JP6760034B2 - Conductive composition, current collector with base layer for power storage device, electrode for power storage device, and power storage device - Google Patents

Description

The present invention relates to a conductive composition, an electrode for a power storage device obtained by using the composition, and a power storage device obtained by using the electrode. More specifically, the present invention relates to a conductive composition having a function of increasing the internal resistance of the power storage device when the temperature of the power storage device rises, an electrode for the power storage device, and a power storage device.

In recent years, small portable electronic devices such as digital cameras and mobile phones have come into widespread use. It has always been required to minimize the volume and weight of these electronic devices, and it is also required to realize a compact, lightweight and large-capacity battery for the mounted battery. In particular, lithium-ion secondary batteries have a higher energy density than water-based secondary batteries such as lead-acid batteries, Nikkado batteries, and nickel-hydrogen batteries, and are therefore becoming more important as power sources for personal computers and mobile terminals. Furthermore, it is expected to be preferably used as a high-output power source for mounting on vehicles.

Lithium-ion secondary batteries have the advantage of high energy density, but because they use non-aqueous electrolytes, sufficient safety measures are required. In recent years, as the size and capacity of batteries have increased, ensuring safety has become a major issue. In particular, when the battery temperature rises abnormally and rapidly due to a short circuit inside the battery, it becomes difficult to regulate heat generation only by the safety mechanism provided outside the battery, and there is a risk of ignition. is there.

Patent Document 1 describes a method of joining an electron conductive material having a function of a resistance temperature coefficient resistor (hereinafter referred to as PTC) to a current collector. However, since the thickness of the electron conductive material is as thick as 50 μm, there is a problem that the energy density of the battery as a whole is lowered.

Patent Document 2 discloses that any one of the positive electrode, the negative electrode, and the non-aqueous electrolytic solution has the characteristics of PTC. However, in order to impart PTC characteristics to these, it is necessary to add a large amount of additives that do not contribute to the battery capacity, resulting in a decrease in energy density.

Patent Document 3 describes a method of providing a conductive layer made of a crystalline thermoplastic resin, a conductive agent, and a binder on the surface of a current collector. When the temperature inside the battery exceeds the melting point of the crystalline thermoplastic resin, the resistance of the conductive layer increases and the current between the current collector and the active material is cut off. However, there is a problem that the internal resistance of the battery during normal operation becomes high and the output characteristics of the battery deteriorate.

Patent Document 4 describes a method in which a conductive layer made of polyvinylidene fluoride and a conductive agent is provided on the surface of a current collector, and the current collector provided with the conductive layer is heated at a temperature exceeding 120 ° C. However, in addition to the addition of a heat treatment step, there is a problem that the resistance rise is not sufficient when the temperature inside the battery rises.

Patent Document 5 describes a method of providing a current collector provided with a conductive layer composed of agglomerates of polyolefin-based emulsion particles using a high molecular weight flocculant and / or a low molecular weight coagulant and a conductive material. However, it is difficult to control the agglomeration diameter of emulsion particles by using a coagulant composed of a polymer or a low molecule, and the effect is not sufficient. Further, since the surface of the conductive material is covered with a non-conductive polyolefin-based resin, there is a problem that the internal resistance of the battery during normal operation increases and the output characteristics of the battery deteriorate.

Japanese Unexamined Patent Publication No. 10-241665 Japanese Unexamined Patent Publication No. 11-329503 Japanese Unexamined Patent Publication No. 2001-357854 Japanese Unexamined Patent Publication No. 2012-104422 International Publication No. 2014/157405

An object of the present invention is a power storage device (for example, a power storage device having a function of increasing the internal resistance when the internal temperature of the power storage device rises, which is excellent in the output characteristics of the power storage device because of its excellent conductivity during normal operation (for example). A conductive composition for forming a non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery), an electric double layer capacitor, a lithium ion capacitor, etc., which is excellent in conductivity and safety function of a power storage device. To provide a composition.

The present invention is a conductive composition containing a conductive carbon material (A), water-dispersed olefin resin fine particles (B), a polyvalent metal compound (C), and an aqueous liquid medium (D). When the device generates heat, the resistance of the current collector increases and the current is cut off, thereby avoiding ignition of the power storage device.
Further, the presence of the polyvalent metal compound (C) in the conductive composition breaks the contact between the conductive carbon materials due to the volume expansion of the water-dispersed olefin-based resin fine particles that occurs when the power storage device generates heat. It was found that the effect was enhanced, and the present invention was reached. In the present invention, since the resin fine particles are aggregated using the metal ions of the polyvalent metal compound (C), the aggregated particle size can be controlled relatively easily, and the particles are aggregated by changing the valence of the metal ions. The shape can be changed, and the agglomerated particles can be controlled relatively easily.
Further, since the resin that increases the internal resistance during heat generation is water-dispersed olefin-based resin fine particles, the conductivity of the carbon material (A) is not impaired, the internal resistance during normal operation can be reduced, and the output characteristics and repetition can be achieved. The cycle characteristics can be improved.

From the above effects, it was found that the output characteristics and the repeated charge / discharge cycle characteristics can be improved during normal operation, and the safety of the power storage device in the event of an internal short circuit or overcharging can be dramatically improved.

That is, the present invention contains a conductive carbon material (A), water-dispersed olefin resin fine particles (B), a water-soluble polyvalent metal compound (C), and an aqueous liquid medium (D), and contains water. Mass ratio (C') / (B') of the solid content mass (B') of the dispersed olefin resin fine particles (B) to the mass (C') of the metal ion in the water-soluble polyvalent metal compound (C) The present invention relates to a conductive composition, which comprises 0.001 to 0.1% by mass.
Further, the content of the conductive carbon material (A) in the solid content of the conductive composition is 10 to 50% by mass, and the content of the water-dispersed olefin resin fine particles (B) is 20 to 60% by mass. The present invention relates to the conductive composition.
The present invention also relates to the conductive composition, which comprises water-dispersed agglomerated fine particles composed of water-dispersed olefin resin fine particles (B) and a water-soluble polyvalent metal compound (C).
Further, the volume average particle diameter (BV1) of the water-dispersed olefin-based resin fine particles (B) is 0.05 to 1 μm, and the above (BV1), the water-dispersed olefin-based resin fine particles (B), and the water-soluble polyvalent metal The present invention relates to the conductive composition characterized in that the ratio of the water-dispersed agglomerated fine particles composed of the compound (C) to the volume average particle diameter (BV2) is BV2 / BV1 of 1.1 to 5.0.
Further, the present invention relates to the conductive composition, which further comprises 10 to 50% by mass of the water-soluble resin (E).
The present invention also relates to the conductive composition, wherein the water-dispersed olefin resin fine particles (B) are modified with at least a carboxylic acid or a carboxylic acid ester.
The present invention also relates to the conductive composition, which is used for forming a base layer of an electrode for a power storage device.
Further, the water-dispersed olefin-based resin fine particles (B) are mixed in a slurry in which the conductive carbon material (A), the water-soluble resin (E), the aqueous liquid medium (D), and the water-soluble polyvalent metal compound (C) are dispersed. ) Is added to the method for producing the conductive composition.
A slurry in which a conductive carbon material (A), a water-soluble resin (E), and an aqueous liquid medium (D) are dispersed is mixed with water-dispersed olefin resin fine particles (B) and a water-soluble polyvalent metal compound (C). The present invention relates to a method for producing the conductive composition.
The present invention also relates to a current collector with a base layer for a power storage device having a current collector and a base layer formed from the conductive composition.
The present invention also relates to an electrode for a power storage device having a current collector, a base layer formed from the conductive composition, and a composite material layer formed from an electrode-forming composition containing an electrode active material and a binder.
The present invention relates to a power storage device including a positive electrode, a negative electrode, and an electrolytic solution, wherein at least one of the positive electrode and the negative electrode is an electrode for the power storage device.

By containing the conductive carbon material (A), the water-dispersed olefin resin fine particles (B), the water-soluble polyvalent metal compound (C), and the aqueous liquid medium (D), the conductivity of the carbon material can be improved. It is possible to provide a power storage device having a function of increasing the internal resistance when the internal temperature of the power storage device rises without damage.

<Conductive composition>
As described above, the conductive composition of the present invention can be used for forming a base layer of a power storage device. The conductive composition contains a conductive carbon material (A), water-dispersed olefin-based resin fine particles (B), a water-soluble polyvalent metal compound (C), and an aqueous liquid medium (D). When dispersing the conductive carbon material (A) in the conductive composition, it is preferable to use a surfactant from the viewpoint of the solid content of the conductive composition, and the inside of the power storage device during electrolytic solution resistance and heat generation. It is more preferable to use the water-soluble resin (E) from the viewpoint of increasing resistance.

The mass ratio (C') / (B') of the solid content mass (B') of the water-dispersed olefin resin fine particles (B) to the mass (C') of the metal ion in the water-soluble polyvalent metal compound is heat generation. From the viewpoint of increasing the internal resistance of the power storage device and the stability of the water-dispersed olefin resin fine particles, it is preferably 0.001 to 0.1% by mass, more preferably 0.002 to 0.03% by mass. ..

The content of the conductive carbon material (A) in the total solid content of 100% by mass of the conductive composition is preferably 10 to 50% by mass, more preferably 15 from the viewpoint of conductivity and internal resistance. ~ 45% by mass.

The content of the water-dispersed olefin resin fine particles (B) in the total solid content of the conductive composition is preferably 100% by mass from the viewpoint of internal resistance and conductivity, and an increase in internal resistance of the power storage device during heat generation. It is 20 to 60% by mass, more preferably 30 to 60% by mass.

The content of the water-soluble resin (E) in the total solid content of 100% by mass of the conductive composition is determined from the viewpoints of electrode adhesion and conductivity, electrolytic solution resistance, and increase in internal resistance of the power storage device during heat generation. Therefore, it is preferably 10 to 50% by mass, more preferably 15 to 45% by mass, and further preferably 20 to 40% by mass.

The total amount of the conductive carbon material (A), the water-dispersed olefin-based resin fine particles (B), and the water-soluble resin (E) in the total solid content of the conductive composition of 100% by mass is the internal resistance, conductivity, and heat generation. From the viewpoint of increasing the internal resistance of the power storage device at the time, it is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more. Any component may be added to the above composition as needed.

The optional component is not particularly limited, but for example, a material that adsorbs or consumes an acid generated by the reaction of an electrolytic solution, a material that generates a gas when the temperature exceeds a predetermined temperature, an inorganic PTC material, and polyolefin-based resin fine particles expand in volume. A material or the like that holds the conductive path after the process may be added.

Examples of the material that adsorbs the acid generated by the reaction of the electrolytic solution include magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), boron oxide (B ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), and the like. Examples thereof include indium oxide (In ₂ O ₃ ).

Materials that consume the acid produced by the reaction of the electrolytic solution include metal carbonates such as magnesium carbonate and calcium carbonate, sodium carboxylate, potassium carboxylate, sodium sulfonate, potassium sulfonate, sodium benzoate, potassium benzoate, etc. Examples thereof include metal organic salts of the above, silicates such as sodium silicate, potassium silicate, aluminum silicate, magnesium silicate and silicon dioxide, and alkaline hydroxides such as magnesium hydroxide.

Examples of the material that generates gas when the temperature exceeds a predetermined temperature include carbonates such as lithium carbonate, zinc carbonate, lead carbonate, and strontium carbonate, and expanded graphite.

Examples of the inorganic PTC material include BaTiMO ₂ (M is one or more elements of Cr, Pb, Ca, Sr, Ce, Mn, La, Y, Nb and Nd).

Examples of the material that retains the conductive path after the polyolefin-based resin fine particles have expanded in volume include cellulose nanofibers, silica, and inorganic fine particles such as alumina.

The appropriate viscosity of the conductive composition depends on the coating method of the conductive composition, but is generally preferably 10 mPa · s or more and 30,000 mPa · s or less.

<Conductive carbon material (A)>
The conductive carbon material (A) in the present invention is not particularly limited as long as it is a conductive carbon material, but graphite, carbon black, and conductive carbon fibers (carbon nanotubes, carbon nanofibers, carbon). Fiber), fullerene, etc. can be used alone or in combination of two or more. The use of carbon black is preferable in terms of conductivity, availability, and cost.

Carbon black includes furnace black, which is produced by continuously pyrolyzing a gas or liquid raw material in a reactor, especially acetylene black, which is made from ethylene heavy oil, and the raw material gas is burned to burn the flame to the bottom of the channel steel. Various types such as channel black that has been rapidly cooled and precipitated, thermal black that is obtained by periodically repeating combustion and thermal decomposition using gas as a raw material, and acetylene black that uses acetylene gas as a raw material, alone or 2 More than one type can be used together. In addition, normally oxidized carbon black, hollow carbon, and the like can also be used.

The oxidation treatment of carbon black involves treating carbon black at a high temperature in the air or secondarily treating it with nitric acid, nitrogen dioxide, ozone, etc., for example, by treating carbon black with a phenol group, a quinone group, a carboxyl group, a carbonyl group, etc. It is a process of directly introducing (covalently bonding) such an oxygen-containing polar functional group to the carbon surface, and is generally performed in order to improve the dispersibility of carbon black. However, since the conductivity of carbon black generally decreases as the amount of functional groups introduced increases, it is preferable to use carbon black that has not been oxidized.

As the specific surface area of carbon black used in the present invention increases, the contact points between the carbon black particles increase, which is advantageous in reducing the internal resistance of the electrode. Specifically, from the viewpoint of conductivity and availability, the specific surface area (BET) obtained from the amount of nitrogen adsorbed is preferably 20 to 1500 m ² / g, more preferably 40 to 1500 m ² / g. It is desirable to use one. The particle size of the carbon black used is preferably 0.005 to 1 μm in terms of primary particle size, and particularly preferably 0.01 to 0.2 μm. However, the primary particle size referred to here is an average of the particle size measured by an electron microscope or the like.

The volume average particle diameter (D50) of the conductive carbon material (A) in the conductive composition is 0 from the viewpoint of difficulty in preparing the composition, variation in the material distribution of the coating film, and variation in the resistance distribution of the electrodes. It is desirable to miniaturize to .03 μm or more and 5 μm or less.

The volume average particle size (D50) referred to here is a particle size that becomes 50% when the volume ratio of the particles is integrated from the fine particle size distribution in the volume particle size distribution, and is generally used. It is measured with a standard particle size distribution meter, for example, a laser scattering type particle size distribution meter (“Microtrack MT3300EXII” manufactured by Nikkiso Co., Ltd.) or the like. The volume average particle size can be measured by the laser scattering method as follows. A slurry in which a conductive carbon material (A) and a water-soluble resin (E) are mechanically dispersed is diluted 100 to 1000 times with water depending on the solid content. Inject the diluted slurry into the cell of the measuring device [Nikkiso Co., Ltd. Microtrack MT3300EXII] until the concentration becomes appropriate in sampling loading, input the refractive index condition of the solvent (water in the present invention) according to the sample, and then measure. I do.

The volume average particle size (D50) of carbon black used in the present invention is preferably larger than the volume average particle size of the water-dispersed olefin resin fine particles (B) from the viewpoint of increasing the internal resistance of the power storage device during heat generation. .. The method for measuring the volume average particle size of the water-dispersed olefin resin fine particles (B) will be described separately.

Examples of commercially available carbon black include Talker Black # 4300, # 4400, # 4500, # 5500 (Tokai Carbon Co., Ltd., Furness Black), Printex L, etc. (Degussa Co., Ltd., Furness Black), Raven7000, 5750, etc. 5250, 5000 ULTRA III, 5000 ULTRA, etc., Conductex SC ULTRA, etc.
, Conductex 975 ULTRA, etc., PUER BLACK 100, 115, 2
05 etc. (Made by Colombian, Furnace Black), # 2350, # 2400B, # 2600B, # 3050B, # 3030B, # 3230B, # 3350B, # 3400B, # 5400B etc. (Made by Mitsubishi Chemical Co., Ltd., Furness Black), MONARCH1400, 1300, 900, Vulcan XC-72R, BlackPearls2000, etc. (Cabot, Furness Black), Ensaco250G, Ensaco260G, Ensaco350G, SuperP-Li (TIMCAL), Ketjen Black EC-300J, EC-600JD (Axo) Examples of graphite such as Denka Black, Denka Black HS-100, FX-35 (manufactured by Denka, acetylene black) and the like include natural graphite such as artificial graphite, scaly graphite, lump graphite and earth graphite. The present invention is not limited to these, and two or more types may be used in combination.

As the conductive carbon fiber, those obtained by firing from a raw material derived from petroleum are preferable, but those obtained by firing from a raw material derived from a plant can also be used. For example, VGCF manufactured by Showa Denko KK, which is manufactured from petroleum-derived raw materials, can be mentioned.

<Water-dispersed olefin resin fine particles (B)>
The water-dispersed olefin-based resin fine particles (B) of the present invention are generally also called an aqueous emulsion, in which the resin particles are dispersed in the form of fine particles without being dissolved in water.

The water-dispersed olefin-based resin fine particles (B) may be combined with two or more types of water-dispersed olefin-based resin fine particles (B), if necessary, and two or more types of water-dispersed resin fine particles other than the olefin-based resin fine particles may be combined. You may. The aqueous dispersion resin fine particles other than the olefin resin fine particles are not particularly limited, but are (meth) acrylic emulsion, nitrile emulsion, urethane emulsion, diene emulsion (SBR (styrene butadiene rubber), etc.), fluorine emulsion (PVDF (PVDF). (Polyvinylidene fluoride), PTFE (polytetrafluoroethylene), etc.) and the like.

The water-dispersed olefin-based resin fine particles are any resin that can expand the volume of the resin in the range of 80 to 180 ° C. and peel off the contact between the conductive carbon materials dispersed in the conductive layer. It is not particularly limited. Examples of the olefin component of the polyolefin resin include ethylene, propylene, isobutylene, isobutene, 1-butene, 2-butene, 1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-hexene, and the like. 1-octene, norbonen and the like can be mentioned. A polymer having a single component of these olefin components or a copolymer having two or more components may be used.

As the water-dispersed olefin resin fine particles, it is preferable that the olefin resin is modified with a carboxylic acid or a carboxylic acid ester. Since the melt resistance of the resin can be imparted by the modification, the volume expansion of the polyolefin resin can be maintained when the internal temperature of the power storage device rises due to an internal short circuit or the like, and the cutting effect between the carbon materials can be maintained. Conceivable. Furthermore, since the water-dispersed olefin-based resin fine particles form an aggregated structure via the polyvalent metal compound (C), the cutting effect between the carbon materials can be further enhanced.

The components of the carboxylic acid or the carboxylic acid ester are not particularly limited, but are acrylic acid, methacrylic acid, maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, fumaric acid, crotonic acid, methyl acrylic acid, and (meth) acrylic acid. Methyl, ethyl (meth) acrylate, propyl (meth) acrylate, butyl acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, (meth) ) Dodecyl acrylate, stearyl (meth) acrylate, vinyl formate, vinyl acetate, vinyl propionate, vinyl pipariate and the like.

As the amount of modification of the above-modified polyolefin resin fine particles, the resin obtained by removing the dispersion medium from the water-dispersed olefin resin fine particles is totally used by a Fourier transform infrared spectroscope (FT-IR: Spectrom One / 100 manufactured by Perkin Elmer). It can be determined by reflection measurement method (ATR) and has a maximum peak height (maximum absorbance) derived from an olefin of 2800 to 3000 cm ^-1 and a maximum peak height (maximum absorbance) derived from a carbonyl of 1690 to 1740 cm ^-1 . It can be calculated from the ratio.

The peak height referred to here is a solid substance obtained by removing the dispersion medium from the water-dispersed olefin resin fine particles (B) and finally drying at 120 ° C., which is measured by FT-IR. For the amount of modification of the polyolefin resin fine particles, a spectrum obtained by plotting the absorbance at wave number was used, and the straight line connecting two points, the point showing the absorbance at 2700 m ^-1 and the point showing the absorbance at 3000 cm ^-1 , was defined as the baseline BX. Of the two or four olefin-derived lines found between 2800 and 3000 cm ^-1 , the height from the maximum peak to the baseline BX (maximum absorbance) (X) and the point indicating the absorbance at 1650 m ^-1 . Height from the maximum peak derived from carbonyl of 1690 to 1740 cm ^-1 to baseline BY (maximum absorbance) (Y) when the straight line connecting two points with the point showing absorbance at 1850 cm ^-1 is defined as baseline BY. It can be obtained from the peak ratio (Y) / (X) of.

As the amount of modification of the resin fine particles, the peak ratio (Y) / (X) is preferably 0.05 to 1.0, and in the resin fine particles made of polyethylene, the above (Y) / (X) is 0. It is .3 to 0.8, and in the resin fine particles made of polypropylene, the above (Y) / (X) is more preferably 0.05 to 0.5.

Commercially available products can be used for the water-dispersed olefin resin fine particles as described above, and the commercially available products include Arrowbase SB-1200, SD-1200, SE-1200, TC-4010, and TD-4010 manufactured by Unitika Ltd. , Sumitomo Chemical's Seixen AC, A, AC-HW-10, L, NC, N, etc., Mitsui Chemicals' Chemipal S100, S200, S300, V100, V200, V300, W100, W200, W300, W400, Examples thereof include W4005, WP100, Hardlen NZ-1004 and NZ-1015 manufactured by Toyobo Co., Ltd., and Hi-Tech S-3121 manufactured by Toho Chemicals Co., Ltd. ..

Water is preferably used as the dispersion medium for the water-dispersed olefin-based resin fine particles (B) used in the present invention, but a liquid medium compatible with water is used for stabilization of the resin fine particles and the like. Is also good. Liquid media compatible with water include alcohols, glycols, cellosolves, aminoalcohols, amines, ketones, carboxylic acid amides, phosphate amides, sulfoxides, carboxylic acid esters, and phosphate esters. , Ethers, nitriles and the like, and may be used as long as they are compatible with water.

The volume average particle diameter (BV1) of the water-dispersed olefin-based resin fine particles (B) used in the present invention is 0.05 to 0.05 from the viewpoint of productivity, stability of the water-dispersed olefin-based resin fine particles, and internal resistance of the power storage device. 1 μm is preferable.

The average particle size in the present invention represents the volume average particle size (MV) and can be measured by a dynamic light scattering method. The average particle size can be measured by the dynamic light scattering method as follows. Water-dispersed The olefin-based resin fine particle dispersion is diluted 200 to 1000 times with water depending on the solid content. Approximately 5 ml of the diluted solution is injected into a cell of a measuring device [Nanotrack manufactured by Nikkiso Co., Ltd.], and the measurement is performed after inputting the refractive index conditions of the solvent (water in the present invention) and the resin according to the sample.

<Water-soluble multivalent metal compound (C)>
The water-soluble polyvalent metal compound (C) in the present invention is a metal compound that becomes a divalent or higher valent metal ion in an aqueous solution.

Water-soluble polyvalent metal compounds include cationic metal ions Ba ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ni ²⁺ , Zn ²⁺ , Cu ²⁺ , Fe ²⁺ , and Co ^{2+. , Sn 2+, Mn 2+, Al} 3+, Fe 3+, Cu 3+, Cr 3+, Sn 4+ and hydroxide ions (OH ^-) is an anionic ion, carbonate ion (CO ₃ ^{2 -),} nitrate ion (NO ₃ ^-), nitrite (NO ₂ ^-), sulfate ion (SO ₄ ^2-), phosphate ion (PO ₄ ^3-), hydrogen phosphate ions (HPO ₄ ^2-) acetate ion ^{_{(C 2 H 3 O 2 -}} ), cyanide ion (CN ^-), thiocyanate ion (SCN ₂ ^-), fluoride ion (F ^-), hexafluorosilicic acid ions (SiF ₆ ^2-), chlorides ion (Cl ^-), chlorate ion (ClO ₃ ^-), chlorite ion (ClO ₂ ^-), perchlorate ion (ClO ^-), bromide ion (Br ^-), bromate ion (BrO ₃ ^-), permanganate ion (MnO ₄ ^-), chromate ion (CrO ₄ ^2-), formate ions (HCO ₂ ^-), benzoic acid ion ^{_{(C 7 H 5 O 2 -}} ), oxalate (C ^₂ O _{4 2} ^- ), Compounds composed of a combination with tartrate ion (C ₄ H ₄ O ₆ ^2- ), etc., but are not limited to these, and two or more kinds of compounds may be used in combination.

When the internal temperature of the power storage device rises due to the binding of the olefin-based resin fine particles (B) via the water-soluble polyvalent metal, the contact between the conductive carbon materials due to the volume expansion of the olefin-based resin is pulled. The peeling effect can be enhanced.

As the water-soluble polyvalent metal, it is preferable to use a divalent, trivalent or tetravalent metal ion, and it is more preferable to use a divalent or trivalent metal ion, and a divalent metal ion is used. It is more preferable to use it. By using divalent metal ions, beaded aggregated particles are formed, so that the effect of volume expansion on the amount of olefin resin fine particles added is considered to be further enhanced.

It is particularly preferable to use a magnesium or calcium compound because of its availability and the performance of the power storage device.

Examples of the method for adding the water-soluble polyvalent metal compound include the following methods. By adding water-soluble polyvalent metal ions to the water-dispersed olefin-based resin fine particles (B), the particles can be bonded via the polyvalent metal ions to form water-dispersed aggregated fine particles. Even if the water-dispersed agglomerated fine particles are added to a slurry in which a conductive carbon material (A), a water-soluble liquid medium (D), and a surfactant or a water-soluble resin (E) are mechanically dispersed, if necessary. Water-dispersed olefin resin fine particles (B) in a slurry in which an aqueous solution of a conductive carbon material (A), a water-soluble polyvalent metal compound, an aqueous liquid medium (D), and a water-soluble resin (E) are mechanically dispersed. ) May be added, and an aqueous solution of a water-soluble polyvalent metal compound is added to a slurry in which a conductive carbon material (A), a water-soluble resin (E), and an aqueous liquid medium (D) are mechanically dispersed. Water-dispersed olefin resin fine particles (B) may be added to the mechanically dispersed slurry.

As described above, even if the method of adding the aqueous solution of the water-soluble multivalent metal compound is changed, when the internal temperature of the power storage device rises, the contact between the conductive carbon materials due to the volume expansion of the olefin resin is peeled off. The effect is almost the same, and it is considered that the aqueous dispersion particles aggregate via the multivalent metal ion even if the addition method is changed.

In the method of adding the water-soluble polyvalent metal ion to the water-dispersed olefin resin fine particles (B), the agglomerated particle size can be measured, which facilitates control in production, but excessive agglomeration of the particles. In order to suppress gelation due to the above, water-dispersed olefin resin fine particles (B) are often diluted to a certain solid content, and then a polyvalent metal ion aqueous solution is added. If necessary, a concentration step is added for production. Processes may be added. On the other hand, in the method of adding water-soluble multivalent metal ions to the slurry, the above concentration step is often unnecessary, but it becomes difficult to control the particle size in the production. From the above viewpoint, the manufacturing method can be used properly as needed.

The water-dispersed agglomerated fine particles composed of the volume average particle diameter (BV1) of the water-dispersed olefin-based resin fine particles (B) of the present invention, the water-dispersed olefin-based resin fine particles (B), and the water-soluble polyvalent metal compound (C). The ratio BV2 / BV1 to the volume average particle size (BV2) is preferably 1.1 to 5.0, preferably 1.2 to 4 from the viewpoint of productivity, stability of water-dispersed agglomerated fine particles, and internal resistance of the power storage device. .0 is even more preferred.

<Aqueous liquid medium (D)>
Water is preferably used as the aqueous liquid medium (D) used in the present invention, but if necessary, for example, a liquid medium compatible with water in order to improve the coatability on the current collector. May be used.

Liquid media compatible with water include alcohols, glycols, cellosolves, aminoalcohols, amines, ketones, carboxylic acid amides, phosphate amides, sulfoxides, carboxylic acid esters, and phosphate esters. , Ethers, nitriles and the like, and may be used as long as they are compatible with water.

Further, a surfactant, a film forming aid, a defoaming agent, a leveling agent, a preservative, a pH adjusting agent, a viscosity adjusting agent and the like can be added to the conductive composition as needed.

The surfactant used in the present invention is not particularly limited as long as it can disperse a conductive carbon material. For example, the nonionic surfactant includes an ester type such as glycerin fatty acid ester and polyoxy. Examples thereof include ether types such as ethylene alkylphenyl ether. Examples of the ionic surfactant include monoalkyl sulfate of an anionic surfactant and alkylbenzene sulfonate, and examples of the cationic surfactant include dialkyldimethylammonium. Examples thereof include salts and alkylbenzyldimethylammonium salts, but the present invention is not limited to these, and two or more kinds may be used in combination.

<Water-soluble resin (E)>
The water-soluble resin (E) of the present invention is obtained by putting 1 g of the water-soluble resin (E) in 99 g of water at 25 ° C., stirring the mixture, leaving the resin at 25 ° C. for 24 hours, and then releasing the resin in water without separation and precipitation. It is soluble.

The water-soluble resin (E) is not particularly limited as long as it is a resin exhibiting water solubility as described above, but for example, acrylic resin, polyurethane resin, polyester resin, polyamide resin, polyimide resin, polyallylamine resin, and the like. Examples thereof include polymer compounds containing polysaccharide resins such as phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicon resin, fluororesin, and carboxymethyl cellulose. Further, as long as it is water-soluble, a modified product, a mixture, or a copolymer of these resins may be used. These water-soluble resins may be used alone or in combination of two or more.

The molecular weight of the water-soluble resin (E) is not particularly limited, but the mass average molecular weight is preferably 5,000 to 2,000,000. The mass average molecular weight (Mw) indicates the polyethylene oxide-equivalent molecular weight in gel permeation chromatography (GPC).

<Other additives>
Further, a surfactant, a film forming aid, a defoaming agent, a leveling agent, a preservative, a pH adjusting agent, a viscosity adjusting agent and the like can be added to the conductive composition as needed.

<Distributor / Mixer>
As an apparatus used for obtaining the conductive composition of the present invention or the mixture ink described later, a disperser or a mixer usually used for pigment dispersion or the like can be used.
For example, mixers such as Dispar, Homo Mixer, or Planetary Mixer; Homogenizers such as "Clear Mix" manufactured by M Technique, or "Fill Mix" manufactured by PRIMIX; Paint Conditioner (manufactured by Red Devil), Ball Mill, Sand Mill. (Symmal Enterprises "Dyno Mill" etc.), Atwriter, Pearl Mill (Eirich "DCP Mill" etc.), or media type disperser such as Coball Mill; Wet Jet Mill (Genus "Genus PY", Sugino) Medialess dispersers such as Machine's "Starburst", Nanomizer's "Nanomizer"), M-Technique's "Claire SS-5", or Nara Machinery's "MICROS"; or other roll mills, etc. These are, but are not limited to. Further, as the disperser, it is preferable to use one that has been subjected to metal contamination prevention treatment from the disperser.

For example, when using a media-type disperser, a method in which the agitator and vessel use a disperser made of ceramic or resin, or a disperser in which the surface of the metal agitator and vessel is treated with tungsten carbide spraying or resin coating. Is preferably used. As the medium, it is preferable to use glass beads, zirconia beads, or ceramic beads such as alumina beads. Also, when a roll mill is used, it is preferable to use a ceramic roll. As the dispersive device, only one type may be used, or a plurality of types of devices may be used in combination. Further, in the case of a positive or negative electrode active material in which particles are easily cracked or crushed by a strong impact, a medialess disperser such as a roll mill or a homogenizer is preferable to a media type disperser.

<Current collector with base layer for power storage device, electrode for power storage device>
The current collector with a base layer for a power storage device of the present invention has a base layer formed from the conductive composition of the present invention on the current collector.
Further, the electrode for a power storage device of the present invention is a composition for forming an electrode (mixture material) containing a base layer formed from the conductive composition of the present invention on a current collector, an electrode active material and a binder. It has a mixture layer formed from ink).

<Current collector>
The material and shape of the current collector used for the electrode are not particularly limited, and those suitable for various power storage devices can be appropriately selected. For example, examples of the material of the current collector include metals and alloys such as aluminum, copper, nickel, titanium, and stainless steel. In the case of a lithium ion battery, aluminum is particularly preferable as the positive electrode material, and copper is preferable as the negative electrode material. Further, as the shape, a foil on a flat plate is generally used, but a foil with a roughened surface, a foil with holes, and a mesh-shaped current collector can also be used.

<Underground layer>
The conductive composition for forming an underlayer of an electrode for a power storage device of the present invention can be applied and dried on a current collector to form an underlayer.
The method of applying the conductive composition or the mixture ink described later on the current collector is not particularly limited, and a known method can be used. Specifically, the die coating method, the dip coating method, the roll coating method, the doctor coating method, the knife coating method, the spray coating method, the gravure coating method, the screen printing method, the electrostatic coating method, etc. can be mentioned and dried. As a method, a stand-drying dryer, a blower dryer, a warm air dryer, an infrared heater, a far-infrared heater, etc. can be used, but the method is not particularly limited, and after coating, a rolling process using a planographic press, a calendar roll, or the like is used. May be done.

The thickness of the base layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, still more preferably 0.5, from the viewpoint of the energy density of the power storage device and the increase in resistance when the power storage device generates heat. It is ~ 3 μm.

<Mixed ink>
The mixture ink refers to a liquid or paste of an active material, a binder, a solvent, etc., which are constituents of an electrode used in a power storage device, and is also used in the electrode for a power storage device of the present invention. The active material and solvent are essential, and if necessary, a conductive auxiliary agent and a binder are contained.
The active material is preferably contained as much as possible, and for example, the ratio of the active material to the solid content of the mixture ink is preferably 80 to 99% by mass. When the conductive auxiliary agent is contained, the ratio of the conductive auxiliary agent to the solid content of the mixture ink is preferably 0.1 to 15% by mass. When a binder is contained, the ratio of the binder to the solid content of the mixture ink is preferably 0.1 to 15% by mass.

Although it depends on the coating method, the viscosity of the mixture ink is preferably 100 mPa · s or more and 30,000 mPa · s or less in the range of solid content 30 to 90% by mass.

The solvent (dispersion medium) of the mixture ink is not particularly limited, but it can be used properly according to the binder used. For example, when a resin-type binder is used, a solvent capable of dissolving the resin is used, and when an emulsion-type binder is used, it is preferable to use a solvent capable of maintaining the dispersion of the emulsion. Examples of the solvent include amides such as dimethylformamide, dimethylacetamide and methylformamide, amines such as N-methyl-2-pyrrolidone (NMP) and dimethylamine, ketones such as methylethylketone, acetone and cyclohexanone, and alcohols. Examples thereof include glycols, cellosolves, aminoalcohols, sulfoxides, carboxylic acid esters, phosphoric acid esters, ethers, nitriles, water and the like. Further, if necessary, two or more kinds of the above solvents may be used in combination. For example, when polyvinylidene fluoride (PVDF) is used as a binder, NMP capable of dissolving PVDF is preferably used, and when carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) are used as a binder, CMC is dissolved to dissolve SBR. Water capable of maintaining dispersion is preferably used.

The active material used in the mixture ink will be described below.

The positive electrode active material for the lithium ion secondary battery is not particularly limited, but a metal oxide capable of doping or intercalating lithium ions, a metal compound such as a metal sulfide, a conductive polymer, or the like is used. be able to.

Examples thereof include oxides of transition metals such as Fe, Co, Ni and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , layered lithium nickel oxide, lithium cobalt oxide, lithium manganate, lithium manganate having a spinel structure, etc. Examples thereof include a composite oxide powder of lithium and a transition metal, a lithium iron phosphate-based material which is a phosphoric acid compound having an olivine structure, and a transition metal sulfide powder such as TiS ₂ and FeS.

Further, a conductive polymer such as polyaniline, polyacetylene, polypyrrole, or polythiophene can also be used. Further, the above-mentioned inorganic compounds and conductive polymers may be mixed and used.

The negative electrode active material for the lithium ion secondary battery is not particularly limited as long as it can be doped with or intercalated with lithium ions. For example, metal Li, alloys such as tin alloys, silicon alloys and lead alloys, metal oxides such as lithium titanate, lithium vanadium and lithium siliconate, conductivity such as polyacetylene and poly-p-phenylene. Amorphous carbonaceous materials such as high molecular weight, soft carbon and hard carbon, artificial graphite such as highly graphitized carbon material, carbon powder such as natural graphite, carbon black, mesophase carbon black, resin calcined carbon material, Air layer growth Carbon fibers, carbon-based materials such as carbon fibers can be mentioned. These negative electrode active materials may be used alone or in combination of two or more.

The electrode active material for the electric double layer capacitor is not particularly limited, and examples thereof include activated carbon, polyacene, carbon whiskers, graphite, and the like, and powders or fibers thereof. The preferred electrode active material for the electric double layer capacitor is activated carbon, specifically, activated carbon activated by phenol-based, coconut husk-based, rayon-based, acrylic-based, coal / petroleum-based pitch coke, mesocarbon microbeads (MCMB), etc. Can be mentioned. Those having a large specific surface area, which can form an interface having a wider area even with the same mass, are preferable. Specifically, the specific surface area of 30 m ² / g or more, preferably preferably 500~5000m ² / g, more preferably 1000~ 3000m ² / g.

These electrode active materials may be used alone or in combination of two or more.

The positive electrode active material for a lithium ion capacitor is not particularly limited as long as it is a material capable of reversibly doping and dedoping lithium ions and anions, and examples thereof include activated carbon powder. The volume average particle size (D50) of the activated carbon is preferably 0.1 to 20 μm. The volume average particle diameter (D50) referred to here is as described above.

The negative electrode active material for the lithium ion capacitor is not particularly limited as long as it is a material capable of reversibly doping and dedoping lithium ions, but for example, graphite-based materials such as artificial graphite and natural graphite are used. Can be mentioned. The volume average particle size (D50) of the graphite-based material is preferably 0.1 to 20 μm. The volume average particle diameter (D50) referred to here is as described above.

The conductive auxiliary agent in the mixture ink is not particularly limited as long as it is a conductive carbon material, and the same conductive carbon material (A) as described above can be used.

The binder in the mixture ink is used to bind particles such as an active material or a conductive carbon material, or a conductive carbon material to a current collector.

Examples of the binder used in the mixture ink include acrylic resin, polyurethane resin, polyester resin, phenol resin, epoxy resin, phenoxy resin, urea resin, melamine resin, alkyd resin, formaldehyde resin, silicon resin, and fluororesin. Cellulous resins such as carboxymethyl cellulose, synthetic rubbers such as styrene-butadiene rubber and fluororubber, conductive resins such as polyaniline and polyacetylene, and polymer compounds containing fluorocarbon atoms such as polyvinylidene fluoride, vinyl fluoride, and tetrafluoroethylene. Can be mentioned. Further, a modified product, a mixture, or a copolymer of these resins may be used. These binders may be used alone or in combination of two or more.
Further, the binder preferably used in the water-based mixture ink is preferably an aqueous medium, and the form of the aqueous medium binder includes a water-soluble type, an emulsion type, a hydrosol type and the like, and is appropriately selected. be able to.

Further, a film forming aid, a defoaming agent, a leveling agent, a preservative, a pH adjusting agent, a viscosity adjusting agent and the like can be added to the mixture ink as needed.

<Method of manufacturing electrodes>
The conductive composition of the present invention can be applied and dried on a current collector to form a base layer, and a base layer electrode for a power storage device can be obtained.

Alternatively, the conductive composition of the present invention can be applied and dried on a current collector to form a base layer, and a mixture layer can be provided on the base layer to obtain an electrode for a power storage device. The mixture layer provided on the base layer can be formed by using the above-mentioned mixture ink.

<Power storage device>
By using the above electrodes on at least one of the positive electrode and the negative electrode, a power storage device such as a secondary battery or a capacitor can be obtained.

Examples of the secondary battery include a lithium ion secondary battery, a sodium ion secondary battery, a magnesium ion secondary battery, an alkaline secondary battery, a lead storage battery, a sodium sulfur secondary battery, a lithium air secondary battery, and the like. Conventionally known electrolytic solutions, separators, and the like can be appropriately used for each secondary battery.

Examples of the capacitor include an electric double layer capacitor, a lithium ion capacitor, and the like, and an electrolytic solution, a separator, or the like conventionally known for each capacitor can be appropriately used.

<Non-aqueous electrolyte electrolyte>
The case of a lithium ion secondary battery will be described as an example. As the electrolytic solution, a solution containing a lithium-containing electrolyte dissolved in a non-aqueous solvent is used.

Electrolytes include LiBF ₄ , LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₃ C. , LiI, LiBr, LiCl, LiAlCl, LiHF ₂ , LiSCN, LiBPh ₄ (where Ph represents a phenyl group) and the like, but are not limited thereto.

The non-aqueous solvent is not particularly limited, but for example, carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethylmethyl carbonate, and diethyl carbonate;
Lactones such as γ-butyrolactone, γ-valerolactone, and γ-octanoic lactone;
Glymes such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, and 1,2-dibutoxyethane;
Esters such as methylformate, methylacetate, and methylpropionate; sulfoxides such as dimethyl sulfoxide and sulfolane; and
Examples thereof include nitriles such as acetonitrile. Further, each of these solvents may be used alone, or two or more kinds may be mixed and used.

Further, the electrolyte solution can be held in a polymer matrix to form a gel-like polymer electrolyte. Examples of the polymer matrix include, but are not limited to, an acrylate-based resin having a polyalkylene oxide segment, a polyphosphazene-based resin having a polyalkylene oxide segment, and a polysiloxane having a polyalkylene oxide segment.

<Separator>
Examples of the separator include, but are not limited to, polyethylene non-woven fabric, polypropylene non-woven fabric, polyamide non-woven fabric, and those obtained by subjecting them to a hydrophilic treatment.

The structure of the lithium ion secondary battery, the electric double layer capacitor, and the lithium ion capacitor using the conductive composition of the present invention is not particularly limited, but is usually composed of a positive electrode and a negative electrode, and a separator provided as needed. It can be made into various shapes according to the purpose of use, such as a paper type, a cylindrical type, a button type, and a laminated type.

(Example 1)
<Conductive composition>
Calcium nitrate tetrahydrate _{(Ca (NO 3) 2 ·} 4H 2 O) to dissolve put ion exchange water to adjust the aqueous solution of 10 mass% as a calcium (Ca).
Water-dispersed olefin-based resin fine particles (B-1: Arrow base SB-1200, manufactured by Unitica, 25% water-based dispersion liquid (mass average particle diameter (MV) 0.16 μm, modification amount (Y) / (X) 0.58 , Polyethylene)) 960 parts by mass of ion-exchanged water was added to 240 parts by mass, and then 3.6 parts by mass of the above 10% by mass calcium aqueous solution was added under stirring with a disper to obtain aqueous dispersed aggregated fine particles. The volume average particle diameter (MV) of the water-dispersed agglomerated fine particles was 0.53 μm. The obtained aqueous dispersion agglomerated fine particles were heated under reduced pressure using a rotary evaporator and concentrated to 25% by mass.
As a conductive carbon material, 40 parts by mass of acetylene black (A-1: Denka Black HS-100, manufactured by Denka), 1000 parts by mass of ion-exchanged water as an aqueous liquid medium (D), and ether-type nonionic surfactant. 0.4 parts by mass of the agent (Triton X, manufactured by Roche Life Science Co., Ltd.) was placed in a mixer to mix, and further placed in a sand mill for dispersion.
Next, 240 parts by mass of the aqueous dispersion agglomerated fine particles concentrated to 25% by mass were added and mixed with a mixer to obtain a conductive composition (1).

(Volume average particle size (BV1) of water-dispersed olefin resin fine particles and volume average particle size (BV2) of water-dispersed agglomerated fine particles)
Water-dispersed olefin-based resin fine particles or water-dispersed agglomerated fine particles are diluted 200 to 1000 times with water depending on the solid content. Approximately 5 ml of the diluted solution is injected into a cell of Nanotrack (Wave-EX150 manufactured by Nikkiso Co., Ltd.), the dispersion medium (water in the present invention) and the refractive index conditions of the resin according to the sample are input, and then measurement is performed to obtain the obtained product. The volume average particle diameter (MV) was defined as the volume average particle diameter (BV1 or BV2).

(Modification amount of olefin resin fine particles (Y) / (X))
The water-dispersed olefin resin fine particles (B) were placed in an oven at 80 ° C. to remove the dispersion medium, and then dried at 120 ° C. for 30 minutes to obtain a solid substance. This was measured by a total internal reflection measurement method (ATR) using a Fourier transform infrared spectroscope (FT-IR: Spectrum One / 100 manufactured by PerkinElmer).
Modification amount using spectral plotting absorbance against wave numbers, when used as a baseline BX a straight line connecting two points of the point indicating the absorbance at a point and 3000 cm ^-1 indicating the absorbance at 2700 cm ^-1, 2800 Connect the height (maximum absorbance) (X) from the maximum peak derived from the olefin of ~ 3000 cm ^-1 to the baseline BX, and the point showing the absorbance at 1650 m ^-1 and the point showing the absorbance at 1850 cm ^-1 . The ratio (Y) / (X) to the height (maximum absorbance) (Y) from the maximum peak derived from the carbonyl of 1690 to 1740 cm ^-1 to the baseline BY when the straight line was taken as the baseline BY was determined.
(Example 2)
Calcium nitrate tetrahydrate _{(Ca (NO 3) 2 ·} 4H 2 O) to dissolve put ion exchange water to adjust the aqueous solution of 10 mass% as a calcium (Ca).
Water-dispersed olefin-based resin fine particles (B-1: Arrow base SB-1200, manufactured by Unitica, 25% water-based dispersion liquid (mass average particle diameter (MV) 0.16 μm, modification amount (Y) / (X) 0.58 , Polyethylene)) 800 parts by mass of ion-exchanged water was added to 200 parts by mass, and then 3 parts by mass of the above 10% by mass calcium aqueous solution was added under stirring with a disper to obtain aqueous dispersed agglomerated fine particles. The volume average particle diameter (MV) of the water-dispersed agglomerated fine particles was 0.53 μm. The obtained aqueous dispersion agglomerated fine particles were heated under reduced pressure using a rotary evaporator and concentrated to 25% by mass.
25 parts by mass of acetylene black (A-1: Denka Black HS-100, manufactured by Denka) as a conductive carbon material, carboxymethyl cellulose (E-1: CMC Daicel # 1240, manufactured by Daicel Chemical Industries, Ltd.), which is a water-soluble resin. 1000 parts by mass of a 2.5% aqueous solution (25 parts by mass as a solid content) was put into a mixer to mix, and further put into a sand mill for dispersion.
Next, 200 parts by mass of the aqueous dispersion agglomerated fine particles concentrated to 25% by mass were added and mixed with a mixer to obtain a conductive composition (2).

(Examples 3 to 19)
The conductive compositions (3) to (19) of Examples were obtained by the same method as that of the conductive composition (2) except that the composition ratio was changed to that shown in Table 1.

The materials used in the examples and comparative examples are shown below.
(Conductive carbon material (A))
・ A-1: Denka Black HS-100 (manufactured by Denka)
・ A-2: Ketjen Black EC-300J (manufactured by Lion)
(Water-dispersed olefin resin fine particles (B))
B-1: Arrow base SB-1200 (25% solid content aqueous dispersion, volume average particle size (MV) 0.16 μm, denaturation amount (Y) / (X) 0.58, polyethylene) (manufactured by Unitica)
B-2: Arrow base TC-4010 (25% solid content aqueous dispersion, volume average particle size (MV) 0.26 μm, denaturation amount (Y) / (X) 0.14, polypropylene) (manufactured by Unitica)
B-3: Zyxen AC (water dispersion with 30% solid content, volume average particle size (MV) 0.10 μm, denaturation amount (Y) / (X) 0.64, polyethylene) (manufactured by Sumitomo Seika Chemical Co., Ltd.)
B-4: Chemipearl W4005 (40% solid content aqueous dispersion, volume average particle size (MV) 0.57 μm, no denaturation, polyethylene) (manufactured by Mitsui Chemicals, Inc.)
(Water-soluble polyvalent metal compound (C))
· C-1: calcium nitrate tetrahydrate _{(Ca (NO 3) 2 ·} 4H 2 O)
· C-2: Magnesium nitrate hexahydrate _{(Mg (NO 3) 2 ·} 6H 2 O)
· C-3: nickel (II) nitrate hexahydrate _{(Ni (NO 3) 2 ·} 6H 2 O)
· C-4: iron (III) nitrate nonahydrate _{(Fe (NO 3) 3 ·} 9H 2 O)
· C-5: manganese (II) nitrate hexahydrate _{(Mn (NO 3) 2 ·} 6H 2 O)
· C-6: aluminum nitrate nonahydrate _{(Al (NO 3) 3 ·} 9H 2 O)
· C-7: Tin (II) chloride dihydrate (SnCl ₂ · 2H ₂ O)
The water-soluble polyvalent metal compound was dissolved by adding ion-exchanged water so that the metal ion concentration was 10% by mass, and each aqueous solution was adjusted and used.
(Water-soluble resin) (E))
-E-1: CMC Daicel # 1240 (manufactured by Daicel Chemical Industries, Ltd.)
-E-2: Sodium polyacrylate, average molecular weight 10000 (manufactured by Wako Pure Chemical Industries, Ltd.)
・ E-3: Kuraray Poval PVA235 (manufactured by Kuraray)

(Example 20)
25 parts by mass of acetylene black (A-1: Denka Black HS-100, manufactured by Denka) as a conductive carbon material, carboxymethyl cellulose (E-1: CMC Daicel # 1240, manufactured by Daicel Chemical Industries, Ltd.), which is a water-soluble resin. 1000 parts by mass of a 2.5% aqueous solution (25 parts by mass as a solid content) was put into a mixer to mix, and further put into a sand mill to disperse to obtain a slurry.
After adding 3 parts by mass of the 10% by mass calcium aqueous solution described in Example 1 to the above slurry under dispar stirring, water-dispersed olefin resin fine particles (B-1: Arrowbase SB-1200, manufactured by Unitica, 25). % Aqueous dispersion (volume average particle diameter (MV) 0.16 μm, modification amount (Y) / (X) 0.58, polyethylene)) 200 parts by mass was added and mixed with a mixer to form a conductive composition ( 20) was obtained.
(Example 21)
25 parts by mass of acetylene black (A-1: Denka Black HS-100, manufactured by Denka) as a conductive carbon material, carboxymethyl cellulose (E-1: CMC Daicel # 1240, manufactured by Daicel Chemical Industries, Ltd.), which is a water-soluble resin. 1000 parts by mass of a 2.5% aqueous solution (25 parts by mass as a solid content) and 3 parts by mass of the 10% by mass calcium aqueous solution described in Example 1 were put into a mixer to mix them, and then put into a sand mill to disperse the slurry. Obtained.
Next, in the above slurry, water-dispersed olefin-based resin fine particles (B-1: Arrow Base SB-1200, manufactured by Unitica, Inc., 25% aqueous dispersion (volume average particle diameter (MV) 0.16 μm, modification amount (Y) / (X) 0.58, polyethylene)) 200 parts by mass was added and mixed with a mixer to obtain a conductive composition (21).
(Example 22)
Calcium nitrate tetrahydrate _{(Ca (NO 3) 2 ·} 4H 2 O) to dissolve put ion exchange water to adjust the aqueous solution of 10 mass% as a calcium (Ca).
Water-dispersed olefin-based resin fine particles (B-1: Arrow base SB-1200, manufactured by Unitica, 25% water-based dispersion liquid (mass average particle diameter (MV) 0.16 μm, modification amount (Y) / (X) 0.58 , Polyethylene)) 800 parts by mass of ion-exchanged water was added to 200 parts by mass, and then 3 parts by mass of the above 10% by mass calcium aqueous solution was added under stirring with a disper to obtain aqueous dispersed agglomerated fine particles. The volume average particle diameter (MV) of the water-dispersed agglomerated fine particles was 0.53 μm. The obtained aqueous dispersion agglomerated fine particles were heated under reduced pressure using a rotary evaporator and concentrated to 25% by mass.
25 parts by mass of acetylene black (A-1: Denka Black HS-100, manufactured by Denka) as a conductive carbon material, carboxymethyl cellulose (E-1: CMC Daicel # 1240, manufactured by Daicel Chemical Industries, Ltd.), which is a water-soluble resin. 1000 parts by mass of a 2.5% aqueous solution (25 parts by mass as a solid content) was put into a mixer to mix, and further put into a sand mill for dispersion.
Next, 200 parts by mass of the aqueous dispersed agglomerated fine particles and 200 parts by mass of isopropanol concentrated to 25% by mass were added and mixed with a mixer to obtain a conductive composition (28).

(Comparative Example 2)
The conductive composition (23) was obtained with the composition shown in Table 1 by the same method as in Example 1 except that the polyvalent metal compound was not added.
(Comparative Example 3)
A 10% by mass sodium hydroxide aqueous solution was added instead of the polyvalent metal compound, the amount of sodium ion added was 0.36 parts by mass, the mass of sodium ion (Na') and the solid content of the aqueous dispersion olefin resin fine particles (B). The composition shown in Table 1 is a conductive composition by the same method as in Example 1 except that the mixture was added so that the mass ratio to the mass (B') was (Na') / (B') = 0.006. I got the thing (24). As shown in Table 1, it was not possible to obtain water-dispersed agglomerated particles by changing the polyvalent metal compound to a monovalent metal compound.
(Comparative Example 4)
The conductive composition (25) was obtained with the composition shown in Table 1 by the same method as in Example 13 except that the polyvalent metal compound was not added.
(Comparative Example 5)
Calcium nitrate tetrahydrate _{(Ca (NO 3) 2 ·} 4H 2 O) to dissolve put ion exchange water to adjust the aqueous solution of 10 mass% as a calcium (Ca).
70 parts by mass of acetylene black (A-1: Denka Black HS-100, manufactured by Denka Co., Ltd.) as a conductive carbon material, carboxymethyl cellulose (E-1: CMC Daicel # 1240, manufactured by Daicel Chemical Industries, Ltd.), which is a water-soluble resin. 1200 parts by mass of a 2.5% aqueous solution (30 parts by mass as a solid content) was put into a mixer to mix, and further put into a sand mill for dispersion.
Next, 3 parts by mass of the above 10 mass% calcium aqueous solution was added and mixed with a mixer to obtain a conductive composition (26).
(Comparative Example 6)
Water-dispersed olefin-based resin fine particles (B-3: Zyxen AC (solid content 30% aqueous dispersion, volume average particle diameter (MV) 0.10 μm) 167 parts by mass of ion-exchanged water was added to 167 parts by mass, followed by stirring with a disper. Then, 500 parts by mass of the 10% by mass calcium aqueous solution described in Example 1 was added. Resin fine particles aggregated in the obtained water-dispersed aggregated fine particles, and the conductive composition (27) was obtained in the same manner as in Example 10. Although it was prepared, it could not be evaluated thereafter.
(Comparative Example 7)
Sodium polyacrylate having a number average molecular weight (Mn) of 200,000 was added instead of the polyvalent metal compound, the amount of sodium polyacrylate added was 0.06 parts by mass, the mass of sodium polyacrylate (PAN1) and the aqueous dispersion olefin. Table by the same method as in Example 1 except that the system resin fine particles (B) were added so that the mass ratio with the solid content mass (B') was (PAN1) / (B') = 0.001. A conductive composition (29) was obtained with the composition shown in 1. As shown in Table 1, it was not possible to obtain water-dispersed agglomerated particles by changing the polyvalent metal compound to a polymer compound such as sodium polyacrylate.

<Current collector with base layer> (Examples 1 to 22, Comparative Examples 2 to 5, Comparative Example 7)
The conductive compositions (1) to (21), (23) to (26), (28), and (29) were applied on an aluminum foil having a thickness of 20 μm as a current collector using a bar coater. After that, it is heated and dried at 80 ° C., and the current collectors (1) to (21), (23) to (26), (28), (28), with a base layer for a non-aqueous electrolyte secondary battery are adjusted so that the thickness becomes 2 μm. 29) were obtained respectively.

The obtained conductive composition and the current collector with the base layer are shown in Table 1.

<Mixed material ink for positive electrode of lithium ion secondary battery>
LiNi _0.5 Mn _0.3 Co _0.2 O ₂ 93 parts by mass as positive electrode active material, 4 parts by mass of acetylene black (Denka Black HS-100, manufactured by Denka) as a conductive agent, polyvinylidene fluoride (KF polymer # 1300, manufactured by Kureha) as a binder ) 3 parts by mass and 45 parts by mass of N-methylpyrrolidone were added and mixed to prepare a mixed material ink for a positive electrode.

<Mixed material ink for negative electrode of lithium ion secondary battery>
As a negative electrode active material, 98 parts by mass of artificial graphite and 66.7 parts by mass of a 1.5% aqueous solution of carboxymethyl cellulose (CMC Daicel # 1190, manufactured by Daicel Chemical Industries, Ltd.) (1 part by mass as a solid content) are put into a planetary mixer and kneaded. Then, 33 parts by mass of water and 2.08 parts by mass of styrene butadiene emulsion (TRD2001, manufactured by JSR) 48% by mass aqueous dispersion (1 part by mass as solid content) are mixed to mix the negative electrode secondary battery electrode mixture ink. Got

<Positive electrode for lithium ion secondary battery with base layer> (Examples 1 to 22, Comparative Examples 2 to 5, Comparative Example 7)
The above-mentioned mixture ink for the positive electrode of the lithium ion secondary battery is applied onto the current collectors ((1) to (21), (23) to (26), (28), (29) with a base layer for the secondary battery. After coating with a doctor blade, the electrode was heated and dried at 80 ° C. to adjust the degree of texture per unit area of the electrode to 20 mg / cm ^2. Further, a rolling process was performed by a roll press. Positive electrodes (1) to (21), (23) to (26), (28), and (29) having a material layer density of 3.1 g / cm ³ were prepared.

<Positive electrode for lithium-ion secondary battery without base layer> (Positive electrode for Comparative Example 1)
The above-mentioned mixture ink for the positive electrode of a lithium ion secondary battery is applied on an aluminum foil having a thickness of 20 μm as a current collector using a doctor blade, and then heated and dried at 80 ° C. to mark the electrodes per unit area. The amount was adjusted to be 20 mg / cm ² . Further, a rolling process was carried out by a roll press to prepare a positive electrode (22) having a density of a mixture layer of 3.1 g / cm ³ .

<Negative electrode for lithium ion secondary battery> (Negative electrodes for Examples 1 to 22, Comparative Examples 1 to 5, and Comparative Example 7)
The above-mentioned mixture ink for the negative electrode of a lithium ion secondary battery is applied to a copper foil having a thickness of 20 μm as a current collector using a doctor blade, and then heated and dried at 80 ° C. to mark the electrodes per unit area. The amount was adjusted to 12 mg / cm ² . Further, rolling treatment was performed by a roll press to prepare negative electrodes (1) to (26), (28), and (29) having a density of the mixture layer of 1.5 g / cm ³ .

<Laminated Lithium Ion Secondary Battery> (Examples 1 to 22, Comparative Examples 1 to 5, Comparative Example 7)
The positive electrode and the negative electrode shown in Table 2 are punched into 45 mm × 40 mm and 50 mm × 45 mm, respectively, and the separator (porous polypropylene film) inserted between them is inserted into an aluminum laminate bag, vacuum dried, and then the electrolytic solution (electrolyte solution (). After injecting a non-aqueous electrolyte solution in which LiPF ₆ is dissolved at a concentration of 1M into a mixed solvent in which ethylene carbonate and diethyl carbonate are mixed at a ratio of 1: 1 (volume ratio), the aluminum laminate is sealed and laminated. A type lithium ion battery was manufactured. The laminated lithium-ion battery is manufactured in a globe box substituted with argon gas, and after the laminated lithium-ion battery is manufactured, the battery characteristics of the initial resistance, resistance increase, rate characteristics, and cycle characteristics shown below are evaluated. It was.

(Resistance measurement)
A laminated battery subjected to constant current discharge at a discharge end voltage of 3.0 V at a discharge current of 12 mA (0.2 C) was subjected to resistance measurement at 500 kHz with an impedance analyzer (SP-50 manufactured by biologic).
The above-mentioned laminated battery was heated from 25 ° C. to 180 ° C., and resistance was measured at each temperature. The resistance measured at 25 ° C. was defined as the initial resistance, and the quotient of the resistance value measured at 180 ° C. and the resistance value measured at 25 ° C. was defined as the resistance increase. That is, the increase in resistance is expressed by the following (Equation 1).
(Equation 1) Resistance increase = resistance value at 180 ° C / resistance value at 25 ° C Table 2 shows the results of evaluation of the initial resistance and resistance increase according to the following criteria.
-Initial resistance ○: "The initial resistance is smaller than the initial resistance of Comparative Example 1 without a base layer. It is excellent."
Δ: “Initial resistance is equivalent to the initial resistance of Comparative Example 1 without a base layer. Practical level.”
X: "The initial resistance is larger than the initial resistance of Comparative Example 1 without the base layer. It is inferior."
・ Increased resistance ◎: “Increased resistance is more than 10 times the initial resistance. It is particularly excellent.”
◯: “The increase in resistance is 5 times or more and less than 10 times the initial resistance. It is excellent.”
Δ: “The increase in resistance is 3 times or more and less than 5 times the initial resistance. The effect is not sufficient, but it can be used.”
X: "The increase in resistance is less than 3 times the initial resistance. The current blocking effect is low. It is inferior."

(Rate characteristics)
The above-mentioned laminated battery was subjected to charge / discharge measurement using a charge / discharge device (SM-8 manufactured by Hokuto Denko Co., Ltd.).
Constant current constant voltage charging at a charging current of 12mA (0.2C) and a charging termination voltage of 4.2V (after performing a cutoff current of 0.6mA, discharging ends at discharge currents of 12mA (0.2C) and 120mA (2C) Constant current discharge was performed until the voltage reached 3.0 V, and the discharge capacity was determined for each. The rate characteristic is represented by the ratio of 0.2C discharge capacity to 2C discharge capacity, that is, the following (Equation 2).
(Equation 2) Rate characteristic = 2C discharge capacity / 0.2C discharge capacity x 100 (%)
Table 2 shows the results of evaluation based on the following criteria.
-Rate characteristics ○: "Rate characteristics are 80% or more. Especially excellent."
○ △: “Rate characteristics are 75% or more and less than 80%. Excellent.”
Δ: “Rate characteristics are 70 or more and less than 75%. Equivalent to the rate characteristics of Comparative Example 1 without a base layer.”
X: "Rate characteristics are less than 70%. Inferior."

(Cycle characteristics)
After performing constant current constant voltage charging (cutoff current 0.6mA) at a charging current of 60mA and a charging end voltage of 4.2V in a constant temperature bath at 50 ° C., the discharge ending voltage reaches 3.0V at a discharging current of 60mA. The initial discharge capacity was determined by performing constant current discharge up to. This charge / discharge cycle was performed 200 times, and the discharge capacity retention rate (percentage of the 200th discharge capacity with respect to the initial discharge capacity) was calculated. Table 2 shows the results of evaluation based on the following criteria.
-Cycle characteristics ○: "Discharge capacity retention rate is 90% or more. Especially excellent."
○ △: “Discharge capacity retention rate is 85% or more and less than 90%. Excellent.”
Δ: “Discharge capacity retention rate is 80% or more and less than 85%. It is equivalent to the discharge capacity retention rate of Comparative Example 1 without a base layer.”
X: "Discharge capacity retention rate is less than 80%. Inferior."

As shown in Table 2, in Comparative Examples 2 to 4 in which the water-soluble polyvalent metal compound was not contained, a noticeable increase in resistance was not confirmed when the internal temperature of the battery increased, but the examples of the present invention were carried out. As shown in the above, the effect of increasing the internal resistance of the battery was confirmed by adding the multivalent metal ion.
On the other hand, in Comparative Example 1 in which the base layer was not formed and Comparative Example 5 in which the water-dispersed olefin resin fine particles were not contained, no remarkable increase in resistance was observed even when the internal temperature of the battery increased. In Comparative Example 1, since the base layer was not formed, there was no effect of increasing the resistance at the time of heat generation, and in Comparative Example 5, since the water-dispersed olefin-based resin fine particles were not contained, the volume expansion due to heat did not occur, and the carbons were used. It is considered that there is no cutting effect.
In Comparative Example 6, since the excess polyvalent metal ion was added, the resin fine particles aggregated and the conductive composition could not be prepared.
From the above results, according to the present invention, the output characteristics of the battery are excellent, and when the internal resistance of the battery increases due to an internal short circuit or the like, the internal resistance is increased to suppress the current flowing through the short circuit, thereby suppressing the battery. It is possible to provide a conductive composition for forming a non-aqueous electrolyte secondary battery having a function of enhancing the safety of the battery.

<Positive and negative electrode mixture inks for electric double layer capacitors>
Activated carbon (specific surface area 1800 m ² / g) 85 parts, conductive aid (acetylene black: Denka Black HS-100, manufactured by Denka Co., Ltd.) 5 parts, carboxymethyl cellulose (CMC Daicel # 1190, manufactured by Daicel Chemical Industries, Ltd.) 8 as active material Parts, binder (polytetrafluoroethylene 30-J: manufactured by Mitsui / Dupont Fluorochemical Co., Ltd., 60% aqueous dispersion) 3.3 parts (2 parts as solid content) and 220 parts of water are mixed and used for positive and negative electrodes. A material ink was prepared.
<Positive electrode and negative electrode for electric double layer capacitor without base layer (Comparative Example 8 and counter electrode for evaluation)>
The above-mentioned mixture ink for an electric double layer capacitor is applied on an aluminum foil having a thickness of 20 μm as a current collector using a doctor blade, dried by heating, and then rolled by a roll press to increase the thickness of the electrodes. A positive electrode and a negative electrode having a length of 50 μm were prepared.

<Positive electrode and negative electrode for electric double layer capacitor with base layer>
(Examples 23 and 24)
The above-mentioned mixture ink for an electric double layer capacitor is applied onto the current collector (3) with a base layer of Example 3 using a doctor blade, dried by heating at 80 ° C., and then rolled by a roll press. This was carried out to prepare a positive electrode and a negative electrode having a thickness of 50 μm.

<Electric double layer capacitor>
Each of the positive electrode and the negative electrode shown in Table 3 is punched to a diameter of 16 mm, and a separator (porous polypropylene film) inserted between them and an electrolytic solution (1 M of TEMABF ₄ (boron triethylmethylammonium tetrafluoride) in a propylene carbonate solvent) are used. A laminated electric double layer capacitor composed of a non-aqueous electrolyte solution dissolved at a concentration) was prepared. The electric double layer capacitor was carried out in a globe box substituted with argon gas, and after the electric double layer capacitor was prepared, the following electricity was produced. The characteristics were evaluated.

(Charge / discharge cycle characteristics)
The obtained electric double layer capacitor was subjected to charge / discharge measurement using a charge / discharge device.

After charging to a charge end voltage of 2.0 V at a charge current of 10 C rate, constant current discharge was performed until a discharge end voltage of 0 V was reached at a discharge current of 10 C rate. These charge / discharge cycles were set as one cycle, and 5 cycles of charge / discharge were repeated, and the discharge capacity of the 5th cycle was defined as the initial discharge capacity. (The initial discharge capacity is 100% maintenance rate). As the charge / discharge current rate, the magnitude of the current capable of discharging the cell capacity in 1 hour was set to 1C.

Next, charging was performed in a constant temperature bath at 50 ° C. at a charging current of 10 C rate at a charging end voltage of 2.0 V, and then constant current discharge was performed at a discharge current of 10 C rate until the discharge end voltage reached 0 V. This charge / discharge cycle was performed 500 times, and the discharge capacity retention rate (percentage of the 500th discharge capacity with respect to the initial discharge capacity) was calculated (the closer to 100%, the better).

◯: “Discharge capacity retention rate is 95% or more. Especially excellent.”
○ △: “Discharge capacity retention rate is 90% or more and less than 95%. No problem at all.”
Δ: “Discharge capacity retention rate is 85% or more and less than 90%. There is a problem, but it is a usable level.”
X: "Discharge capacity retention rate is less than 85%. There is a practical problem and it cannot be used."

(Resistance measurement)
The resistance of the electric double layer capacitor charged to a charging end voltage of 2.0 V at a charging current of 10 C rate was measured at 500 kHz with an impedance analyzer (SP-50 manufactured by biologic).
The above-mentioned laminated electric double layer capacitor was heated from 25 ° C. to 180 ° C., and resistance was measured at each temperature. The resistance measured at 25 ° C. was defined as the initial resistance, and the quotient of the resistance value measured at 180 ° C. and the resistance value measured at 25 ° C. was defined as the resistance increase. That is, the increase in resistance is expressed by the following (Equation 1).
(Equation 1) Resistance increase = resistance value at 180 ° C / resistance value at 25 ° C Table 3 shows the results of evaluation of the initial resistance and resistance increase according to the following criteria.
-Initial resistance ○: "The initial resistance is smaller than the initial resistance of Comparative Example 8 without the base layer. It is excellent."
Δ: “Initial resistance is equivalent to the initial resistance of Comparative Example 8 without a base layer. Practical level.”
X: "The initial resistance is larger than the initial resistance of Comparative Example 8 without the base layer. It is inferior."
・ Increased resistance ◎: “Increased resistance is more than 10 times the initial resistance. It is particularly excellent.”
◯: “The increase in resistance is 5 times or more and less than 10 times the initial resistance. It is excellent.”
Δ: “The increase in resistance is 3 times or more and less than 5 times the initial resistance. The effect is not sufficient, but it can be used.”
X: "The increase in resistance is less than 3 times the initial resistance. The current blocking effect is low. It is inferior."

<Mixed material ink for positive electrode for lithium ion capacitor>
Activated carbon (specific surface area 1800 m ² / g) 85 parts, conductive aid (acetylene black: Denka Black HS-100, manufactured by Denka Co., Ltd.) 5 parts, carboxymethyl cellulose (CMC Daicel # 1190, manufactured by Daicel Chemical Industries, Ltd.) 8 as active material A mixture of 3.3 parts (2 parts as solid content) of a binder (polytetrafluoroethylene 30-J: manufactured by Mitsui / Dupont Fluorochemical Co., Ltd., 60% aqueous dispersion) was mixed to prepare a mixed material ink for a positive electrode.

<Mixed material ink for negative electrode for lithium ion capacitor>
90 parts of graphite, 5 parts of conductive aid (acetylene black: Denka Black HS-100, manufactured by Denka), and 175 parts of hydroxyethyl cellulose 2% by mass aqueous solution (3.5 parts as solid content) are added to the mixer as the negative electrode active material. Mix and mix 26.3 parts of water and 3.75 parts of styrene-butadiene emulsion (TRD2001, manufactured by JSR, 40% aqueous dispersion) (1.5 parts as solid content) to prepare a mixture ink for negative electrodes. did.

<Positive electrode for lithium ion capacitor with base layer (Example 25)>
The above-mentioned mixture ink for positive electrodes for lithium ion capacitors was applied on the current collector (3) with a base layer of Example 3 using a doctor blade, dried under reduced pressure, and rolled by a roll press. After that, a positive electrode having a thickness of 60 μm was prepared.

<Positive electrode for lithium ion capacitor without base layer (Comparative Example 9)>
The above-mentioned mixture ink for a positive electrode for a lithium ion capacitor is applied onto an aluminum foil having a thickness of 20 μm as a current collector using a doctor blade, dried by heating under reduced pressure, and then rolled by a roll press. A positive electrode having a thickness of 60 μm was prepared.

<Negative electrode for lithium ion capacitor without base layer (Example 25, Comparative Example 9)>
The above-mentioned mixture ink for a negative electrode for a lithium ion capacitor is applied onto a copper foil having a thickness of 20 μm as a current collector using a doctor blade, dried under reduced pressure, and rolled by a roll press. A negative electrode having a thickness of 45 μm was prepared.

<Lithium ion capacitor>
A positive electrode shown in Table 4 and a negative electrode that has been half-doped with lithium ions in advance are prepared in a size of 16 mm in diameter, and a separator (porous polypropylene film) to be inserted between them and an electrolytic solution (ethylene carbonate). A laminated lithium ion capacitor composed of a non-aqueous electrolyte solution in which LiPF ₆ was dissolved at a concentration of 1 M in a mixed solvent in which dimethyl carbonate and diethyl carbonate were mixed at a ratio of 1: 1: 1 (volume ratio) was prepared. Half-doping of lithium ions was carried out by sandwiching a separator between the negative electrode and the lithium metal in a beaker cell and doping the negative electrode with lithium ions so that the amount was about half of the capacity of the negative electrode. The lithium ion capacitor was placed in a globe box substituted with argon gas, and after the lithium ion capacitor was manufactured, the following electrical characteristics were evaluated.

(Charge / discharge cycle characteristics)
The obtained lithium ion capacitor was charged / discharged by using a charging / discharging device.

After charging to a charge end voltage of 4.0 V at a charge current of 10 C rate, constant current discharge was performed until a discharge end voltage of 2.0 V was reached at a discharge current of 10 C rate. These charge / discharge cycles were set as one cycle, and 5 cycles of charge / discharge were repeated, and the discharge capacity of the 5th cycle was defined as the initial discharge capacity. (The initial discharge capacity is 100% maintenance rate).

Next, charging was performed in a constant temperature bath at 50 ° C. at a charging current of 10 C rate at a charging end voltage of 4.0 V, and then constant current discharge was performed at a discharge current of 10 C rate until the discharge end voltage reached 2.0 V. This charge / discharge cycle was performed 500 times, and the discharge capacity retention rate (percentage of the 500th discharge capacity with respect to the initial discharge capacity) was calculated (the closer to 100%, the better).

◯: “Discharge capacity retention rate is 95% or more. Especially excellent.”
○ △: “Discharge capacity retention rate is 90% or more and less than 95%. No problem at all.”
Δ: “Discharge capacity retention rate is 85% or more and less than 90%. There is a problem, but it is a usable level.”
X: "Discharge capacity retention rate is less than 85%. There is a practical problem and it cannot be used."
(Resistance measurement)
A lithium ion capacitor charged to a charging end voltage of 4.0 V at a charging current of 10 C rate was subjected to resistance measurement at 500 kHz with an impedance analyzer (SP-50 manufactured by biological company).
The above-mentioned laminated lithium ion capacitor was heated from 25 ° C. to 180 ° C., and resistance was measured at each temperature. The resistance measured at 25 ° C. was defined as the initial resistance, and the quotient of the resistance value measured at 180 ° C. and the resistance value measured at 25 ° C. was defined as the resistance increase. That is, the increase in resistance is expressed by the following (Equation 1).
(Equation 1) Resistance increase = resistance value at 180 ° C / resistance value at 25 ° C Table 4 shows the results of evaluation of the initial resistance and resistance increase according to the following criteria.
-Initial resistance ○: "The initial resistance is smaller than the initial resistance of Comparative Example 9 without a base layer. It is excellent."
Δ: “Initial resistance is equivalent to the initial resistance of Comparative Example 9 without a base layer. Practical level.”
X: "The initial resistance is larger than the initial resistance of Comparative Example 9 without the base layer. It is inferior."
・ Increased resistance ◎: “Increased resistance is more than 10 times the initial resistance. It is particularly excellent.”
◯: “The increase in resistance is 5 times or more and less than 10 times the initial resistance. It is excellent.”
Δ: “The increase in resistance is 3 times or more and less than 5 times the initial resistance. The effect is not sufficient, but it can be used.”
X: "The increase in resistance is less than 3 times the initial resistance. The current blocking effect is low. It is inferior."

Further, as shown in Tables 3 and 4, it was confirmed that the electric double layer capacitor and the lithium ion capacitor have the same effect as those of the examples of the lithium ion secondary battery.

From the above results, according to the present invention, the output characteristics of the power storage device are excellent, and when the internal temperature of the power storage device rises sharply due to overcharging or an internal short circuit, the internal resistance is increased to suppress the flowing current. This makes it possible to provide a conductive composition for forming a power storage device such as a non-aqueous electrolyte secondary battery having a function of enhancing the safety of the power storage device.

Claims (12)

A water-dispersed olefin-based resin fine particles (A) containing a conductive carbon material (A), water-dispersed olefin-based resin fine particles (B), a water-soluble polyvalent metal compound (C), and an aqueous liquid medium (D). The mass ratio (C') / (B') of the solid content mass (B') of B) to the mass (C') of the metal ion in the water-soluble polyvalent metal compound (C) is 0.001 to 0. .1% by mass of conductive composition
A conductive composition characterized in that the content of the conductive carbon material (A) in the solid content of the conductive composition is 10 to 50% by mass . The content of the conductive carbon material (A) in the solid content of the conductive composition is 10 to 50% by mass, and the content of the water-dispersed olefin-based resin fine particles (B) is 20 to 60% by mass. The conductive composition according to claim 1. The conductive composition according to claim 1 or 2, further comprising water-dispersed agglomerated fine particles composed of water-dispersed olefin-based resin fine particles (B) and a water-soluble polyvalent metal compound (C). The volume average particle diameter (BV1) of the water-dispersed olefin-based resin fine particles (B) is 0.05 to 1 μm, and the above (BV1), the water-dispersed olefin-based resin fine particles (B), and the water-soluble polyvalent metal compound ( The conductivity according to any one of claims 1 to 3, wherein the ratio of the water-dispersed agglomerated fine particles consisting of C) to the volume average particle diameter (BV2) and BV2 / BV1 is 1.1 to 5.0. Sex composition. The conductive composition according to any one of claims 1 to 4, further comprising a water-soluble resin (E) in an amount of 10 to 50% by mass. The conductive composition according to any one of claims 1 to 5, wherein the water-dispersed olefin resin fine particles (B) are modified with at least a carboxylic acid or a carboxylic acid ester. The conductive composition according to any one of claims 1 to 6, wherein the conductive composition is used for forming a base layer of an electrode for a power storage device. Water-dispersed olefin resin fine particles (B) are added to a slurry in which a conductive carbon material (A), a water-soluble resin (E), an aqueous liquid medium (D), and a water-soluble polyvalent metal compound (C) are dispersed. The method for producing a conductive composition according to any one of claims 5 to 7 to be added. A slurry in which a conductive carbon material (A), a water-soluble resin (E), and an aqueous liquid medium (D) are dispersed is mixed with water-dispersed olefin resin fine particles (B) and a water-soluble polyvalent metal compound (C). The method for producing a conductive composition according to any one of claims 5 to 7. A current collector with a base layer for a power storage device, which has a current collector and a base layer formed from the conductive composition according to any one of claims 1 to 7. The current collector, the base layer formed from the conductive composition according to any one of claims 1 to 7, and the mixture layer formed from the electrode forming composition containing the electrode active material and the binder. Electrodes for power storage devices. A power storage device including a positive electrode, a negative electrode, and an electrolytic solution, wherein at least one of the positive electrode and the negative electrode is the electrode for the power storage device according to claim 11.