KR20130085971A - Electrode for electric device, manufacturing method for the same, electrode structure for electric device and electric device - Google Patents

Abstract

PURPOSE: An electrode for electronic device, a production method thereof, an electrode structure for electronic device, and an electronic device are provided to reduce decline in capacity maintenance ratio and to reduce increase in direct current resistance and thickness. CONSTITUTION: An electrode for an electronic device contains at least electrode active material and polyvinylidene fluoride. A peak intensity of the Raman shift measured by the Raman spectroscopy of the electrode for electronic device satisfies the relation of a formula 1. (1) V2/ (V1+V2)>=0.55. In the formula 1, V1 is an integral value of peak intensity at a Raman shift peak band (3000cm^-1 - 2000cm^-1) of polyvinylidene fluoride with a less crystalline property and V2 is an integral value of peak intensity at a Raman shift peak band (2000cm^-1 - 1000cm^-1) of polyvinylidene fluoride with a highly crystalline property.

Description

ELECTRODE FOR ELECTRIC DEVICE, MANUFACTURING METHOD FOR THE SAME, ELECTRODE STRUCTURE FOR ELECTRIC DEVICE AND ELECTRIC DEVICE}

TECHNICAL FIELD This invention relates to the electrode for electrical devices, the manufacturing method of the electrode for electrical devices, the electrode structure for electrical devices, and an electrical device. More specifically, the electric device of the present invention is used as a secondary battery, a capacitor, or the like, for example, in a driving power source or an auxiliary power source for a motor of a vehicle such as an electric vehicle, a fuel cell vehicle, a hybrid electric vehicle, and the like. In addition, the electrode for electrical devices of this invention is used normally as the positive electrode and negative electrode of a secondary battery, and the positive electrode and negative electrode of a capacitor.

Recently, in order to cope with air pollution and global warming, reduction of carbon dioxide emission is eagerly desired. In the automotive industry, there is an expectation that reduction of carbon dioxide emission by introduction of an electric vehicle (EV) or a hybrid electric vehicle (HEV) is expected, and development of electric devices such as a motor-driven secondary battery, which is the key to such practical use, is actively developed. It is done.

As a motor drive secondary battery, the lithium ion secondary battery which has a high theoretical energy attracts attention, and development is progressing rapidly now. The lithium ion secondary battery generally includes a positive electrode formed by applying a positive electrode slurry containing a positive electrode active material to the surface of a current collector, a negative electrode formed by applying a negative electrode slurry containing a negative electrode active material to the surface of a current collector, and between them. The nonaqueous electrolytic solution located in has a structure accommodated in the battery case.

Further improvement of each electrode, a separator, a nonaqueous electrolyte, etc. is important for further improvement of capacity | capacitance characteristics, output characteristics, etc. of a lithium ion secondary battery.

Conventionally, when the coating film thickness of the electrode paint per electrode unit area is increased in order to achieve high energy density, it is difficult to perform appropriate drying, and thus, a non-aqueous type using a drying apparatus of a hot air system for producing electrode for batteries, which can perform appropriate drying. The manufacturing method of the electrode for electrolyte batteries is proposed (refer patent document 1).

Japanese Patent No. 3851195

However, in the electrode for nonaqueous electrolyte batteries obtained by the manufacturing method of the said patent document 1, swelling suppression of polyvinylidene fluoride (PVdF) which is a binder in an electrode is not enough, and the thickness and resistance in an electrode increase. There is a problem that is not sufficiently suppressed. Moreover, also in the nonaqueous electrolyte battery using the electrode for nonaqueous electrolyte batteries obtained by the manufacturing method of the said patent document 1, the fall of capacity retention in a battery, DC resistance (DCR), or the increase of thickness are not fully suppressed. There was a problem.

This invention is made | formed in view of the subject which this prior art has. And the objective is that it is excellent in the swelling suppression performance of polyvinylidene fluoride which is a binder in an electrode, and the manufacturing method of the electrode for electrical devices and the electrode for electrical devices which can reduce the increase of thickness and resistance. To provide. Moreover, it is providing the electrical device which can reduce the fall of capacity | capacitance retention, the increase of DC resistance, and the increase of thickness in the electrical device using the electrode for electrical devices or the electrode structure for electrical devices.

The present inventors made various examinations in order to achieve the said objective. For example, when the amount of water in the electrode is examined, it is confirmed that there is little correlation between the amount of water and the increase in thickness and resistance in the electrode, the increase in thickness or DC resistance in the secondary battery, and the decrease in capacity retention rate. Could.

Therefore, examination of state changes, such as swelling of polyvinylidene fluoride, was repeated. Until now, although the crystallinity of polyvinylidene fluoride itself was specified by X-ray diffraction (XRD) and the crystal phase by Fourier transform infrared spectroscopy (FT-IR), polyvinyl fluoride in an active material layer containing an active material and the like The degree of crystallinity and the crystal phase cannot be specified for the leadene, and the state changes such as swelling of polyvinylidene fluoride, the increase in thickness and resistance in the electrode, the increase in thickness and DC resistance in the secondary battery, and the decrease in capacity retention rate. The relationship with was unclear.

As a result of this inventor's examination again, about the polyvinylidene fluoride in the active material layer containing an active material etc., the polyvinyl fluoride in an active material layer is used by using the Raman shift of polyvinylidene fluoride measured by Raman spectroscopy. It was found that the low crystalline phase and the high crystalline phase of Leeden can be measured.

Moreover, the present inventors earnestly examined in order to achieve the said objective. As a result, in the electrode for electrical devices containing an electrode active material and polyvinylidene fluoride at least, it discovered that the said objective can be achieved by making the peak intensity of the Raman shift measured by Raman spectroscopy satisfy a predetermined relationship. The present invention has been completed.

That is, the electrode for electrical devices of this invention contains an electrode active material and polyvinylidene fluoride at least.

And in the electrode for electrical devices of this invention, the peak intensity of the Raman shift measured by the Raman spectroscopy of the electrode for electrical devices satisfy | fills the relationship of following formula (1).

(Equation 1, V1 is the integral value of the peak intensity of the Raman shift peak band (3000 cm ^-1 to 2000 cm ^-1 ) of low crystalline polyvinylidene fluoride in the electrode, and V2 is high crystallinity in the electrode. The integral value of the peak intensity of the Raman shift peak band (2000 cm <^-1> -1000 cm <^-1> ) of polyvinylidene fluoride is shown.)

Moreover, the electrode structure for electrical devices of this invention is equipped with the positive electrode for electrical devices, the negative electrode for electrical devices, and the separator located between these.

And in the electrode structure for electrical devices of this invention, at least one of the positive electrode for electrical devices and the negative electrode for electrical devices is made into the electrode for electrical devices of the said invention.

Moreover, the electrical device of this invention is equipped with the electrode structure for electrical devices of this invention, a nonaqueous electrolyte solution, and the exterior which accommodates these.

In addition, the 1st manufacturing method of the electrode for electrical devices of this invention is an example of the manufacturing method of the electrode for electrical devices of this invention, and is a manufacturing method containing following (step 1)-(step 4).

(Step 1): step of obtaining an electrode forming slurry containing at least an electrode active material, polyvinylidene fluoride, and a solvent

(Step 2): step of drying the electrode forming slurry to obtain an electrode precursor

(Step 3): step of compression molding the electrode precursor

(Process 4): The process of heat-processing the said compression molded electrode precursor, and obtaining an electrode

Moreover, the 2nd manufacturing method of the electrode for electrical devices of this invention is another example of the manufacturing method of the electrode for electrical devices of this invention, and is a manufacturing method containing following (step 1 ')-(step 3'). .

(Step 1 '): The process of obtaining the slurry for electrode formation containing an electrode active material, polyvinylidene fluoride, and a solvent at least.

(Step 2 '): Step of drying the electrode forming slurry to obtain an electrode precursor

(Process 3 '): The process of heat compression molding the said electrode precursor, and obtaining an electrode.

According to the present invention, in an electrode for an electrical device comprising at least an electrode active material and polyvinylidene fluoride, it is assumed that the peak intensity of the Raman shift measured by Raman spectroscopy of the electrode for electrical device satisfies the relationship of the following formula (1). .

&Quot; (1) &quot;

(Equation 1, V1 is the integral value of the peak intensity of the Raman shift peak band (3000 cm ^-1 to 2000 cm ^-1 ) of low crystalline polyvinylidene fluoride in the electrode, and V2 is high crystallinity in the electrode. The integral value of the peak intensity of the Raman shift peak band (2000 cm <^-1> -1000 cm <^-1> ) of polyvinylidene fluoride is shown.)

Therefore, the manufacturing method of the electrode for electrical devices, and the electrode for electrical devices which can reduce the increase of thickness and resistance can be provided. Moreover, the electrical device which can reduce the fall of capacity | capacitance retention, the increase of DC resistance, and the increase of thickness in the electrical device using the electrode for electrical devices or the electrode structure for electrical devices can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the outline of an example of the lithium ion secondary battery which concerns on one Embodiment of this invention.
It is a graph which shows the peak intensity of the Raman shift measured by Raman spectroscopy of the positive electrode for electrical devices of Example 1-1.
It is a graph which shows the peak intensity of the Raman shift measured by Raman spectroscopy of the positive electrode for electrical devices of Example 1-3.
It is a graph which shows the peak intensity of the Raman shift measured by Raman spectroscopy of the negative electrode for electrical devices of Example 1-5.
It is a graph which shows the peak intensity of the Raman shift measured by Raman spectroscopy of the negative electrode for electrical devices of Example 1-7.
6 is a graph showing the peak intensity of Raman shift measured by Raman spectroscopy of the positive electrode for an electric device of Comparative Example 1-1.
It is a graph which shows the peak intensity of the Raman shift measured by Raman spectroscopy of the negative electrode for electrical devices of the comparative example 1-2.

EMBODIMENT OF THE INVENTION Hereinafter, the electrode for electrical devices, the manufacturing method of the electrode for electrical devices, the electrode structure for electrical devices, and an electrical device of this invention are demonstrated in detail. Moreover, the electrode for electrical devices of this invention can be applied as a positive electrode or a negative electrode of the lithium ion secondary battery which is an electrical device, for example. Therefore, the electrode for lithium ion secondary batteries, the electrode structure for lithium ion secondary batteries, and the lithium ion secondary battery which concern on one Embodiment of this invention are demonstrated in detail, referring drawings for example. Moreover, all the manufacturing method of the electrode for lithium ion secondary batteries is demonstrated in detail. In addition, the dimension ratio of drawing quoted by the following embodiment is exaggerated on account of description, and may differ from an actual ratio.

1 is a cross-sectional view showing an outline of an example of a lithium ion secondary battery according to one embodiment of the present invention. In addition, such a lithium ion secondary battery is called a laminate type lithium ion secondary battery.

As shown in FIG. 1, in the lithium ion secondary battery 1 of the present embodiment, the exterior body 30 in which the battery element 10 provided with the positive electrode lead 21 and the negative electrode lead 22 is formed of a laminate film. It has the structure enclosed in the inside. In the present embodiment, the positive electrode lead 21 and the negative electrode lead 22 are led in the opposite direction from the inside of the exterior body 30 to the outside. In addition, although not shown in figure, the positive electrode lead and the negative electrode lead may be guide | induced in the same direction toward the exterior from the inside of an exterior body. In addition, such a positive electrode lead and a negative electrode lead can be respectively provided in the positive electrode electrical power collector and negative electrode electrical power collector which are mentioned later by ultrasonic welding, resistance welding, etc., respectively.

The positive electrode lead 21 and the negative electrode lead 22 are made of metal materials such as aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), these alloys, stainless steel (SUS), and the like. Consists of. However, it is not limited to these, The conventionally well-known material used as a lead for lithium ion secondary batteries can be used.

Moreover, the thing of the same material may be used for the positive electrode lead and the negative electrode lead, and the thing of a different material may be used. In addition, like this embodiment, the lead prepared separately may be connected to a positive electrode current collector and a negative electrode current collector described later, or a lead may be formed by extending each of the positive electrode current collector and each negative electrode current collector described later. Although not shown in the drawing, the positive electrode lead and the negative electrode lead of the portion taken out from the exterior body are heat-insulated so as not to contact the peripheral device or the wiring and short-circuit to affect the product (for example, automobile parts, especially electronic devices, etc.). It is preferable to coat with a heat shrink tube or the like.

In addition, although not shown, a current collector may be used for the purpose of taking out a current to the outside of the battery. The current collector plate is electrically connected to the current collector or the lead, and is taken out of the laminate film, which is a battery exterior material. The material which comprises a collector plate is not specifically limited, The well-known highly conductive material conventionally used as a collector plate for lithium ion secondary batteries can be used. As the constituent material of the current collector plate, for example, metal materials such as aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), these alloys, stainless steel (SUS), and the like are preferable, and the light weight, corrosion resistance, Aluminum (Al), copper (Cu), etc. are more preferable from a high electrical conductivity viewpoint. In addition, in the positive electrode collector plate and the negative electrode collector plate, the same material may be used, and different materials may be used.

The exterior body 30 is preferably formed of a film-shaped exterior material from the viewpoint of miniaturization and weight reduction, for example, but is not limited to this, and a conventionally known one used in an exterior body for a lithium ion secondary battery can be used. Can be. That is, a metal can case can also be applied.

Moreover, the polymer-metal composite laminate film which is excellent in thermal conductivity is mentioned from a viewpoint that it is excellent in high output and cooling performance, and can be used suitably for the battery for large apparatuses of an electric vehicle and a hybrid electric vehicle. More specifically, the exterior body formed from the exterior material of the laminated film of the laminated film which consists of laminating polypropylene as a thermocompression bonding layer, aluminum as a metal layer, and nylon as an outer protective layer in this order can be used suitably.

In addition, instead of the laminate film described above, the exterior body may be constituted by another structure, for example, a laminate film having no metal material, a polymer film such as polypropylene, a metal film, or the like.

Here, the general structure of an exterior body can be represented by the laminated structure of an outer protective layer / metal layer / thermocompression layer (However, an outer protective layer and a thermocompression layer may be comprised by multiple layers). As the metal layer, it is sufficient to function as a moisture-permeable barrier film, and not only aluminum foil, but also stainless steel foil, nickel foil, plated iron foil, and the like can be used, but a thin, lightweight, and excellent workability aluminum foil can be suitably used. have.

As an exterior body, when the usable structure is enumerated in the form of (outer protective layer / metal layer / thermal compression layer), nylon / aluminum / non-stretched polypropylene, polyethylene terephthalate / aluminum / non-stretch polypropylene, polyethylene terephthalate / aluminum / Polyethylene terephthalate / non-stretched polypropylene, polyethylene terephthalate / nylon / aluminum / non-stretched polypropylene, polyethylene terephthalate / nylon / aluminum / nylon / non-stretched polypropylene, polyethylene terephthalate / nylon / aluminum / nylon / polyethylene, Nylon / polyethylene / aluminum / linear low density polyethylene, polyethylene terephthalate / polyethylene / aluminum / polyethylene terephthalate / low density polyethylene and polyethylene terephthalate / nylon / aluminum / low density polyethylene / non-stretched polypropylene.

As shown in FIG. 1, the battery element 10 includes the positive electrode 11 having the positive electrode active material layer 11B formed on both main surfaces of the positive electrode current collector 11A, the electrolyte layer 13, and the negative electrode current collector ( It has the structure which laminated | stacked the several negative electrode 12 in which the negative electrode active material layer 12B was formed on both main surfaces of 12A). At this time, the negative electrode current collector of the positive electrode active material layer 11B formed on one main surface of the positive electrode current collector 11A of the positive electrode 11 of the reference numeral 1 and the negative electrode 12 adjacent to the positive electrode 11 of the reference numeral 1 ( The negative electrode active material layer 12B formed on one main surface of 12A) faces through the electrolyte layer 13. In this manner, a plurality of layers are stacked in the order of the positive electrode, the electrolyte layer, and the negative electrode.

Thereby, the adjacent positive electrode active material layer 11B, the electrolyte layer 13, and the negative electrode active material layer 12B comprise one unit cell layer 14. Therefore, the lithium ion secondary battery 1 of this embodiment has a structure electrically connected in parallel by plural unit cell layers 14 being laminated | stacked. The positive electrode and the negative electrode may each have an active material layer formed on one main surface of each current collector. In the present embodiment, for example, the negative electrode active material layer 12B is formed only on one surface of the negative electrode current collector 12a located at the outermost layer of the battery element 10.

In addition, in this invention, an "electrode structure" means that the positive electrode, the negative electrode, and another member form some constant structure. As a representative example of the electrode structure 10a, the nonaqueous electrolyte is removed from a battery element composed of a positive electrode and a negative electrode and an electrolyte layer positioned therebetween, and the positive electrode 11 and the negative electrode 12 and the separator 13a positioned therebetween. The thing which consists of) is mentioned.

Moreover, the insulating layer (not shown) for insulating between the adjacent positive electrode collector or negative electrode collector may be formed in the outer periphery of a unit cell layer. Such an insulating layer is preferably formed of a material that holds an electrolyte contained in the electrolyte layer and the like and is formed on the outer circumference of the unit cell layer to prevent leakage of the electrolyte. Specifically, polypropylene (PP), polyethylene (PE), polyurethane (PUR), polyamide-based resin (PA), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), polystyrene (PS) General purpose plastics, such as thermoplastic olefin rubber, etc. can be used. A silicone rubber may also be used.

In this embodiment, the positive electrode active material layers on both main surfaces of the positive electrode current collector in the positive electrode contain at least a positive electrode active material and polyvinylidene fluoride. In addition, the positive electrode active material layer may contain, for example, a conductive assistant and another binder as necessary.

And the peak intensity of the Raman shift measured by Raman spectroscopy of the positive electrode active material layer in a positive electrode satisfy | fills the relationship of following formula (2).

(Equation 2, V'1 is the integral value of the peak intensity of the Raman shift peak band (3000 cm ^-1 to 2000 cm ^-1 ) of the low crystalline polyvinylidene fluoride in the positive electrode, and V'2 is the positive electrode. The integral value of the peak intensity of the Raman shift peak band (2000 cm ^-1 to 1000 cm ^-1 ) of the highly crystalline polyvinylidene fluoride in

In such a positive electrode, preferably in the positive electrode satisfying the relationship of 0.70 on the right side, swelling by the nonaqueous electrolyte of polyvinylidene fluoride is suppressed, and the adhesion between the positive electrode active material, the positive electrode current collector and the conductive aid Since this is maintained, when used for a lithium ion secondary battery, the increase in thickness and resistance can be reduced. For this reason, it is used suitably for the electrode structure for lithium ion secondary batteries, and a lithium ion secondary battery. As a result, it can use suitably as a lithium ion secondary battery for drive power supplies of a vehicle, or an auxiliary power supply. In addition, the present invention can be sufficiently applied to a lithium ion secondary battery for home use or a portable device.

When the equation (2) is not satisfied, that is, when V'2 / (V'1 + V'2) is less than 0.55, the same thickness and resistance increase as in the prior art are generated.

Here, the outline | summary of Raman spectroscopy is demonstrated. When a laser beam is irradiated to a material, some of it is reflected as it is (Rayy scattering). However, due to interaction with the material, weak scattered light (Raman scattered light) having a different wavelength from incident light is generated. From the scattering intensity spectrum with respect to the wavelength change width (Raman shift), the chemical structure of the substance, the crystal structure can be determined, and the unknown substance can be identified. In the present invention, any theoretical Raman spectrometer capable of measuring the peak intensity of the Raman shift of polyvinylidene fluoride can be used without particular limitation in theory, but in reality, a brown rice laser Raman spectrometer (manufactured by Hobashi Co., Ltd.) , LabRAM ARAMIS). In addition, in the completion | finish of this invention and its examination, in the predetermined relationship in this invention, the Raman shift peak band (3000 cm <^-1> -2000 cm <^-1> ) of the low crystalline polyvinylidene fluoride in an electrode. And the method of taking the background in the Raman shift peak band (2000 cm ^-1 to 1000 cm ^-1 ) of the highly crystalline polyvinylidene fluoride confirmed that the effect was small and there was no problem. Moreover, the same thing was confirmed about not only a positive electrode but a negative electrode.

The positive electrode current collector 11A is made of a conductive material. The size of the current collector can be determined according to the use of the battery. For example, a current collector having a large area is used as long as it is used for a large battery requiring high energy density. The thickness of the current collector is not particularly limited. The thickness of the current collector is usually about 1 to 100 mu m. The shape of the current collector is not particularly limited either. In the battery element 10 shown in FIG. 1, in addition to the current collector foil, a mesh shape (expanded grid or the like) or the like can be used.

The material constituting the current collector is not particularly limited. Typically, a metal can be employed. Specific examples of the metal include aluminum (Al), nickel (Ni), iron (Fe), stainless steel (SUS), titanium (Ti), copper (Cu), and the like. In addition to these, it is preferable to use a cladding material of nickel (Ni) and aluminum (Al), a cladding material of copper (Cu) and aluminum (Al), or a plating material combining these metals. Moreover, the foil in which aluminum (Al) was coat | covered on the metal surface may be sufficient. Among them, aluminum (Al), stainless steel (SUS), copper (Cu), and nickel (Ni) are preferable from the viewpoint of electronic conductivity, battery operating potential, and the like.

However, it is not limited to these, The conventionally well-known material used as an electrical power collector for lithium ion secondary batteries can be used.

It is preferable that the positive electrode active material layer 11B contains a lithium containing compound from a viewpoint of a capacity | capacitance and an output characteristic, for example as a positive electrode active material. Examples of such lithium-containing compounds include complex oxides containing lithium and transition metal elements, phosphoric acid compounds containing lithium and transition metal elements, and sulfuric acid compounds containing lithium and transition metal elements. In view of obtaining output characteristics, a lithium-transition metal composite oxide is particularly preferable.

Specific examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (LiCoO ₂ ), lithium nickel composite oxide (LiNiO ₂ ), lithium nickel cobalt composite oxide (LiNiCoO ₂ ), and the like. Moreover, as a specific example of the phosphate compound containing lithium and a transition metal element, a lithium iron phosphate compound (LiFePO ₄ ), a lithium iron manganese phosphate compound (LiFeMnPO ₄ ), etc. are mentioned. Moreover, in these composite oxides, what substituted a part of transition metal with another element etc. for the purpose of stabilizing a structure, etc. are mentioned.

As a binder (binder), if it contains at least polyvinylidene fluoride (PVDF), it will not specifically limit, You may use another binder together. As another binder, the following materials are mentioned, for example.

Polyethylene (PE), Polypropylene (PP), Polyethylene terephthalate (PET), Polyethernitrile (PEN), Polyacrylonitrile (PAN), Polyimide (PI), Polyamide (PA), Cellulose, Carboxymethylcellulose (CMC), ethylene-vinyl acetate copolymer, polyvinyl chloride (PVC), styrene butadiene rubber (SBR), isoprene rubber, butadiene rubber, ethylene propylene rubber, ethylene propylene diene copolymer, styrene butadiene styrene Thermoplastic polymers, such as a block copolymer and its hydrogenated substance, a styrene isoprene styrene block copolymer, and its hydrogenated substance, polytetrafluoroethylene (PTFE), tetrafluoroethylene hexafluoropropylene copolymer (FEP), tetra Fluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), ethylene tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), Fluorine resins, such as a ethylene chloro trifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF), vinylidene fluoride- hexafluoropropylene type fluorine rubber (VDF-HFP type fluorine rubber), and vinylidene fluoride- Hexafluoropropylene-tetrafluoroethylene fluorine rubber (VDF-HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-penta Fluoropropylene-tetrafluoroethylene-based fluororubbers (VDF-PFP-TFE-based fluororubbers), vinylidene fluoride-perfluoromethylvinylether-tetrafluoroethylene-based fluororubbers (VDF-PFMVE-TFE-based fluororubbers) And vinylidene fluoride-based fluorine rubbers such as vinylidene fluoride-chlorotrifluoroethylene-based fluorine rubber (VDF-CTFE-based fluorine rubber) and epoxy resins. Especially, it is preferable to use polyvinylidene fluoride independently, and as a binder other than being used together, polyimide, styrene butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, Polyamide is preferred. These suitable binders are excellent in heat resistance, have a wide potential window, are stable to the positive electrode potential, and can be used for the positive electrode active material layer.

However, it is not limited to these, The well-known material conventionally used as a binder for lithium ion secondary batteries can be used together.

Although content of the binder in a positive electrode active material layer will not be specifically limited if it is an quantity which can bind a positive electrode active material, Preferably it is 0.5-15 mass% with respect to a positive electrode active material layer, More preferably, it is 1-10. It is mass%.

A conductive support agent is mix | blended in order to improve the electroconductivity of a positive electrode active material layer. As a conductive support agent, carbon materials, such as carbon black, such as acetylene black, graphite, and vapor-grown carbon fiber, are mentioned, for example. When a positive electrode active material layer contains a conductive support agent, the electronic network in the inside of a positive electrode active material layer is formed effectively, and can contribute to the improvement of the output characteristic of a battery.

However, it is not limited to these, The conventionally well-known material used as a conductive support agent for lithium ion secondary batteries can be used. These electrically conductive adjuvant may be used individually by 1 type, and may use 2 or more types together.

Moreover, you may use the conductive binder which has the function of the said conductive support agent and a binder instead of these conductive support agents. As the conductive binder, for example, TAB-2 (manufactured by Hosen Industries, Ltd.) which is already commercially available can be used.

In this embodiment, the negative electrode active material layers on both main surfaces of the negative electrode current collector in the negative electrode contain at least a negative electrode active material and polyvinylidene fluoride. In addition, the negative electrode active material layer may contain, for example, a conductive aid and another binder as necessary. And the peak intensity of the Raman shift measured by the Raman spectroscopy of the negative electrode active material layer in a negative electrode satisfy | fills the relationship of following formula (3).

In formula (3), V "1 is the integral value of the peak intensity of the Raman shift peak band (3000 cm <^-1> -2000 cm <^-1> ) of low crystalline polyvinylidene fluoride, and V" 2 is high crystalline polyvinylidene fluoride Raman shift peak to represent the integral of the peak intensity of the ^(-1 to 2000㎝ 1000㎝ ^-1).)

In such a negative electrode, swelling of the polyvinylidene fluoride by the nonaqueous electrolyte solution is suppressed, and the adhesion between the negative electrode active material, the negative electrode current collector and the conductive assistant is maintained, so that when used in a lithium ion secondary battery, an increase in thickness and resistance is achieved. Can be reduced. Therefore, it is used suitably for the electrode structure for lithium ion secondary batteries, and a lithium ion secondary battery. As a result, it can use suitably as a lithium ion secondary battery for drive power supplies of a vehicle, or an auxiliary power supply. In addition, the present invention can be sufficiently applied to a lithium ion secondary battery for home use or a portable device.

When the expression (3) is not satisfied, that is, when V "2 / (V" 1 + V "2) is less than 0.55, the same thickness and resistance increase as in the prior art are generated. Since the negative electrode active material itself tends to swell, it is preferable that the right side of the expression (3) is 0.60, more preferably 0.70 from the viewpoint of increasing the crystallinity.

The negative electrode current collector 12A is made of a conductive material. The size of the current collector can be determined according to the use of the battery. For example, if it is used in a large-sized battery requiring a high energy density, a collector having a large area is used. The thickness of the current collector is not particularly limited. The thickness of the current collector is usually about 1 to 100 mu m. The shape of the current collector is not particularly limited either. In the battery element 10 shown in FIG. 1, in addition to the current collector foil, a mesh shape (expanded grid or the like) or the like can be used.

The material constituting the current collector is not particularly limited. Typically, a metal can be employed. Specific examples of the metal include aluminum (Al), nickel (Ni), iron (Fe), stainless steel (SUS), titanium (Ti), copper (Cu), and the like. In addition to these, it is preferable to use a cladding material of nickel (Ni) and aluminum (Al), a cladding material of copper (Cu) and aluminum (Al), or a plating material combining these metals. Moreover, the foil in which aluminum (Al) was coat | covered on the metal surface may be sufficient. Among them, aluminum (Al), stainless steel (SUS), copper (Cu), and nickel (Ni) are preferable from the viewpoint of electronic conductivity, battery operating potential, and the like.

However, it is not limited to these, The conventionally well-known material used as an electrical power collector for lithium ion secondary batteries can be used.

The negative electrode active material layer 12B contains a negative electrode material which can occlude and release lithium, for example.

Examples of the negative electrode material capable of occluding and releasing lithium include graphite (natural graphite, artificial graphite, and the like), low crystalline carbon (soft carbon, hard carbon), carbon black (Ketjen black, acetylene black, Channel black, lamp black, oil furnace black, thermal black and the like), fullerene, carbon nanotubes, carbon nanofibers, carbon nanohorns, carbon fibrils and the like; Silicon (Si), germanium (Ge), tin (Sn), lead (Pb), aluminum (Al), indium (In), zinc (Zn), hydrogen (H), calcium (Ca), strontium (Sr), Barium (Ba), Ruthenium (Ru), Rhodium (Rh), Iridium (Ir), Palladium (Pd), Platinum (Pt), Silver (Ag), Gold (Au), Cadmium (Cd), Mercury (Hg), Gallium (Ga), thallium (Tl), carbon (C), nitrogen (N), antimony (Sb), bismuth (Bi), oxygen (O), sulfur (S), selenium (Se), tellurium (Te) , A group of elements alloyed with lithium such as chlorine (Cl) and oxides containing these elements (silicon monoxide (SiO), SiOx (0 <x <2), tin dioxide (SnO ₂ ), SnOx (0 <x < 2), SnSiO _3, etc.) and carbides (silicon carbide (SiC), etc.); Metal materials such as lithium metal; And lithium-transition metal composite oxides such as lithium-titanium composite oxide (lithium titanate: Li ₄ Ti ₅ O ₁₂ ). However, it is not limited to these, The conventionally well-known material used as a negative electrode active material for lithium ion secondary batteries can be used.

As a binder (binder), if it contains at least polyvinylidene fluoride (PVDF), it will not specifically limit, You may use another binder together. As another binder, the following materials are mentioned, for example.

Polyethylene (PE), Polypropylene (PP), Polyethylene terephthalate (PET), Polyethernitrile (PEN), Polyacrylonitrile (PAN), Polyimide (PI), Polyamide (PA), Cellulose, Carboxymethylcellulose (CMC), ethylene-vinyl acetate copolymer, polyvinyl chloride (PVC), styrene butadiene rubber (SBR), isoprene rubber, butadiene rubber, ethylene propylene rubber, ethylene propylene diene copolymer, styrene butadiene styrene Thermoplastic polymers, such as a block copolymer and its hydrogenated substance, a styrene isoprene styrene block copolymer, and its hydrogenated substance, polytetrafluoroethylene (PTFE), tetrafluoroethylene hexafluoropropylene copolymer (FEP), tetra Fluoroethylene perfluoroalkyl vinyl ether copolymer (PFA), ethylene tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), Fluorine resins, such as a ethylene chloro trifluoroethylene copolymer (ECTFE) and polyvinyl fluoride (PVF), vinylidene fluoride- hexafluoropropylene type fluorine rubber (VDF-HFP type fluorine rubber), and vinylidene fluoride- Hexafluoropropylene-tetrafluoroethylene fluorine rubber (VDF-HFP-TFE fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-penta Fluoropropylene-tetrafluoroethylene-based fluororubbers (VDF-PFP-TFE-based fluororubbers), vinylidene fluoride-perfluoromethylvinylether-tetrafluoroethylene-based fluororubbers (VDF-PFMVE-TFE-based fluororubbers) And vinylidene fluoride-based fluorine rubbers such as vinylidene fluoride-chlorotrifluoroethylene-based fluorine rubber (VDF-CTFE-based fluorine rubber) and epoxy resins. Especially, it is preferable to use polyvinylidene fluoride independently, and as a binder other than being used together, polyimide, styrene butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, Polyamide is preferred. These suitable binders are excellent in heat resistance, have a very large potential window, are stable to the negative electrode potential, and can be used for the negative electrode active material layer.

However, it is not limited to these, The well-known material conventionally used as a binder for lithium ion secondary batteries can be used together.

Although content of the binder in a negative electrode active material layer will not be specifically limited if it is an quantity which can bind a negative electrode active material, Preferably it is 0.5-15 mass% with respect to a negative electrode active material layer, More preferably, it is 1-10. It is mass%.

A conductive support agent is mix | blended in order to improve the electroconductivity of a negative electrode active material layer. As a conductive support agent, carbon materials, such as carbon black, such as acetylene black, graphite, and vapor-grown carbon fiber, are mentioned, for example. When a negative electrode active material layer contains a conductive support agent, the electronic network in the inside of a negative electrode active material layer can be formed effectively, and can contribute to the improvement of the output characteristic of a battery.

However, it is not limited to these, The conventionally well-known material used as a conductive support agent for lithium ion secondary batteries can be used. These electrically conductive adjuvant may be used individually by 1 type, and may use 2 or more types together.

Moreover, you may use the conductive binder which has the function of the said conductive support agent and a binder instead of these conductive support agents. As the conductive binder, for example, TAB-2 (manufactured by Hosen Industries, Ltd.) which is already commercially available can be used.

In addition, the thickness of each active material layer (active material layer on one side of the current collector) is not particularly limited, and conventionally known knowledge regarding batteries can be appropriately referred to. For example, the thickness of each active material layer is usually about 1 to 500 µm, preferably 2 to 100 µm, in consideration of the purpose of use of the battery (output importance, energy importance, etc.) and ion conductivity.

In addition, when the optimum particle diameter differs in expressing the effect unique to each active material, what is necessary is just to mix and use the optimal particle diameters in order to express each unique effect, and it is necessary to make the particle size of all active materials uniform. There is no.

For example, when using the oxide in particle form as a positive electrode active material, the average particle diameter of an oxide should just be about the same as the average particle diameter of the positive electrode active material contained in the existing positive electrode active material layer, and is not specifically limited. From the viewpoint of high output, it is preferably in the range of 1 to 20 mu m. In the present specification, the "particle diameter" means a distance between arbitrary two points on the contour line of the active material particle (observation plane) observed using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) The maximum distance between the two. As the value of the &quot; average particle diameter &quot;, a value calculated as an average value of the particle diameters observed in several to several tens of fields is adopted by using observation means such as a scanning electron microscope (SEM) or a transmission electron microscope . The particle diameters and average particle diameters of the other constituents can be similarly defined.

However, it is not restrict | limited to this range at all, It goes without saying that if it is possible to express the effect of this embodiment effectively, you may leave this range.

As the electrolyte layer 13, the layer structure formed using the electrolyte solution and the polymer gel electrolyte hold | maintained in the separator mentioned later in detail, etc. are mentioned, for example.

As electrolyte solution, it is preferable to be used normally, for example in a lithium ion secondary battery, and it has the form which the support salt (lithium salt) melt | dissolved in the organic solvent specifically ,. Examples of lithium salts include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiAsF ₆ ), and lithium hexafluorophosphate (LiTaF ₆ ). , Inorganic acid anion salts such as lithium tetrachloride aluminum (LiAlCl ₄ ), lithium decachlorodecaboic acid (Li ₂ B ₁₀ Cl ₁₀ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium bis (trifluoromethane Selected from organic acid anion salts such as sulfonyl) imide (Li (CF ₃ SO ₂ ) ₂ N), lithium bis (pentafluoroethanesulfonyl) imide (Li (C ₂ F ₅ SO ₂ ) ₂ N) And at least one kind of lithium salt. Moreover, as an organic solvent, For example, cyclic carbonates, such as propylene carbonate (PC) and ethylene carbonate (EC); Chain carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate (EMC) and diethyl carbonate (DEC); Ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane and 1,2-dibutoxyethane; lactones such as γ-butyrolactone; Nitriles such as acetonitrile; Esters such as methyl propionate; Amides such as dimethylformamide; The thing using organic solvents, such as an aprotic solvent which mixed at least 1 sort (s) or 2 or more types chosen from methyl acetate and methyl formate, etc. can be used. Moreover, as a separator, the microporous membrane which consists of polyolefins, such as polyethylene (PE) and a polypropylene (PP), a porous flat plate, and a nonwoven fabric are mentioned, for example.

As a polymer gel electrolyte, what contains the polymer and electrolyte solution which comprise a polymer gel electrolyte in a conventionally well-known ratio are mentioned. For example, it is preferable to set it as about several mass%-about 98 mass% from a viewpoint of ion conductivity.

The polymer gel electrolyte contains a solid polymer electrolyte having ionic conductivity as described above, which is usually used in lithium ion secondary batteries. However, it is not limited to this, The thing which maintained the same electrolyte solution in the skeleton of the polymer which does not have lithium ion conductivity is also included. Examples of the polymer having no lithium ion conductivity used in the polymer gel electrolyte include polyvinylidene fluoride (PVdF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and the like. Can be used. However, it is not limited to these. In addition, since polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), etc., if any of them enters the class which has little ion conductivity, it can also be set as the polymer which has the said ion conductivity, but here, It is illustrated as a polymer which does not have lithium ion conductivity used for a gel electrolyte.

The thickness of the electrolyte layer is preferably thinner from the viewpoint of reducing the internal resistance. The thickness of an electrolyte layer is 1-100 micrometers normally, Preferably it is 5-50 micrometers.

In addition, the matrix polymer of the polymer gel electrolyte can express excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, what is necessary is just to perform superposition | polymerization processes, such as thermal polymerization, an ultraviolet polymerization, a radiation polymerization, an electron beam polymerization, with respect to a polymeric polymer using a suitable polymerization initiator.

Next, the manufacturing method of the lithium ion secondary battery using this electrode of the lithium ion secondary battery of this embodiment mentioned above is explained in full detail with some examples.

First, a positive electrode is produced. For example, when using a granular positive electrode active material, a positive electrode active material, polyvinylidene fluoride, a solvent, a conductive support agent, and another binder are mixed as needed, and a slurry for positive electrode formation is obtained (process 1). In this step, since polyvinylidene fluoride is dissolved in a solvent such as N-methylpyrrolidone (NMP), the crystallinity is lowered to some extent regardless of the initial crystallinity of the polyvinylidene fluoride.

Subsequently, this positive electrode forming slurry is applied to a positive electrode current collector and dried to obtain a positive electrode precursor (step 2). In this step, for example, in order to suppress segregation such as polyvinylidene fluoride and a conductive aid during drying, a set temperature in a hot air drying furnace for evaporating a solvent such as N-methylpyrrolidone (NMP). It is necessary to make 100 degreeC or more and 140 degrees C or less. In addition, from the viewpoint of securing the productivity, the residence time in the hot air drying furnace needs to be within 5 minutes.

In addition, this positive electrode precursor is compression molded (step 3). In this step, the same positive electrode as in the prior art can be obtained, but the heat history (total calories, temperature) necessary for the high crystal phase to sufficiently grow in the recrystallization process of polyvinylidene fluoride is insufficient.

Thereafter, the electrode precursor subjected to compression molding is heat treated to obtain a positive electrode (step 4). In this step, for example, it is necessary to perform a heat treatment for exposing to a temperature of 110 ° C. or more and 140 ° C. or less near the melting point of the polyvinylidene fluoride using heating means such as an infrared heater. When such heat treatment is performed, the crystallinity of the polyvinylidene fluoride is further improved. When an infrared heater is used, since it can heat efficiently to the inside of an active material layer, heat processing time can be shortened and it is excellent in productivity. If the polyvinylidene fluoride is not promoted at 100 ° C. or lower, and if it exceeds 140 ° C., the polyvinylidene fluoride moves (moves from the surface layer to the lower layer by melting), thereby changing the electrode physical properties (electrode resistance increases). do.

In addition, a negative electrode is produced. For example, when using a granular negative electrode active material, a negative electrode active material, a polyvinylidene fluoride, a solvent, a conductive support agent, and another binder (binder) are mixed as needed, and a slurry for negative electrode formation is obtained (step 1 '). . Also in this process, since polyvinylidene fluoride is melt | dissolved in solvents, such as N-methylpyrrolidone (NMP), crystallinity falls to some extent regardless of the initial crystallinity of polyvinylidene fluoride.

Subsequently, this negative electrode forming slurry is applied to a negative electrode current collector and dried to obtain a negative electrode precursor (step 2 '). In this step, for example, in order to suppress segregation such as polyvinylidene fluoride and a conductive aid during drying, a set temperature in a hot air drying furnace for evaporating a solvent such as N-methylpyrrolidone (NMP). It is necessary to make 100 degreeC or more and 140 degrees C or less. In addition, from the viewpoint of securing the productivity, the residence time in the hot air drying furnace needs to be within 5 minutes.

Then, this negative electrode precursor is heat compression molded to obtain a negative electrode (step 3 '). In this process, it is preferable to expose to the temperature of 110 degreeC or more and 140 degrees C or less of melting | fusing point of polyvinylidene fluoride, for example, and to pressurize. Crystallization is accelerated by pressurization, and a high crystalline phase can be grown in a shorter time, and the productivity is excellent. Specifically, it is good to pressurize with the roller made 110 degreeC or more and 140 degrees C or less.

In addition, (step 1 ')-(step 3') may be applied instead of (step 1)-(step 4) at the time of preparation of the said positive electrode, and (step 1 ')-at the time of preparation of the said negative electrode Instead of (step 3 '), (step 1) to (step 4) may be applied.

Subsequently, while providing a positive electrode lead to a positive electrode and providing a negative electrode lead to a negative electrode, a positive electrode, a separator, and a negative electrode are laminated | stacked. In addition, the laminated body is sandwiched by a polymer-metal composite laminate sheet, and the outer peripheral part except one side is heat-sealed to obtain a bag-shaped exterior body.

Then, a nonaqueous electrolyte solution containing a lithium salt such as lithium hexafluorophosphate and an organic solvent such as ethylene carbonate is prepared, injected into the inside of the exterior body, and the opening of the exterior body is sealed by heat sealing. Thereby, a laminated lithium ion secondary battery is completed.

<Examples>

Hereinafter, an Example and a comparative example demonstrate this invention further in detail. Specifically, operation as described in each of the following examples was performed, and the laminated type lithium ion secondary battery as shown in FIG. 1 was produced, and the performance was evaluated.

(Example 1-1)

<The composition of the slurry for positive electrode formation>

 Positive electrode active material: lithium manganate (100 parts by weight)

 Binder: Polyvinylidene fluoride (PVDF) (3.0 parts by weight)

 Challenge aid: flaky graphite (1.0 parts by weight), acetylene black (3.0 parts by weight)

 Solvent: N-methylpyrrolidone (NMP) (65 parts by weight)

<Production of Slurry for Positive Electrode Formation>

The slurry for positive electrode formation of the said composition was manufactured as follows. First, 3.0 weight part of binders were melt | dissolved in NMP30 weight part, and the binder solution was produced. Subsequently, 33.0 parts by weight of the binder solution was added to a mixture of 4.0 parts by weight of the conductive aid and 100 parts by weight of lithium manganate, and kneaded with a planetary mixer (manufactured by Asada Deco, PVM100). NMP35 weight part was added, and it was set as the slurry for positive electrode formation (solid content concentration 62weight%).

<Application and drying of slurry for positive electrode formation>

The slurry for positive electrode formation was apply | coated to the single side | surface of an electrical power collector by the die coater, running the electrical power collector which consists of 20 micrometers thick aluminum foil at the traveling speed of 1 m / min. Subsequently, the electrical power collector which apply | coated this positive electrode forming slurry was dried with a hot air drying furnace (drying temperature: 100 degreeC-110 degreeC, drying time: 3 minutes), and 0.02 mass of NMP amount remaining in a positive electrode active material layer is carried out. It was made into% or less.

Moreover, it applied and dried also to the back surface of aluminum foil, and formed the sheet-like positive electrode which has a positive electrode active material layer on both surfaces.

(Press of electrode)

The sheet-shaped electrode was compression-molded by applying a roller press, and cut | disconnected, and the positive electrode of about 25 mg / cm <2>, thickness of about 100 micrometers, and density 3.0g / cm <3> of a single-side active material layer was produced (hereinafter, it is called "positive electrode C1"). There is). When the surface of the positive electrode C1 was observed, no crack was observed.

<Heat treatment of positive electrode C1>

Subsequently, heat processing was performed in the vacuum drying furnace using the positive electrode C1 produced by the said procedure. After the positive electrode C1 was installed inside the drying furnace, the pressure was reduced (100 mmHg (1.33 × 10 ⁴ Pa)) at room temperature (25 ° C.) to remove the air in the drying furnace. Subsequently, it heated up to 120 degreeC at 10 degreeC / min, flowing nitrogen gas (100 cm <3> / min), and it pressure-reduced again at 120 degreeC, hold | maintained for 12 hours, leaving nitrogen in a furnace, and it cooled to room temperature. In this way, the positive electrode of the present example was obtained (hereinafter, referred to as "positive electrode C11").

About the positive electrode C11 obtained in Example 1-1, the peak intensity of Raman shift was measured using the brown rice laser Raman spectroscopy apparatus (LabRAM ARAMIS made from Horiba Corporation). The obtained result is shown in FIG. In addition, about the vertical axis | shaft, the Raman scattering intensity was made into the scattering relative intensity obtained by normalizing the count number 300 to 1.0 and the count number 240 to 0.0.

(Example 1-2)

<The composition of the slurry for positive electrode formation>

 Positive electrode active material: lithium manganate (80 parts by weight), lithium nickelate (20 parts by weight)

 Binder: Polyvinylidene fluoride (PVDF) (3.0 parts by weight)

 Challenge aid: flaky graphite (1.0 parts by weight), acetylene black (3.0 parts by weight)

 Solvent: N-methylpyrrolidone (NMP) (65 parts by weight)

<Production of Slurry for Positive Electrode Formation>

The slurry for positive electrode formation of the said composition was manufactured according to Example 1.

<Application and drying of slurry for positive electrode formation>

According to Example 1-1, the positive electrode slurry of the said composition was apply | coated to the single side | surface of the electrical power collector which consists of aluminum foil of 20 micrometers thickness, and was dried. Moreover, it applied and dried also to the back surface of aluminum foil, and formed the sheet-like positive electrode which has a positive electrode active material layer on both surfaces.

<Press of electrode>

According to Example 1-1, the sheet-shaped electrode was compression molded by applying a roller press and cut, and a positive electrode having a weight of about 25 mg / cm 2, a thickness of about 100 μm, and a density of 3.0 g / cm 3 of a single-sided active material layer was produced. (Hereinafter, it may be referred to as "positive electrode C2").

<Heat treatment of positive electrode C2>

The said positive electrode C2 was heat-processed according to Example 1-1, and the positive electrode of this example was obtained (Hereinafter, it may be called "positive electrode C22.").

(Example 1-3)

According to Example 1-1, the sheet-like positive electrode which has a positive electrode active material layer on both surfaces was formed. Instead of the press and heat treatment of the positive electrode of Example 1-1, the sheet-shaped positive electrode was subjected to heat compression molding by applying a roller press heated to a roller surface temperature of 135 ° C, and cut to cut to about 25 mg / weight of the active material layer on one side. The positive electrode of this example of cm <2>, about 100 micrometers in thickness, and a density of 3.0 g / cm <3> was produced (it may be called "positive electrode C33" hereafter). When the surface of positive electrode C33 was observed, no crack was observed.

About the positive electrode C33 obtained in Example 1-3, the peak intensity of Raman shift was measured using the brown rice laser Raman spectroscopy apparatus (LabRAM ARAMIS made from Horiba Corporation). The obtained result is shown in FIG.

(Examples 1-4)

According to Example 1-1, the sheet-like positive electrode which has a positive electrode active material layer on both surfaces was formed. Instead of Example 1-1 (heat treatment of positive electrode C1), heat processing was performed by the infrared heating furnace. Output was adjusted so that the surface temperature of a sheet-like positive electrode might be 130 degreeC-140 degreeC, flowing nitrogen in an infrared heating furnace, and it ran at 0.5 m / min (heating processing time: 6 minutes), and obtained the positive electrode (" May be referred to as positive electrode C4).

Subsequently, in accordance with Example 1-1, the sheet-shaped positive electrode was subjected to compression molding by applying a roller press, cut, and cut into pieces having a weight of about 25 mg / cm 2, a thickness of about 100 μm, and a density of 3.0 g / cm 3 of the active material layer on one side. The positive electrode of the example was produced (it may be called "positive electrode C44" hereafter).

(Example 1-5)

<The composition of the slurry for negative electrode formation>

 Negative electrode active material: natural graphite (100 parts by weight)

 Binder: Polyvinylidene fluoride (PVDF) (5.0 parts by weight)

 Challenge Aid: Acetylene Black (1.0 parts by weight)

 Solvent: N-methylpyrrolidone (NMP) (97 parts by weight)

<Production of Slurry for Negative Electrode Formation>

The slurry for negative electrode formation of the said composition was manufactured as follows. First, 5.0 parts by weight of the binder was dissolved in 50 parts by weight of NMP to prepare a binder solution. Subsequently, 55.0 weight part of said binder solutions are added to 1.0 weight part of electrically conductive adjuvant, and 100 weight part of natural graphite powders, and it knead | mixes with a planetary mixer (Asada de Co., PVM100), Then, it mixes with NMP47. A weight part was added to make a slurry for negative electrodes (52 weight% of solid content concentration).

<Application and drying of slurry for negative electrode>

The slurry for negative electrode formation was apply | coated to the single side | surface of an electrical power collector by the die coater, running the current collector which consists of 10 micrometers thick electrolytic copper foil at the traveling speed of 1.5 m / min. Subsequently, the current collector coated with the negative electrode forming slurry was dried by a hot air drying furnace (drying temperature: 100 ° C to 110 ° C, drying time: 2 minutes), and the amount of NMP remaining in the negative electrode active material layer was 0.02 mass. It was made into% or less.

In addition, application | coating and drying were performed also to the back surface of an electrical power collector similar to the above, and the sheet-like negative electrode which has a negative electrode active material layer on both surfaces was formed.

<Negative press>

The sheet-shaped negative electrode was subjected to compression molding by applying a roller press, and cut to obtain a negative electrode having a weight of about 10 mg / cm 2, a thickness of about 50 μm, and a density of 1.45 g / cm 3 of a single-sided active material layer (hereinafter, referred to as “negative electrode A1”). have). When the surface of the negative electrode A1 was observed, no crack was observed.

<Heat Treatment of Negative Electrode A1>

Subsequently, heat processing was performed in the vacuum drying furnace using the negative electrode A1 produced by the said procedure. After the negative electrode A1 was installed inside the drying furnace, it was decompressed (100 mmHg (1.33 × 10 ⁴ Pa)) at room temperature (25 ° C.) to remove the air in the drying furnace. Subsequently, it heated up to 135 degreeC at 10 degreeC / min, flowing nitrogen gas (100 cm <3> / min), and it pressure-reduced again at 135 degreeC, hold | maintained for 12 hours while exhausting nitrogen in a furnace, and it cooled to room temperature. In this way, the negative electrode of this example was obtained (hereinafter, referred to as "negative electrode A11").

About the negative electrode A11 obtained in Example 1-5, the peak intensity of Raman shift was measured using the brown rice laser Raman spectroscopy apparatus (LabRAM ARAMIS made from Horiba, Ltd.). The obtained result is shown in FIG.

(Examples 1-6)

<The composition of the slurry for negative electrode formation>

 Negative Electrode Active Material: Artificial Graphite (100 parts by weight)

 Binder: Polyvinylidene fluoride (PVDF) (6.5 parts by weight)

 Challenge Aid: Acetylene Black (1.1 parts by weight)

 Additive: Oxalic anhydride (0.06 parts by weight)

 Solvent: N-methylpyrrolidone (NMP) (99 parts by weight)

<Application and drying of slurry for negative electrode formation>

According to Example 1-5, the slurry for negative electrode formation of the said composition was apply | coated to one side of the electrical power collector which consists of 10-micrometer-thick electrolytic copper foil, and it dried.

In addition, application | coating and drying were performed also to the back surface of an electrical power collector similar to the above, and the sheet-like negative electrode which has a negative electrode active material layer on both surfaces was formed.

<Negative press>

According to Example 1-5, the sheet-shaped negative electrode was subjected to compression molding by applying a roller press, and cut to form a negative electrode having a weight of about 10 mg / cm 2, a thickness of about 50 μm, and a density of 1.45 g / cm 3 of a single-sided active material layer. (Hereinafter, it may be referred to as "negative electrode A2"). When the surface of the negative electrode A2 was observed, no crack was observed.

<Heat treatment of negative electrode A2>

Subsequently, heat processing was performed in the vacuum drying furnace using the negative electrode A2 produced by the said procedure. After the negative electrode A2 was installed inside the drying furnace, the pressure in the drying furnace was removed at a room temperature (25 ° C) under reduced pressure (100 mmHg (1.33 x 10 ⁴ Pa)). Subsequently, it heated up to 135 degreeC at 10 degreeC / min, flowing nitrogen gas (100 cm <3> / min), and it pressure-reduced again at 135 degreeC, hold | maintained for 12 hours while exhausting nitrogen in a furnace, and it cooled to room temperature. In this way, the negative electrode of this example was obtained (hereinafter, referred to as "negative electrode A22").

(Example 1-7)

According to Example 1-5, the sheet-like negative electrode which has a negative electrode active material layer on both surfaces was formed. Instead of the press and heat treatment of the negative electrode 1 of Example 1-5, the sheet-shaped negative electrode was subjected to heat compression molding by applying a roller press heated to a roller surface temperature of 120 ° C, and cut to cut the weight of the active material layer on one side. A negative electrode of the present example (hereinafter referred to as "negative electrode A33") of about 10 mg / cm 2, thickness of about 50 μm, and density of 1.45 g / cm 3 was produced. When the surface of the negative electrode A33 was observed, no crack was observed.

About the negative electrode A33 obtained in Example 1-7, the peak intensity of Raman shift was measured using the brown rice laser Raman spectroscopy apparatus (LabRAM ARAMIS made from Horiba, Ltd.). The obtained result is shown in FIG.

(Examples 1-8)

According to Example 1-5, the sheet-like negative electrode which has a negative electrode active material layer on both surfaces was formed. Instead of Example 1-5 (heat treatment of the negative electrode 1), heat treatment was performed in an infrared heating furnace. The output was adjusted so that the surface temperature of a sheet-like negative electrode might be 130 degreeC-140 degreeC, flowing nitrogen in an infrared heating furnace, and it ran at 0.2 m / min (heating processing time: 15 minutes), and obtained negative electrode A4. Subsequently, in accordance with Example 5, the sheet-shaped negative electrode was subjected to compression molding by applying a roller press, cut, and cut to form a negative electrode of this example having a weight of about 10 mg / cm 2, a thickness of about 50 μm, and a density of 1.45 g / cm 3 of a single-side active material layer. (Hereinafter, referred to as "negative electrode A44") was produced.

(Comparative Example 1-1)

According to Example 1-1, the sheet-shaped positive electrode which has a positive electrode active material layer was formed on both surfaces, and this sheet-like positive electrode was compression-molded by cutting with a roller press, and cut | disconnected, and the weight of the single-sided active material layer is about 25 mg / A positive electrode C1 having a cm 2, a thickness of about 100 μm, and a density of 3.0 g / cm 3 was produced. It was used as a positive electrode of this example as it is without performing subsequent heat processing.

About the positive electrode C1 obtained by the comparative example 1-1, the peak intensity of Raman shift was measured using the brown rice laser Raman spectroscopy apparatus (LabRAM ARAMIS made from Horiba Corporation). The obtained result is shown in FIG.

(Comparative Example 1-2)

According to Example 1-5, the sheet-shaped negative electrode which has a negative electrode active material layer on both surfaces is formed, and this sheet-shaped negative electrode is compression-molded by cutting with a roller press, and it cut | disconnects and weighs about 10 mg / of the active material layer of a single side | surface. Negative electrode A1 of cm <2>, about 50 micrometers in thickness, and a density of 1.45 g / cm <3> was produced. It was used as a negative electrode of this example as it is without performing subsequent heat processing. About the negative electrode A1 obtained by the comparative example 1-2, the peak intensity of Raman shift was measured using the brown rice laser Raman spectroscopy apparatus (LabRAM ARAMIS made from Horiba, Ltd.). The obtained result is shown in FIG.

Table 1 shows a part of the specifications of the positive electrode or the negative electrode in each of the above examples.

In addition, V2 / (V1 + V2) took the test piece from the active material layer of the positive electrode or negative electrode of each case, and measured the Raman shift using the brown rice laser Raman spectroscopy apparatus (LabRAM ARAMIS, Inc.). It calculated from the peak intensity of In the range from 3500 cm ^-1 to 500 cm ^-1 , the Raman shift derived from PVDF has a large fluctuation in the baseline due to the rise of the background, so the peak intensities of V1 and V2 are as shown in Figs. Similarly, it determined by subtracting the background to 3500 cm <^-1> -500 cm <^-1> .

[Evaluation of Electrode]

(Measurement of electrode thickness)

About the electrode (positive electrode or negative electrode) of each said example, the thickness of ten points in a test piece (electrode active material layer part) was measured using the micrometer before the following swelling process. Moreover, after swelling process, thickness was measured again. The increase rate of the thickness before and after a swelling process was computed. The obtained results are written together in Table 1.

<Swelling treatment>

The electrode of each said example was put into the aluminum laminate pack containing 20 cm <3> of mixed solutions of ethylene carbonate (EC) and diethyl carbonate (DEC), and the opening part was thermocompression-sealed. This laminate pack was put into a thermostat (85 degreeC), and it hold | maintained for 48 hours. After 48 hours, the laminate pack was taken out from the thermostat, one side was opened, and the electrode was taken out. The taken-out electrode was wash | cleaned 5 times with ethanol, and it dried at 40 degreeC for 2 hours.

(Measurement of electrode resistance)

Prior to the above swelling treatment, the resistance of 10 points in the test piece (electrode active material layer portion) was measured using a simple low-resistance meter (trade name; Lorestar MCP-T370 (Mitsubishi Chemical Corporation)). Moreover, after swelling process, resistance was measured again. The increase rate of resistance before and after a swelling process was computed. The obtained results are written together in Table 1.

From Table 1, Examples 1-1 to 1-8 belonging to the scope of the present invention have a reduced thickness increase rate and a higher resistance increase rate than Comparative Examples 1-1 and Comparative Example 1-2 other than the present invention. It can be seen that. In addition, when V2 / (V1 + V2) is set to 0.70 or more as in Example 1-3, Example 1-4, Example 1-7, and Example 1-8, the thickness increase rate and the resistance increase rate are further reduced. okay.

In addition, V2 / (V1 + V2) in the case of not heating at all is about 0.3 or more and about 0.4 or less.

(Example 2-1)

<Fabrication of Battery>

The lead was welded to the collector part of negative electrode A11 (active material layer area length: 3.8 cm x width: 5.5 cm), and positive electrode C11 (active material layer area length: 3.6 cm x width: 5.3 cm). Laminated type consisting of five layers between a porous polypropylene separator S (4.5 cm in length x 6.0 cm in width, 25 µm in thickness and 55% porosity) between the negative electrode A11 and the positive electrode C11 on which these leads are welded (lamination example) , An electrode structure of A11- (S) -C11- (S) -A11) was produced. Subsequently, both sides were sandwiched by an aluminum laminate film (5.0 cm x 6.5 cm), and the three sides were thermocompression-sealed to accommodate the electrode structure. Into this electrode structure, 0.5 cm 3 / cell of a mixed solution of ethylene carbonate (EC) and diethyl carbonate (DEC) in which 1.0 mol / liter of LiPF ₆ was dissolved as an electrolyte was injected. It was thermocompression-sealed and the laminated lithium ion secondary battery of this example was produced. A part of the specification of this example is shown in Table 2.

(Example 2-2 to Example 2-14 and Comparative Example 2-1)

Except having used the negative electrode and positive electrode shown in Table 1, operation similar to Example 2-1 was repeated and the laminated type lithium ion secondary battery of each example was produced.

[Evaluation of Battery Performance]

(Measurement of battery capacity and DC resistance)

About the lithium ion secondary battery of said each case, 200 cycles were repeated at 55 degreeC for charging / discharging by the following 1.0 Crate. Then, I-V measurement was performed at room temperature, and the capacity retention rate and direct current resistance (DCR) rise rate with respect to the 1st cycle were compared. The obtained results are written together in Table 2.

Charge / discharge treatment

Charging is performed by a constant current constant voltage charging method that is charged at 1.0 C rate until the maximum voltage reaches 4.2 V, and then held for about 1 hour to 1.5 hours. Discharge is 1.0 until the battery's minimum voltage reaches 2.5 V. It carried out by the constant current discharge method which discharges with a C rate. All were performed at room temperature.

(Measurement of battery thickness)

Before measuring the capacity and direct current resistance of the battery, the thickness of six points (positioned and indicated) in the battery surface was measured using a micrometer. In addition, after measuring the battery capacity and DC resistance, the thickness of the display portion was again measured using a micrometer to calculate the increase rate of the cell thickness before and after the battery capacity and DC resistance measurement. The obtained results are written together in Table 2.

From Table 2, Examples 2-1 to 2-14 belonging to the scope of the present invention have a reduction in capacity retention rate, a thickness increase rate, and a DC resistance increase rate compared with Comparative Example 2-1 other than the present invention. I can see that there is. When Examples 2-1 to 2-12 are compared with Examples 2-13 and 2-14, the application of the electrode of the present invention to both the positive electrode and the negative electrode reduces the capacity retention rate and the thickness. It turned out that the increase rate and the DC resistance rise rate are further reduced. In addition, V2 / (V1 + V2) in the case of not heating at all is about 0.3 or more and about 0.4 or less.

As mentioned above, although this invention was demonstrated by some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the scope of the summary of this invention.

That is, in the said embodiment and Example, although the lithium ion secondary battery was illustrated as an electric device, it is not limited to this, It is applicable also to another type of secondary battery and a primary battery. Moreover, it is applicable to not only a battery but a lithium ion capacitor. That is, the electrode for electrical devices or an electrical device of this invention contains an electrode active material and polyvinylidene fluoride at least, for example, The electrode for electrical devices in which the peak intensity of the Raman shift measured by Raman spectroscopy satisfy | fills a predetermined relationship. Or what is used may be sufficient, and it does not specifically limit about other structural requirements, such as an electrical power collector and an insulating plate.

For example, the present invention can be applied not only to the laminate battery described above, but also to a conventionally known form and structure such as a coin-type battery, a button-type battery, and a can-type battery such as a square or a cylinder.

For example, the present invention can be applied not only to the above-described stacked type (flat type) battery but also to a conventionally known form and structure such as a wound type (cylindrical) battery.

For example, in the present invention, when viewed in the form of electrical connection (electrode structure) in a lithium ion secondary battery, not only the above-described normal type (internal parallel connection type) battery but also a bipolar type (internal series connection type) battery and the like. It is also applicable to a conventionally known form and structure. In addition, a battery element in a bipolar battery generally has a structure in which a negative electrode active material layer is formed on one surface of a current collector, a bipolar electrode in which a positive electrode active material layer is formed on the other surface, and a plurality of electrolyte layers are laminated. have.

1: lithium ion secondary battery
10: battery element
10a: electrode structure
11: positive
11A: positive electrode current collector
11B: positive electrode active material layer
12: negative electrode
12A: negative electrode current collector
12B: negative electrode active material layer
13: electrolyte layer
13a: separator
14: single cell layer
21: positive electrode lead
22: negative electrode lead
30: exterior

Claims (10)

An electrode for an electrical device containing at least an electrode active material and polyvinylidene fluoride,
The peak intensity of Raman shift measured by Raman spectroscopy of the electrode for electrical device is represented by
&Quot; (1) &quot;

(Equation 1, V1 is the integral value of the peak intensity of the Raman shift peak band (3000 cm ^-1 to 2000 cm ^-1 ) of low crystalline polyvinylidene fluoride in the electrode, and V2 is high crystallinity in the electrode. An electric device electrode characterized by satisfying a relationship between a Raman shift peak band of polyvinylidene fluoride (showing an integral value of peak intensities of 2000 cm ^-1 to 1000 cm ^-1 ). The electrode on the side of Claim 1 whose right side in said Formula (1) is 0.70. Positive electrode for electrical devices,
A negative electrode for an electrical device,
A separator located between them,
At least one of the said positive electrode for electrical devices and the said negative electrode for electrical devices is made into the electrode for electrical devices of Claim 1 or 2, The electrode structure for electrical devices characterized by the above-mentioned. Positive electrode for electrical devices,
A negative electrode for an electrical device,
A separator located between them,
Both the positive electrode for an electric device and the negative electrode for an electric device are used as the electrode for an electric device according to claim 1 or 2, wherein the electrode structure for an electric device. Positive electrode for electrical devices,
A negative electrode for an electrical device,
A separator located between them,
Both the positive electrode for an electric device and the negative electrode for an electric device are used as the electrode for an electric device according to claim 1, wherein the electrode structure for an electric device. The electrode structure according to claim 5, wherein the negative electrode for the electric device satisfies V2 / (V1 + V2) ≧ 0.60. The electrode structure for electric devices of Claim 3,
With non-aqueous electrolyte,
An electrical device, comprising: an exterior that accommodates them. 8. The electrical device of claim 7, wherein the electrical device is a secondary battery or a capacitor. It is a method of manufacturing the electrode for electric devices of Claim 1, Comprising: (Step 1)-(Step 4)
(Process 1): the process of obtaining the slurry for electrode formation containing an electrode active material, polyvinylidene fluoride, and a solvent at least,
(Step 2): step of drying the electrode forming slurry to obtain an electrode precursor,
(Step 3): a step of compression molding the electrode precursor,
(Process 4): The manufacturing method of the electrode for electric devices characterized by including the process of heat-processing the said compression molded electrode precursor, and obtaining an electrode. The method for manufacturing an electrode for an electric device according to claim 9, wherein the compression molding of (step 3) and the heat treatment of (step 4) are performed at the same time.

Images