JP5930857B2 - Battery manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a battery having an electrode whose resistance changes with increasing temperature.

  Lithium ion secondary batteries typically have a positive electrode including a composite metal oxide containing lithium as an active material, a negative electrode including a carbon material as a negative electrode active material, a polyolefin porous membrane separator that insulates between the positive and negative electrodes, and a non-aqueous system. Batteries with electrolytes sealed in containers, satisfying high energy density and high output density, so they are widely used from small ones for electronic devices to large ones for electric vehicles and smart grid power storage. .

  However, the lithium ion secondary battery has a high energy density and a high output density, and thus has a property of causing a rapid reaction. For example, the internal temperature of the battery rises due to a large amount of current flowing instantaneously due to a short circuit caused by local impact or the like due to oxidative decomposition of the electrolyte due to overcharge, and as a result, the electrolyte in the battery In some cases, the decomposition reaction of the positive electrode material is promoted and the battery temperature further rises to cause thermal runaway, or the gas generated by the decomposition reaction increases the internal pressure of the battery and the battery expands. Therefore, the lithium ion secondary battery needs a sufficient countermeasure against the reaction that occurs rapidly.

  In view of this, it has been proposed to incorporate a PTC (positive temperature coefficient) element into the battery, in which a rise in internal pressure is released by a safety valve, or a resistance that increases in response to heat generated by a short circuit to cut off current. However, the safety valve is effective when gas is already generated, and the PTC element is installed at a position away from the electrode part where the temperature directly increases, so the temperature of the entire battery is increased. The effect appears for the first time. Therefore, these are highly effective as safety parts that operate after a large amount of heat is generated in the battery. However, in order to further increase the reliability, a measure that operates immediately after the battery generates heat is required.

  Since heat generation at the time of short-circuiting of the lithium ion secondary battery is caused by the short-circuit current and the internal resistance, it can be prevented by suppressing the short-circuit current. Therefore, the porous membrane separator made of polyolefin disposed between the positive and negative electrodes has a shutdown characteristic in which the ion conductivity is lowered and the short circuit current is attenuated by the pores of the separator being closed by being softened or melted by heat. What you have is used. However, the separator in the part away from the heat generating part does not always melt, and when the temperature rises further, the separator melts and contracts, so that the function of electrically insulating the positive and negative electrodes is lost, causing a short circuit. Range may increase.

Moreover, an electrode configuration having PTC characteristics has been proposed as a mechanism for suppressing heat generation due to a short-circuit current. Since the electrode itself has PTC characteristics, the short circuit current is expected to decay quickly because the conductivity of the nearby electrodes is reduced due to the heat generated by the short circuit current.
For example, in Patent Document 1 below, a layer having PTC characteristics is provided on the positive electrode so as to extend substantially parallel to the positive electrode current collector. Patent Document 2 below is an electrode structure including a powder having PTC characteristics in at least one of a positive electrode active material layer and a negative electrode active material layer. Moreover, in the following Patent Document 3, an electrode structure is used in which at least one of a positive electrode and a negative electrode includes an electronic conductive material having a PTC characteristic composed of an electronic conductive filler and a resin.

JP 2008-243708 A JP-A-2005-123185 Japanese Patent No. 40111852

  However, in the battery structure shown in Patent Document 1, since the PTC layer is formed on the positive electrode current collector and the positive electrode active material layer is stacked on the positive electrode current collector, the number of bonding interfaces increases and the contact resistance increases. End up. Moreover, since the number of manufacturing steps increases, the manufacturing cost increases.

  Patent Documents 2 and 3 both have a structure in which a conductive material having PTC characteristics is added to the electrode active material layer. However, the PTC that sufficiently attenuates the short-circuit current when the temperature rises in a battery having these structures. In order for the characteristics to be manifested, it is necessary that the conductive material having the PTC characteristic is responsible for most of the electronic conductivity in the electrode active material layer layer, and it is necessary to add a large amount of the conductive material, and the internal resistance of the battery A sufficient amount of a conductive additive for reducing the battery resistance cannot be added, resulting in an increase in battery resistance.

  If a large amount of conductive material is added in order to increase the effect of the PTC characteristics, the energy density per volume is reduced, so that the high energy density, which is a feature of the lithium ion secondary battery, is impaired. When a sufficient amount of the agent is added, even if the resistance of the conductive material is increased during heat generation due to a short circuit or the like, the portion other than the conductive material becomes a conductive path, so that the short circuit current is not attenuated.

In order to solve the above problems, an object of the present invention, in a broad sense, is to provide a method for manufacturing a battery that quickly attenuates a short-circuit current without increasing the characteristics of the battery .

In the present invention, an active material layer paste is produced by dispersing one or more kinds of an active material for an active material layer and an electronic conductive material having a PTC characteristic whose electrical resistance increases as temperature rises in a dispersion medium. In the step of forming the active material layer paste on the current collector by generating the active material layer paste by the step of applying the active material layer paste to one surface of the current collector once, A conductive material is produced by coating one or more of carbon powder, metal powder, metal nitride, metal carbide, and metal boride with a resin, and the active material is dispersed in a dispersion medium to produce a dispersion. In the battery manufacturing method , the viscosity of the dispersion is reduced to mix the electronic conductive material having a specific gravity greater than that of the active material to produce the active material layer paste .

In this invention, since the electronic conductive material having PTC characteristics has a higher content in the vicinity of the current collector of the active material layer, even if a large amount of the electronic conductive material is not added, the vicinity of the current collector of the active material layer It can greatly contribute to the electron conductivity of. The short-circuit current takes a path that passes through the interface between the active material layer and the current collector. Therefore, the short-circuit current can be effectively attenuated when the battery generates heat due to the short-circuit and the electronic conductive material exhibits PTC characteristics. It becomes.
Further, since this active material layer can be formed in one step, it is not necessary to change or add specifications in the battery manufacturing process.

It is a partial cross section schematic diagram of the battery main part for demonstrating the battery structure concerning Embodiment 1 of this invention. 1 is an overall cross-sectional configuration diagram of a cylindrical battery as an example of a battery according to the present invention. FIG. 3 is a partial cross-sectional schematic diagram for explaining a basic configuration of an active material layer (common to a negative electrode active material layer and a positive electrode active material layer) of a battery according to the present invention. It is a figure for demonstrating the electrical resistivity change of the electrode which concerns on this invention.

Hereinafter, a battery manufacturing method according to the present invention will be described with reference to the drawings according to each embodiment. In each embodiment, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. The drawings are simplified and the dimensions and shapes are not necessarily accurate.

In the present invention, in particular, an electrode having PTC characteristics for suppressing a short-circuit current, which is expected to be highly effective in suppressing an increase in internal temperature of the lithium ion secondary battery, is applied. Provided is a method of manufacturing a lithium ion secondary battery that quickly attenuates a short-circuit current when the temperature rises without impairing a certain high energy density and high output density. Therefore, a lithium ion secondary battery will be described as an example of the battery according to the embodiment. However, the present invention is not limited to this, and can be applied to primary batteries such as lithium / manganese dioxide batteries and other secondary batteries. Furthermore, the present invention can also be applied to aqueous solution type primary batteries and secondary batteries. Furthermore, the present invention can be applied to primary and secondary batteries such as a stacked type, a wound type, and a button type regardless of the battery shape.

Embodiment 1 FIG.
FIG. 1 is a partial cross-sectional schematic view of a main part of a battery for explaining a battery configuration according to Embodiment 1 of the present invention. The battery of this embodiment includes a negative electrode 1 in which a negative electrode active material layer 4 is formed on a negative electrode current collector 6, a positive electrode 2 in which a positive electrode active material layer 5 is formed on a positive electrode current collector 7, and a positive electrode 2 And the separator 3 sandwiched between the negative electrodes 1.

  FIG. 2 is an overall cross-sectional configuration diagram of a cylindrical battery which is an example of the battery according to the present invention. In practice, the battery according to the present invention is, for example, an electrolyte solution (not particularly shown) in a state in which a laminated body 12 including a negative electrode 1, a positive electrode 2, and a separator 3 shown in FIG. 1 is wound in a spiral shape as shown in FIG. ) And sealed in a sealed container 11 to take the shape of a battery.

  FIG. 3 is a partial cross-sectional schematic view for explaining the basic structure of the active material layer (shown in common with the negative electrode active material layer 4 and the positive electrode active material layer 5) of the battery according to the present invention. 3, the current collector 67 corresponds to the negative electrode current collector 6 or the positive electrode current collector 7 in FIG. 1, and the portions of the negative electrode active material layer 4 or the positive electrode active material layer 5 in FIG. The conductive material 45C is configured to include a conductive auxiliary agent 45B as necessary. This configuration is applied to at least one of the positive electrode 2 and the negative electrode 1.

  In addition, in order to increase the capacity per volume of the battery and to remove moisture inside, the electrolytic solution may be sealed after degassing the exterior container.

  In FIG. 1, the negative electrode current collector 6 and the positive electrode current collector 7 can be used as long as they are stable metals in the battery. Copper is preferably used as the negative electrode current collector 6, and aluminum is preferably used as the positive electrode current collector 7. . The current collectors 6 and 7 can be any shape such as foil, net, and expanded metal, but those having a large surface area such as net and expanded metal are bonded to the active material layers 4 and 5. It is preferable for obtaining strength and for facilitating impregnation of the electrolytic solution after joining.

  The negative electrode active material layer 4 is formed by bonding the negative electrode active material (45A) to the surface of the negative electrode current collector 6 with a binder (not shown). If necessary, a conductive aid (45B) may be added. Examples of the negative electrode active material (45A) used for the negative electrode active material layer 4 include materials that allow lithium ions to enter and exit, such as lithium metal, lithium alloys, carbon materials, and inorganic compounds. As the carbon material, artificial graphite, carbon black and the like are used in addition to scale-like natural graphite. Moreover, a silicon compound, lithium titanate, etc. are used for an inorganic compound. Various materials can be used depending on the type of the battery, but materials having no PTC characteristics are used for these active materials. This is mixed with an electronic conductive material (45C) having PTC characteristics described later.

  The positive electrode active material layer 5 is formed by bonding the positive electrode active material (45A) and the conductive additive (45B) to the surface of the positive electrode current collector 7 with a binder (not shown). Since most of the positive electrode active material (45A) has low conductivity, a configuration in which a certain amount of the conductive auxiliary agent (45B) is added is common. Examples of the positive electrode active material (45A) used for the positive electrode active material layer 5 include a composite oxide of lithium and a transition metal such as cobalt, manganese, nickel, and iron, a chalcogen compound containing lithium, or a composite compound thereof. In addition to the composite oxide, the chalcogen compound, and the composite oxide having various additive elements, various materials can be used depending on the type of battery, but these active materials have PTC characteristics. Use no material. This is mixed with an electronic conductive material (45C) having PTC characteristics described later.

  The conductive auxiliary agent (45B) is added to increase the electronic conductivity in the active material layer. For example, carbon black or graphite material is used as the conductive assistant.

  The binder is used to keep the shape of the electrode stable. For example, a fluorine resin or rubber can be used. As the fluorine-based resin, polyvinylidene fluoride (hereinafter referred to as PVDF), polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer, or the like is used. As the rubber, styrene / butadiene rubber, acrylonitrile rubber or the like is used.

  There are two types of materials for the electronic conductive material (45C) having PTC characteristics. One is a material in which one or more of carbon powder, metal powder, metal nitride, metal carbide, metal boride and the like are coated with a resin, and the other is a metal oxide material having PTC characteristics.

Here, the material in which one or more of carbon powder, metal powder, metal nitride, metal carbide, metal boride and the like are coated with a resin is a structure in which the conductive material is coated with a resin having low conductivity, When the temperature rises, the resin softens, melts, and expands in volume, so that the conductive path is blocked by the resin and the resistance value increases.
Examples of the carbon material include carbon black, graphite, carbon fiber and the like typified by acetylene black, furnace black, lamp black, thermal black, channel black, and the like.
Examples of the metal carbide include TiC, ZrC, VC, NbC, TaC, Mo ₂ C, WC, B ₄ C, and Cr ₃ C ₂ .
Examples of the metal nitride include TiN, ZrN, VN, NbN, TaN, and Cr ₂ N.
The metal borides, e.g. _{TiB2, ZrB 2, NbB 2,} CrB, MoB, a WB like.

  Examples of the resin include high-density polyethylene (melting point: 130 ° C. to 140 ° C.), low density polyethylene (melting point: 110 ° C. to 112 ° C.), polyurethane elastomer (melting point: 140 ° C. to 160 ° C.), polyvinyl chloride (melting point: about 145 ° C. These polymers have a melting point in the range of 90 ° C. or higher and 160 ° C. or lower. In addition, it is preferable to use a crystalline resin as the resin of the electronic conductive material because the volume change rate at the time of temperature increase is increased and the resistance is increased.

  By changing the type of these resins, the temperature at which the PTC characteristics are manifested can be adjusted more widely. However, when a resin having a melting point of 90 ° C. or lower is used, the PTC function is maintained even in the temperature range in which the battery is normally used. If the resin with a melting point of 160 ° C. or higher is used, the battery temperature is already higher when the PTC function is exhibited, so the temperature rise is suppressed. Therefore, a resin having a melting point in the range of 90 ° C. or higher and 160 ° C. or lower is used.

Next, a method for producing a material in which one or more of carbon powder, metal powder, metal nitride, metal carbide, metal boride and the like are coated with a resin will be described.
One or more of carbon powder, metal powder, metal nitride, metal carbide, metal boride, etc. is mixed with a resin having a melting point in the range of 90 ° C. or higher and 160 ° C. or lower in a certain ratio to soften the resin. It knead | mixed, heating to the temperature beyond a point.
Next, the kneaded material was cooled, then sheared roughly, and further pulverized with a jet mill so that the particle diameter of the electronically conductive material was 0.1 to 100 μm. The particle diameter range can be determined with higher accuracy according to the pulverization conditions at this time.

  Here, in the electrode structure of the present invention, the electronic conductive material (45C) contained in the active material layer (4, 5) has a specific gravity greater than that of the active material (45A). For this reason, the material to be coated with the resin was selected so that the specific gravity of the electronic conductive material was larger than that of the active material, and was mixed at a certain ratio.

Further, a metal oxide having a PTC function may be used for the electronic conductive material (45C). As the metal oxide, barium titanate or vanadium oxide can be used.
Further, the temperature at which the PTC function of these metal oxides can be adjusted can be adjusted from the change of the Curie point due to the rare earth doping.

The electrolyte includes an ether solvent such as dimethoxyethane, diethoxyethane, dimethyl ether, and diethyl ether, and an ester solvent such as ethylene carbonate and propylene carbonate, or a mixture of LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) _{3 and} other electrolytes can be used in addition to various types depending on the type of battery.

  In addition to porous thin films such as polyethylene, polypropylene, and fluororesin, various separators can be used depending on the type of battery.

  The electrode active material layers (4, 5) are formed on the current collectors (67, 6, 7) by various paste coating methods such as roll coating, doctor blade, gravure coating, etc. It may be formed. When forming on both surfaces of a current collector, after applying to one surface of the current collector, a step of applying to the other surface is taken.

  Examples will be shown below, but this example is an example of a production method in the content of the present invention, and the present invention is not limited to the content shown in the example.

Example 1.
In Example 1, a positive electrode 2 was manufactured by adding a material having a PTC function to the positive electrode active material layer 5.
As the electron conductive material (45C), a fine powder in which 35 parts by weight of W ₂ C and 45 parts by weight of carbon black were coated with 20 parts by weight of polyethylene to have a specific gravity of about 6.8 was used. In order to make the dispersion uniform in 70 parts by weight (45A) of a positive electrode active material made of LiCoO _2, 1 part by weight (45B) of a conductive additive (for example, KS-6 manufactured by Lonza), and 3.5 parts by weight (binder) of PVDF. Methyl pyrrolidone (hereinafter referred to as NMP) (dispersion medium) was added in several portions and kneaded to prepare good dispersions thereof.
Thereafter, while heating, NMP was further added to lower the viscosity of the dispersion, and then 25.5 parts by weight of the electronic conductive material (45C) was added and mixed to prepare a positive electrode active material layer paste.
Thereafter, the positive electrode active material layer 5 was formed by applying the positive electrode active material layer paste on a 20 μm thick aluminum foil to be the positive electrode current collector 7 to a thickness of 100 μm by the doctor blade method. Here, the specific gravity of LiCoO ₂ (positive electrode active material) is about 5, whereas the specific gravity of the used electronic conductive material is about 6.8, and the specific gravity of the electronic conductive material is larger. The electron conductive material (45C) in the active material layer 5 is collected because an electron conductive material having a large specific gravity in the electrode layer is first deposited during application by sufficiently reducing the viscosity of the positive electrode active material layer paste. In the vicinity of the electric conductors (7, 67), the content ratio is higher, and the structure is such that the distribution is lower on the opposite side, that is, on the opposite side of the current collector. Therefore, the positive electrode active material layer paste may be applied once to the surface on one side of the current collector. After the formed active material layer 5 was dried by air blowing at 80 ° C., the positive electrode 2 in which the positive electrode active material layer 5 having a thickness of 70 μm was formed by a roll press was produced.

Example 2
In Example 2, the negative electrode 1 was manufactured by adding a material having a PTC function to the negative electrode active material layer 4.
Fine powder coated with 25 parts by weight of W ₂ C as an electron conductive material and 55 parts by weight of carbon black as an electron conductive material (45C) having PTC characteristics so that the specific gravity is about 4.5 with 20 parts by weight of polyethylene Was used. Mesophase carbon microbeads (hereinafter abbreviated as MCMB) are used for the negative electrode active material (45A), and 52 parts by weight of MCMB and 7 parts by weight of PVDF (binder) are dispersed with NMP (dispersion medium) multiple times. They were kneaded separately to prepare good dispersions thereof.
Thereafter, NMP was further added to lower the viscosity of the dispersion, and then 41 parts by weight of an electronic conductive material was added and mixed to prepare a negative electrode active material layer paste.
Thereafter, a negative electrode active material layer 4 was formed by applying a negative electrode active material paste on a copper foil having a thickness of 20 μm to be the negative electrode current collector 6 to a thickness of 70 μm by a doctor blade method. Here, the specific gravity of MCMB is 1 to 2, whereas the specific gravity of the used electronic conductive material is about 4.5, and the specific gravity of the electronic conductive material is larger. By making the viscosity of the negative electrode active material layer paste sufficiently low, an electronic conductive material having a large specific gravity in the electrode layer is first deposited at the time of application. Therefore, the electronic conductive material (45C) in the active material layer 4 is collected. In the vicinity of the electric body (6, 67), the content rate is higher, and the structure has a distribution that becomes lower on the opposite side, that is, on the side opposite to the current collector. Therefore, the negative electrode active material layer paste may be applied once to the surface on one side of the current collector. After the formed active material layer 4 was dried by air blowing at 80 ° C., the negative electrode 1 in which the negative electrode active material layer 4 having a thickness of 70 μm was formed by a roll press was produced.

Comparative Example 1
In this comparative example, a positive electrode to which a material having a PTC function was not added was produced.
NMP (dispersion medium) is added to and kneaded with 91 parts by weight of a positive electrode active material composed of LiCoO _2, 6 parts by weight of a conductive additive (for example, KS-6 manufactured by Lonza), and 3 parts by weight of PVDF (binder). Was prepared. Thereafter, a positive electrode active material layer (5) was formed on a 20 μm thick aluminum foil serving as the positive electrode current collector 7 by a doctor blade method to a thickness of 100 μm. The formed active material layer was dried by blow drying at 80 ° C., and then a positive electrode (1) in which a positive electrode active material layer (5) having a thickness of 70 μm was formed by a roll press was produced.

Comparative Example 2
In this comparative example, a negative electrode to which a material having a PTC function was not added was produced.
A negative electrode current collector made of copper foil having a thickness of 20 μm was prepared by using MCMB as the negative electrode active material, and preparing a negative electrode active material paste prepared by dispersing 90 parts by weight of MCMB and 10 parts by weight of PVDF (binder) in NMP (dispersion medium). It apply | coated to 100 micrometers in thickness by the doctor blade method on the body. The formed active material layer was dried by air blowing at 80 ° C., and then a negative electrode (1) in which a negative electrode active material layer (4) having a thickness of 70 μm was formed by a roll press was produced.

Comparative Example 3
In Comparative Example 3, a positive electrode to which an electronic conductive material having a PTC function was added and a structure in which the distribution of the electronic conductive material did not occur in the active material layer was produced.
A fine powder in which 35 parts by weight of W ₂ C and 45 parts by weight of carbon black were coated with 20 parts by weight of polyethylene to have a specific gravity of about 6.8 was used as the electron conductive material. 70 parts by weight of a positive electrode active material made of LiCoO _{2, 1} part by weight of a conductive additive (for example, KS-6 manufactured by Lonza), 3.5 parts by weight of PVDF (binder), and 25.5 parts by weight of an electronic conductive material are uniformly dispersed. NMP (dispersion medium) was added and kneaded in several batches so that a good dispersion was prepared to prepare a positive electrode active material layer paste. Thereafter, the positive electrode active material layer paste was applied to a thickness of 100 μm by a doctor blade method on an aluminum foil having a thickness of 20 μm to be the positive electrode current collector (7) without dilution, thereby forming a positive electrode active material layer. The formed active material layer was dried by blow drying at 80 ° C., and then a positive electrode (2) in which a positive electrode active material layer (5) having a thickness of 70 μm was formed by a roll press was produced.

  A method for evaluating the PTC characteristics of the electrodes (positive electrode and negative electrode) will be described. The electrode was sandwiched between current collectors made of gold-plated copper, and the positive voltage terminal and current terminal were connected to one current collector, and the negative voltage terminal and current terminal were connected to the other current collector. . Install a heater on the current collector plate, and measure the voltage drop of the device with a constant current while raising the temperature of the electrode in the range of 25 ° C to 150 ° C so that the rate of temperature rise is 5 ° C / min. The resistance value was calculated by

FIG. 4 is a graph showing the ratio between the electrical resistivity at 25 ° C. and the electrical resistivity at 130 ° C. at which PTC was sufficiently developed for the electrodes shown in the above examples and comparative examples. Since the electrodes produced in each of the examples and comparative examples have different electrical resistivity depending on the respective configurations, the PTC is determined by the ratio between the electrical resistivity in the normal temperature environment (25 ° C.) and the electrical resistivity in the temperature rising environment (130 ° C.) The presence or absence of function was evaluated.
As shown in FIG. 4, in Examples 1 and 2, the electrical resistivity increased by about 5 to 8 times at high temperature, and the PTC characteristics were exhibited, so the short circuit current was reduced when the temperature rose. There is expected. In Comparative Example 3, the electrical resistivity is lowered by raising the temperature from 25 ° C. to 130 ° C., but this changes in shape with softening / melting of the resin in the electronic conductive material. This is because the packing density of the electrodes has increased. That is, the short-circuit current cannot be attenuated unless an appropriate electrode configuration is adopted.

  In this invention, at least one of the positive electrode (2) and the negative electrode (1) contains one or more kinds of active material (45A) and an electronic conductive material (45C) having a PTC characteristic that increases in electrical resistance as the temperature increases. The active material layer (4, 5) is formed on the current collector (6, 7), and the electron conductive material (45C) in the active material layer (4, 5) is the current collector. In the vicinity of (6, 7), the content rate is higher, and the structure has a distribution that becomes lower on the side opposite to the current collector. The active material layers (4, 5) further contain a conductive additive (45B). Thereby, the electronic conductive material having PTC characteristics can greatly contribute to the electronic conductivity in the vicinity of the current collector of the active material layer without adding a large amount. The short-circuit current takes a path that passes through the interface between the active material layer and the current collector. Therefore, the short-circuit current can be effectively attenuated when the battery generates heat due to the short-circuit and the electronic conductive material exhibits PTC characteristics. It becomes.

  The electronic conductive material (45C) has a higher specific gravity than the active material (45A). Thereby, the electronic conductive material in the active material layer has a higher content in the vicinity of the current collector, and it is possible to provide a structure having a distribution that is lower on the facing side, that is, on the side opposite to the current collector.

  The electronic conductive material (45C) has a structure in which one or more of carbon powder, metal powder, metal nitride, metal carbide, and metal boride are coated with a resin. This makes it possible to manufacture an electronic conductive material having a specific gravity greater than that of the active material.

  Further, the resin covering the electronic conductive material (45C) has low conductivity and a melting point in the range of 90 ° C. or higher and 160 ° C. or lower. Thereby, an electronic conductive material can express a PTC characteristic in a suitable temperature range.

  Further, the electronic conductive material (45C) may be a metal oxide having PTC characteristics. Even when a metal oxide having PTC characteristics is used, by making an electronic conductive material having a specific gravity greater than that of the active material, the electronic conductive material in the active material layer has a higher content in the vicinity of the current collector, It is possible to provide an electrode having a structure having a distribution that is lowered on the opposite side, that is, on the side opposite to the current collector.

  Also, the active material layer for the active material layer is dispersed by dispersing in the dispersion medium one or more of the active material (45A) and the electronic conductive material (45C) having a PTC characteristic whose electrical resistance increases as the temperature rises. An active material layer is formed on the current collector by a step of generating a paste and a step of once applying the active material layer paste to one surface of the current collector (67). In the step of producing the active material layer paste, an active material (45A) is dispersed in a dispersion medium to produce a dispersion, the viscosity of the dispersion is lowered, and an electronic conductive material having a higher specific gravity than the active material (45A) ( 45C). In this manufacturing method, since the electrode having the PTC characteristic is formed by one application per side, it is possible to provide a structure having the above characteristics without increasing the application process such as stacking.

  DESCRIPTION OF SYMBOLS 1 Negative electrode, 2 Positive electrode, 3 Separator, 4 Negative electrode active material layer, 5 Positive electrode active material layer, 6 Negative electrode collector, 7 Positive electrode collector, 11 Sealed container, 12 Laminated body, 45A Active material, 45B Conductive auxiliary agent, 45C Electroconductive material, 67 Current collector.

Claims (4)

Producing an active material layer paste by dispersing, in a dispersion medium, one or more of an active material for an active material layer and an electronic conductive material having a PTC characteristic that increases in electrical resistance with increasing temperature;
Applying the active material layer paste to one surface of the current collector once;
To form an active material layer on the current collector,
In the step of generating the active material layer paste,
The electronic conductive material is produced by coating one or more of carbon powder, metal powder, metal nitride, metal carbide, and metal boride with a resin,
The active material is dispersed in a dispersion medium to form a dispersion, the viscosity of the dispersion is reduced, and the electronic conductive material having a specific gravity greater than that of the active material is mixed to produce the active material layer paste.
A battery manufacturing method characterized by the above. In the step of once applying the active material layer paste to one surface of the current collector,
  Applying the active material layer paste to one surface of the current collector of at least one of the positive electrode and the negative electrode of the battery;
  2. The battery according to claim 1, wherein the electronic conductive material in the active material layer has a distribution in which the content is higher in the vicinity of the current collector and lower on the side opposite to the current collector. Production method. 3. The method for manufacturing a battery according to claim 1, wherein the step of generating the active material layer paste further includes a conductive additive. 4. 4. The battery production according to claim 1, wherein the resin covering the electronic conductive material has low conductivity and a melting point in a range of 90 ° C. or more and 160 ° C. or less. 5. Method.

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