film 3 is formed on the entire boundary between the substrate 1 and the active material layer 2.

  As shown in FIG. 1, a thin film of iron alone or an iron alloy (Fe—Ti, Fe—V, etc.) may be provided as a catalyst layer 4 at the boundary between the carbon film 3 and the active material layer 2. In some cases, as shown in FIG. 2, an iron alloy thin film may not be provided as a catalyst layer 4 at the boundary between the carbon film 3 and the active material layer 2.

(Example 6)
Since the present embodiment basically has the same configuration and the same operation and effect as the first and second embodiments, FIGS. 1 and 2 can be applied mutatis mutandis. Referring to another test example carried out by the present inventors, copper having high conductivity can be adopted as the substrate 1 instead of a single titanium plate. Accordingly, as shown in FIGS. 1 and 2, the electrode according to this example includes a conductive substrate 1, an active material layer 2 based on activated carbon laminated on the surface 1 a of the substrate 1, and a substrate 1 and an active material layer 2. The carbon film 3 is formed on the entire boundary between the substrate 1 and the active material layer 2. As shown in FIG. 1, a thin film of an iron simple substance or an iron alloy (Fe—Ti, Fe—V, etc.) iron alloy may be provided as a catalyst layer 4 at the boundary between the carbon film 3 and the active material layer 2. . In some cases, an iron alloy thin film may not be provided as a catalyst layer 4 at the boundary between the carbon film 3 and the active material layer 2 as shown in FIG.

(Test example)
The resistance value was actually obtained when the substrate having a predetermined thickness (50 μm) was titanium, stainless steel (SUS304), or copper. Even if the material is different from titanium, stainless steel, etc., the size of the substrate is the same. In this test example, although a catalyst layer and an active material layer were not formed on the substrate, a CVD process for forming a carbon film was performed. In this case, the substrate temperature was changed to 750 ° C., 500 ° C., and 410 ° C., and CVD treatment was performed to form a carbon film on the surface of the substrate. In this case, the resistance value was measured under the same conditions as in Example 1. The measurement results are shown in Table 2.

  As can be understood from Table 2, when the carbon film is formed on the substrate by performing the CVD process as compared with the case where only the substrate is measured, even if the substrate temperature in the CVD process is as low as 410 ° C. The resistance was reduced. It is estimated that the interface resistance was reduced because the carbon film was formed. When the material of the substrate 1 was titanium or SUS, the resistance was better than that of the substrate alone even when the substrate temperature in the CVD process was as low as 410 ° C. When the substrate temperature in the CVD process was raised to 500 ° C. and 750 ° C., the resistance was low and good. Therefore, in order to reduce the interface resistance, the substrate temperature in the CVD process is preferably 500 ° C. or higher.

(Application example 1)
FIG. 4 is a conceptual diagram of Application Example 1. As shown in FIG. 4, the capacitor that functions as a physical battery includes a positive electrode 7, a negative electrode 8 that faces the positive electrode 7, an electrolyte 9 (electrolytic solution) that contacts the positive electrode 7 and the negative electrode 8, and a positive electrode 7 and a negative electrode 8. And a separator 6 having an electrical insulating property for partitioning so as not to be short-circuited. A seal member 62 that prevents leakage of the electrolyte 9 is provided. The positive electrode 7 is interposed between the conductive substrate 100 also serving as a container, the active material layer 2 based on activated carbon laminated on the conductive substrate 100, and the conductive substrate 100 and the active material layer 2. And a carbon film 3 having a thickness smaller than that of the active material layer 2.

  The negative electrode 8 is interposed between the conductive substrate 101 which also serves as a container, the active material layer 2 based on activated carbon laminated on the conductive substrate 101, the conductive substrate 101 and the active material layer 2, and the conductive substrate 101 and The carbon film 3 is thinner than the active material layer 2. The carbon film 3 is formed by the above-described CVD process. A catalyst layer 4 can be provided between the carbon film 3 and the conductive substrate 100 as necessary.

(Application example 2)
FIG. 5 is a conceptual diagram of Application Example 2. As shown in FIG. 5, the capacitor that functions as a physical battery includes a positive electrode 7, a negative electrode 8 that faces the positive electrode 7, an electrolyte 9 (electrolytic solution) that contacts the positive electrode 7 and the negative electrode 8, and a positive electrode 7 and a negative electrode 8. And a separator 6 for partitioning so as not to be short-circuited. The positive electrode 7 is interposed between the conductive substrate 100 also serving as a container, the active material layer 2 based on activated carbon laminated on the conductive substrate 100, the conductive substrate 100 and the active material layer 2, and the conductive substrate 100 and The carbon film 3 is thinner than the active material layer 2. The negative electrode 8 is interposed between the conductive substrate 101 serving also as a container, the active material layer 2W based on graphite laminated on the conductive substrate 101, and the conductive substrate 101 and the active material layer 2W. A carbon film 3W having a thickness smaller than that of the active material layer 2W. The catalyst layer 4 can be provided between the carbon film 3 and the conductive substrate 100 or between the carbon film 3W and the conductive substrate 101 as necessary. The carbon film 3 is formed by the above-described CVD process. Note that the graphite material constituting the active material layer 2W of the negative electrode 8 is doped with lithium ions and / or metallic lithium, which lowers the potential of the negative electrode 8 and increases the operating voltage of the capacitor. Therefore, the capacitor is a lithium ion capacitor.

(About the interface resistance reduction mechanism)
As a mechanism that can reduce the interfacial resistance, the oxide film that can be placed on the surface of a substrate such as a substrate is removed, and then a carbon film with excellent conductivity is joined, and the carbon film and the active material layer are in contact with each other. Conceivable. Although it is not necessarily clear at this stage as a carbon film, it is presumed to be a carbon nanotube (CNT) or graphite. In this case, although there is a gap between the CNTs, even if a substrate such as a substrate in the gap is oxidized, a current flows through the substrate- (catalyst particles) -CNT-active material layer. It is thought to be reduced. The same applies when the graphite is porous. Rather, it is considered that the porous material can increase the bonding strength of the active material layer and reduce the electric resistance because the contact area with the carbon film is large. In addition, as one of the characteristics required for the carbon film, there is a bonding strength (adhesion strength) with the substrate. In the case of a battery using an electrolytic solution, resistance to the electrolytic solution is required. Here, the carbon that forms the carbon film is basically excellent in chemical resistance, and therefore is excellent in resistance to electrolyte.

  (Others) Examples of the carbon film forming method include CVD (chemical vapor deposition) such as thermal CVD and plasma CVD, PVD (physical vapor deposition) such as vacuum deposition, sputtering, ion plating, and ion beam deposition. The battery includes a physical battery such as a capacitor, and a chemical battery such as a primary battery and a secondary battery.

From the above description, the following technical idea can also be grasped.
[Additional Item 1] In a method of manufacturing a battery comprising a positive electrode, a negative electrode facing the positive electrode, and the electrolyte in contact with the positive electrode and the negative electrode, at least one of the positive electrode and the negative electrode is electrically conductive. A conductive substrate preparation step for preparing a conductive substrate, a carbon film formation step for forming a carbon coating on one surface of the conductive substrate by CDV treatment, and an active material layer based on a carbon material on the carbon coating. A method for producing a battery, characterized by being produced by an active material layer forming step to be formed.
[Additional Item 2] In Additional Item 1, a seed catalyst application step of applying a seed catalyst to form the carbon film on at least one surface of the conductive substrate is provided before the conductive substrate preparation step. A battery manufacturing method characterized by the above. As a coating method, a known method can be adopted.

  1 is a substrate (conductive substrate), 2 is an active material layer, 3 is a carbon film, 4 is a catalyst layer, 7 is a positive electrode, 8 is a negative electrode, 9 is an electrolyte, and 100 is a conductive substrate.

Claims (4)

  A positive electrode; a negative electrode facing the positive electrode; and the positive electrode and an electrolyte in contact with the negative electrode, wherein at least one of the positive electrode and the negative electrode has conductivity. The conductive substrate A battery having an active material layer based on a carbon material laminated on the substrate, and a carbon film interposed between the conductive substrate and the active material layer and thinner than the conductive substrate and the active material layer .   2. The battery according to claim 1, wherein the conductive substrate is one of titanium, titanium alloy, copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy.   3. The battery according to claim 1, wherein a catalyst layer having a seed catalyst is provided at a boundary between the conductive substrate and the carbon film.   4. The battery according to claim 1, wherein the carbon film is a CVD carbon film formed by a CDV process.

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