JP2009252497A - Electrode for battery and battery - Google Patents

Abstract

A means for improving the operability of a secondary battery even in a low temperature environment is provided.
At least one first active material layer including a first active material and at least one second active material layer including a second active material having an electric resistance higher than that of the first active material. And the second active material layer includes a battery electrode disposed on the outside in the area direction from at least one layer of the first active material layer, and a first single battery layer including the first active material, And a second unit cell layer containing a second active material having a higher electric resistance than the first active material, wherein the second unit cell layer is laminated from at least one layer of the first unit cell layer. It is a battery arranged on the outside in the direction.
[Selection] Figure 1

Description

  The present invention relates to a battery electrode and a battery. More specifically, the present invention relates to a battery electrode that improves the operability of a secondary battery even in a low-temperature environment, and a battery with improved low-temperature operability.

  In recent years, in order to cope with air pollution and global warming, reduction of the amount of carbon dioxide has been strongly desired. In the automobile industry, there is a great expectation for reducing carbon dioxide emissions by introducing electric vehicles (EV) and hybrid electric vehicles (HEV), and the development of secondary batteries for motor drive that holds the key to commercialization of these is thriving. Has been done.

  As a secondary battery for driving a motor, a lithium ion secondary battery having the highest theoretical energy among all the batteries is attracting attention, and is currently being developed rapidly. Generally, a lithium ion secondary battery includes a positive electrode in which a positive electrode active material or the like is applied to both surfaces of a positive electrode current collector using a binder, and a negative electrode in which a negative electrode active material or the like is applied to both surfaces of a negative electrode current collector using a binder. However, it has the structure connected through an electrolyte layer and accommodated in a battery case.

Many materials have been proposed and studied as positive and negative electrode active materials for lithium ion secondary batteries. For example, Patent Document 1 proposes an electrode for a secondary battery that is applied to thermal stress due to high voltage and large current discharge required in a cold region by alternately arranging materials that relieve thermal stress. .
JP 2005-11660 A

  However, although the technique described in Patent Document 1 can suppress the deterioration of stress due to the heat of the battery and improve the durability, the low temperature startability of the battery in a cold region or the like is not sufficient.

  Therefore, an object of the present invention is to provide means for improving the operability of a secondary battery even in a low temperature environment.

  In light of the above problems, the present inventors have conducted extensive research and as a result, an electrode including a layer containing an active material having a low electrical resistance value and a layer containing an active material having a high electrical resistance value was generated by discharge. It was found that heat was released efficiently. At that time, a layer including an active material having a low electrical resistance value is disposed inside the electrode in the area direction, and an electrode including the layer including an active material having a high electrical resistance value in the area direction of the electrode generates heat generated by discharge. It was found that the battery was efficiently released and the low temperature operability of the battery was improved.

  That is, the present invention provides at least one first active material layer including a first active material and at least one second active material including a second active material having an electric resistance higher than that of the first active material. The battery electrode is composed of a material layer, and the second active material layer is arranged outside in the area direction from at least one of the first active material layers.

  Further, the present invention comprises a first unit cell layer including a first active material and a second unit cell layer including a second active material having a higher electric resistance value than the first active material, The second unit cell layer is a battery arranged outside in the stacking direction from at least one layer of the first unit cell layer.

  ADVANTAGE OF THE INVENTION According to this invention, the battery electrode which can improve the low temperature operability of a secondary battery, and the battery which improved low temperature operability can be provided.

  Hereinafter, the present invention will be described in detail.

(Configuration of battery including battery electrode of the present invention)
The present invention provides at least one first active material layer containing a first active material and at least one second active material layer containing a second active material having a higher electrical resistance than the first active material. The second active material layer is a battery electrode disposed outside in the area direction from at least one layer of the first active material layer.

  First, an example of the structure of a battery using the battery electrode of the present invention will be described. The battery electrode of the present invention described here includes, in the positive electrode, a first active material and a second active material having an electric resistance value higher than that of the first active material. In this case, the first active material layer including the first active material is disposed inside the electrode in the area direction, and the second active material layer including the second active material is disposed outside the electrode in the area direction. ing. However, the technical scope of the present invention is not limited to such a form, and only the negative electrode includes the battery electrode of the present invention, or both the positive electrode and the negative electrode include the battery electrode of the present invention. Can also be included.

  The secondary battery according to the present invention is not particularly limited. For example, when distinguished by the structure of the battery, it is not particularly limited, such as a stacked (flat) battery or a wound (cylindrical) battery, and can be applied to any conventionally known structure. It is. Similarly, when distinguishing by the type of electrolyte of the secondary battery, it should not be particularly limited, and the liquid electrolyte type battery, polymer gel electrolyte type battery and solid polymer electrolyte (all solid electrolyte) type battery are not limited. It can be applied to both. These electrolytes can be used alone as these polymer gel electrolytes and solid polymer electrolytes (all solid electrolytes), or electrolytes, polymer gel electrolytes, solid polymer electrolytes (all solid electrolytes) can be used as separators (nonwoven fabrics). Can also be used. Therefore, there is no particular limitation. In addition, when viewed in the electrical connection form (electrode structure) in the battery, it can be applied to both a non-bipolar (internal parallel connection type) battery and a bipolar (internal series connection type) battery. . Furthermore, there is no restriction | limiting in particular about selection of a support salt (lithium salt), an electrolyte, and the compound added as needed, What is necessary is just to select suitably with reference to a conventionally well-known knowledge according to a use application.

  Hereinafter, members constituting the battery electrode of the present invention will be described in detail.

[Current collector]
The current collector is made of a conductive material such as aluminum foil, nickel foil, copper foil, or stainless steel (SUS) foil. The general thickness of the current collector is 1 to 30 μm. However, a current collector having a thickness outside this range may be used.

  The size of the current collector is determined according to the intended use of the battery. If a large electrode used for a large battery is manufactured, a current collector having a large area is used. If a small electrode is produced, a current collector with a small area is used.

[Active material layer]
<Active material>
The battery electrode of the present invention includes an active material layer. The active material layer is a layer containing an active material that plays a central role in the charge / discharge reaction. The battery electrode of the present invention includes a first active material layer containing a first active material, and a second active material layer containing a second active material having an electric resistance higher than that of the first active material. .

  Specific examples of the first active material used in the positive electrode include olivine-type lithium iron phosphate, olivine-type cobalt lithium phosphate, olivine-type lithium manganese phosphate, and lithium titanate.

Specific examples of the second active material used in the positive electrode, for example, lithium, such as LiNiO ₂ - nickel composite oxide, lithium such as LiMn ₂ O ₄ - manganese composite oxide, lithium such as LiCoO ₂ - Examples include cobalt complex oxides.

  Specific examples of the first active material used in the negative electrode include lithium titanate, Si-based alloys, Sn-based alloys, and the like.

  Specific examples of the second active material used in the negative electrode include hard carbon and graphite.

In the present invention, the electric resistance value of the second active material is higher than the electric resistance value of the first active material. If such a relationship between the electrical resistance values is established, the combination of the first active material and the second active material is not particularly limited. However, from the viewpoint of further improving the effect of the present invention, the difference between the second electric resistance value and the first electric resistance value is preferably 10 to 100 mΩcm ² , more preferably 10 to 30 mΩcm ^2. It is preferable to select a combination of active materials such that

  When the first active material and the second active material are positive electrode active materials, it is preferable that an average particle size of the first active material and the second active material is 0.1 to 100 μm. The average particle diameter is more preferably 0.1 to 10 μm, and further preferably 0.1 to 1 μm.

  On the other hand, when the first active material and the second active material are negative electrode active materials, the average particle diameter of the first active material and the second active material may be 0.1 to 100 μm. preferable. The average particle diameter is more preferably 0.1 to 10 μm, and further preferably 0.1 to 1 μm. In the present invention, the average particle diameter is a value of average particle diameter D50 measured by a laser diffraction method.

<Conductive aid>
The active material layer contains a conductive additive. A conductive support agent plays the role which improves the electroconductivity of an active material layer. Examples of the conductive aid include carbon black, flaky graphite, ketjen black, acetylene black, and various carbon fibers such as vapor grown carbon fiber (VGCF; registered trademark).

<Binder>
Further, the active material layer may include a binder. The binder is an additive that plays a role in binding the active material and the conductive additive. The binder is not particularly limited as long as it can bind the active material and the conductive additive. Specific examples include, for example, polyethylene, polypropylene, polyethylene terephthalate, polyacrylonitrile, polyamide, polyimide, cellulose, carboxymethyl cellulose, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene-butadiene rubber, isoprene rubber, butadiene rubber. , Ethylene / propylene rubber, ethylene / propylene / diene copolymer, styrene / butadiene / styrene block copolymer and its hydrogenated product, styrene / isoprene / styrene block copolymer and its hydrogenated polymer, etc. , Ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, 1,3-butylene glycol, polyvinyl alcohol, polyvinyl propinal, polyvinylidene Hydroxyl group-containing compounds such as butyral, polyacrylamide, polyethylene glycol, polypropylene glycol, polybutylene glycol, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), Tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), polyfluoride Fluorine resin such as vinyl fluoride (PVF), vinylidene fluoride-hexafluoropropylene-based fluoro rubber (VDF-HFP-based fluoro rubber), vinylidene fluoride Id-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-HFP-TFE-based fluororubber), vinylidene fluoride-pentafluoropropylene-based fluororubber (VDF-PFP-based fluororubber), vinylidene fluoride-pentafluoropropylene- Tetrafluoroethylene fluororubber (VDF-PFP-TFE fluororubber), vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene fluororubber (VDF-PFMVE-TFE fluororubber), vinylidene fluoride-chlorotrifluoro Examples thereof include vinylidene fluoride-based fluororubber such as ethylene-based fluororubber (VDF-CTFE-based fluororubber). These binders may be used alone or in combination of two or more.

<Disposition of active material layer>
In the battery electrode according to the present invention, a first active material layer containing a first active material having a low electrical resistance value is disposed inside the electrode in the area direction, and the first active material is disposed outside the electrode in the area direction. A second active material layer including a second active material having a higher electrical resistance value is disposed. With this structure, heat generated during large current discharge during operation at a low temperature, for example, −20 to 0 ° C., is efficiently received by the second active material having a high electrical resistance value at a low temperature. A battery that can be passed and has excellent low-temperature operability can be provided. In addition, since the first active material, for example, an iron-based material has excellent heat resistance, it is possible to reduce the influence of deterioration due to heat generated during large current discharge during low-temperature operation. It is also useful from the viewpoint of improving the performance.

  Here, in the present invention, the substrate includes a current collector, an electrolyte layer, a separator, an electrode terminal (tab), an appropriate release film other than battery constituent members, and the like.

  The battery electrode of the present invention includes a positive electrode and a negative electrode, as well as a bipolar electrode. That is, in a battery electrode that is not bipolar, the positive electrode has a structure in which a positive electrode layer is formed on both sides of a base, for example, a current collector, and the negative electrode has a negative electrode layer formed on both sides of the base, for example, a current collector. Structure. On the other hand, a bipolar battery electrode, that is, a bipolar electrode has, for example, a structure in which a positive electrode layer is formed on one surface of a current collector or an electrolyte layer, and a negative electrode layer is formed on the other surface.

  In the present invention, the single cell layer means an electrolyte layer, a positive electrode and a negative electrode sandwiching the electrolyte layer, and is a concept common to both bipolar batteries and non-hyperbolic batteries.

  As a specific form of the battery electrode of the present invention, at least two layers containing active materials having different electric resistance values are continuously formed on the substrate so that heat generated by discharge is dissipated to the outside. And / or a plurality of them arranged at intervals. Thereby, the generated heat can be efficiently radiated to the outside of the electrode.

  The arrangement shape (pattern) of the active material layers in the area direction on the substrate of the first active material layer and the second active material layer may be anything as long as the heat generated by the discharge can be dissipated to the outside. It is not limited. Examples of the arrangement shape include concentric shapes such as concentric circles, concentric elliptical shapes, concentric triangular shapes, concentric quadrangular shapes, concentric pentagonal shapes, concentric hexagonal shapes, concentric square shapes, and concentric rectangular shapes (see FIG. 1). However, it is not limited to these.

  The battery electrode of the present invention may be an electrode provided with at least two of the first active material layer and the second active material layer. In this case, as shown in FIG. 2, it is preferable to arrange the first active material layer on the innermost side in the area direction and to arrange the second active material layer on the outermost side.

  Further, the active materials of the same type may be dispersed appropriately, more preferably, substantially evenly, and even more preferably so as not to localize on the substrate. Examples of this structure include, for example, a structure arranged in an array, that is, a so-called sea-island structure as shown in FIG. 3 (the first active material layer is arranged in an island shape, and the second active material layer is The first active material layer is arranged in a sea shape surrounding the first active material layer).

  The arrangement of the first active material layer and the second active material layer on the substrate is not particularly limited as long as the generated heat can be released. The arrangement of the first active material layer and the second active material layer may be regular or irregular. Further, the regular arrangement does not have to be the entire base, and a regular part and an irregular part may be mixed on the base. Moreover, in the some electrode which comprises a battery, arrangement | positioning of the active material layer of each electrode may be the same, and may differ. If an attempt is made to construct a high-capacity, high-voltage, large-current battery, the electrodes constituting the battery also form tens to hundreds of tens of cell layers. In such a case, the temperature distribution situation and the heat escape are different between near the center of the multi-layered electrode and near the outermost layer, so it is possible to change the arrangement on the substrate for each stacked electrode. This is because it may be optimal for escape.

  Further, in the battery electrode of the present invention, the electric resistance value of the active material contained in the active material layer that is finely divided is arranged so as to change from the central portion on the substrate toward the outer peripheral portion. It may be characterized by that. In other words, by disposing the subdivided active materials having different electrical resistance values in a two-dimensional or one-dimensionally inclined manner, the heat generated by the discharge is transferred from the first active material layer to the second. Heat can be efficiently radiated to the active material layer. At this time, the electric resistance value of the active material may be changed as long as the heat generated in the central portion of the electrode can be changed so as to dissipate to the outer peripheral portion. For example, the electrical resistance value of the active material may be changed so as to decrease two-dimensionally or one-dimensionally in a stepwise manner, continuously, or inclined from the central portion toward the outer peripheral portion. The configuration is not limited at all.

  The ratio of the surface area of the first active material layer and the surface area of the second active material layer is such that the first active material layer and the second active material layer are arranged to release heat generated by the discharge. It should not be restricted in particular. However, from the viewpoint of further improving the effect of the present invention, the ratio of the surface area of the first active material layer to the surface area of the second active material layer is preferably 5: 1 to 1: 5, and 2: 1 More preferably, it is ˜1: 2, and 1: 1 is particularly preferable.

  Hereinafter, specific examples of the arrangement of active materials contained in the battery electrode of the present invention will be described with reference to the drawings. However, the present invention is not limited to these examples.

(First example: Example in which two active material layers are arranged in a concentric rectangular shape)
FIG. 1 is a configuration example in which two active material layers are arranged in a concentric rectangular shape on a substrate as a specific example of the battery electrode of the present invention, and is a plane schematically showing the arrangement of the active material layers. It is the schematic (A of FIG. 1) and the cross-sectional schematic (B of FIG. 1).

  A battery electrode 10 shown in FIG. 1 is a positive electrode, and uses a current collector 11 as a substrate, and a first active material layer including a first positive electrode active material having a low electric resistance value on one surface of the current collector 11. 12 is arranged inside the electrode in the area direction (X-axis-Y-axis plane in FIG. 1). Then, a second active material layer 13 containing a second positive electrode active material having an electric resistance value higher than that of the first positive electrode active material is disposed outside the electrode in the area direction so as to surround the periphery thereof.

  With such an arrangement, heat generated by the discharge can be efficiently released from the first active material layer 12 to the second active material layer 13 (that is, in the direction indicated by the arrow in FIG. 1). Furthermore, the low temperature operability of the battery can be improved. However, in this example, only an example of the effects of the present invention is shown, and the surface area of the first active material layer and the surface area of the second active material layer can be set as appropriate.

(Second example: Example in which two active material layers are alternately arranged in a concentric rectangular shape)
FIG. 2 is a configuration example in which two types of active material layers are alternately and concentrically arranged on a substrate as a specific example of the battery electrode of the present invention, and the arrangement of the active material layers is schematically illustrated. 3 is a schematic plan view (A in FIG. 2) and a schematic cross-sectional view (B in FIG. 2).

  A battery electrode 20 shown in FIG. 2 is a positive electrode, and uses a current collector 21 as a substrate, and a first active material layer including a first positive electrode active material having a low electric resistance value on one surface of the current collector 21. 22 is arranged inside the electrode in the area direction (portion close to the center). Then, toward the outside of the electrode, the first active material layers 22 and the second active material layers 23 containing a second positive electrode active material having an electric resistance higher than that of the first positive electrode active material are alternately and Arrange in a concentric rectangular shape. At this time, the second active material layer 23 containing the second positive electrode active material is disposed on the outermost periphery of the electrode.

  As shown in this example, the first active material layer 22 having a low resistance is disposed inside the electrode, and the first active material layer and the second active material layer having a high resistance are alternately and concentrically rectangular. By setting it as the structure arrange | positioned in, the surface area of a said 1st active material layer increases. With such an arrangement, the heat generated by the discharge can be more efficiently released from the first active material layer 22 to the second active material layer 23 (that is, in the direction indicated by the arrow in FIG. 2). And the low-temperature operability of a battery can be improved. However, in this example, only an example of the effects of the present invention is shown, and the surface area of the first active material layer 22 and the surface area of the second active material layer 23 and the first active material layer 22 The number and the number of the second active material layers 23 may be set as appropriate.

(Third example: Example in which the first active material layer is arranged in an island shape)
FIG. 3 is a configuration example in which the first active material layer 32 is arranged in an island shape on a substrate as a specific example of the battery electrode of the present invention, and is a plan view schematically showing the arrangement of the active material layer. It is the schematic (A of FIG. 3) and the cross-sectional schematic (B of FIG. 3).

  A battery electrode 30 shown in FIG. 3 is a positive electrode, and a current collector 31 is used as a base. A first active material layer 32 containing a first positive electrode active material is formed in an island shape on one surface of the current collector 31. Deploy. Then, the second active material layer 33 containing the second positive electrode active material is disposed so as to surround each of the first active material layers 32, that is, in a sea shape.

  As shown in this example, the first active material layer 32 having a low resistance is arranged in an island shape, and the second active material layer 33 having a high resistance is arranged in a sea shape. The surface area of the one active material layer 32 is further increased. With such an arrangement, the heat generated by the discharge can be efficiently released from the first active material layer 32 to the second active material layer 33 (that is, in the direction indicated by the arrow in FIG. 3). And the low-temperature operability of a battery can be improved. However, in this example, only an example of the effects of the present invention is shown, and the surface area of the first active material layer 32, the surface area of the second active material layer 33, and the first active material layer 32 The number, that is, the number of islands can be set as appropriate.

  FIG. 3 shows an example in which the shape of the surface of the first active material layer 32 is a square shape, but the present invention is not limited to this. Examples of the shape of the surface of the first active material layer include a circular shape, an elliptical shape, a triangular shape, a quadrangular shape, a pentagonal shape, a hexagonal shape, and a rectangular shape. This shape may be the same in the same electrode, or may be different from each other. Moreover, the space | interval of the area direction of a said 1st active material layer may be fixed, and may differ respectively.

  By arranging the first active material layer and the second active material layer as described above, the heat generated inside the electrode due to the discharge can be efficiently released. Moreover, the low temperature operability of the battery is improved as compared with the conventional case where the active material layer is uniformly formed on the entire surface of the current collector.

  The arrangement of the active material layer in the thickness direction of the electrode is not particularly limited, and conventionally known knowledge can be referred to as appropriate.

  The secondary battery according to the present invention is characterized by using the battery electrode of the present invention described above. By using such a battery electrode, heat generated inside the electrode by discharge can be dissipated to the outside of the electrode, and charge / discharge efficiency can be improved. The secondary battery provided with the battery electrode of the present invention is not particularly limited, and the battery electrode of the present invention can be widely applied to various conventionally known secondary batteries.

  In addition, regarding other structural requirements, since the structural requirements of a conventionally known secondary battery can be used as appropriate, a brief description will be given here.

  The active material layer may contain other materials if necessary. For example, a supporting salt (lithium salt), an ion conductive polymer, and the like can be included. When an ion conductive polymer is included, a polymerization initiator for polymerizing the polymer may be included.

Examples of the supporting salt (lithium salt) include Li (C ₂ F ₅ SO ₂ ) ₂ N, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO _{3 and the} like.

  Examples of the ion conductive polymer include polyethylene oxide (PEO) -based and polypropylene oxide (PPO) -based polymers. Here, the polymer may be the same as or different from the ion conductive polymer used in the electrolyte layer of the battery in which the electrode of the present invention is employed, but is preferably the same.

  The polymerization initiator is added to act on the crosslinkable group of the ion conductive polymer to advance the crosslinking reaction. Depending on the external factor for acting as an initiator, it is classified into a photopolymerization initiator, a thermal polymerization initiator and the like. Examples of the polymerization initiator include azobisisobutyronitrile (AIBN), which is a thermal polymerization initiator, and benzyl dimethyl ketal (BDK), which is a photopolymerization initiator.

  The mixing ratio of components other than the active material, the conductive additive, and the binder contained in the active material layer is not particularly limited, and can be adjusted by appropriately referring to known knowledge about the lithium ion secondary battery.

  The thickness of the active material layer is not particularly limited, and conventionally known knowledge about the lithium ion secondary battery can be appropriately referred to. As an example, the thickness of the active material layer is preferably about 10 to 100 μm, and more preferably 20 to 50 μm. If the active material layer is about 10 μm or more, the battery capacity can be sufficiently secured. On the other hand, if the active material layer is about 100 μm or less, it is possible to suppress the occurrence of the problem of an increase in internal resistance due to the difficulty in diffusing lithium ions in the electrode deep part (current collector side).

(Production method)
Then, the manufacturing method of the battery electrode of this invention is demonstrated.

  The battery electrode of the present invention can be manufactured by the following manufacturing method. For example, a slurry containing the first active material is prepared by adding a first active material, a conductive additive, and a binder to the solvent (a process for preparing a slurry containing the first active material). Separately, a slurry containing the second active material is prepared by adding a second active material, a conductive additive, and a binder to the solvent (a process for preparing a slurry containing the second active material). Thereafter, the slurry containing the first active material and the slurry containing the second active material are applied to the surface of the current collector so as to have a desired arrangement, and dried to form a coating film (coating film forming step) ). Subsequently, it can manufacture by pressing the laminated body produced through the said coating-film formation process in the lamination direction (press process). In some cases, an ion conductive polymer is added to the porous slurry, and a polymerization initiator is further added for the purpose of crosslinking the ion conductive polymer. In that case, you may perform a polymerization process simultaneously with the drying in a coating-film formation process, or before or after the said drying (polymerization process).

  Hereinafter, although such a manufacturing method is demonstrated in detail in order of a process, it is not restrict | limited only to the following form.

[Preparation Step of Slurry Containing First Active Material, Preparation Step of Slurry Containing Second Active Material]
In this step, the first active material, the conductive auxiliary agent, the binder, and other components (for example, a supporting salt (lithium salt), an ion conductive polymer, a polymerization initiator, etc.) as necessary in a solvent. Mix. Separately, a second active material, a conductive additive, a binder, and other components (for example, a supporting salt (lithium salt), an ion conductive polymer, a polymerization initiator, etc.) are mixed in a solvent. To do. In this way, a slurry containing the first active material (hereinafter also simply referred to as “first active material slurry”) and a slurry containing the second active material (hereinafter also simply referred to as “second active material slurry”). Are prepared respectively. Since the specific form of each component blended in the active material slurry is as described in the column of the configuration of the electrode of the present invention, detailed description is omitted here.

  The type of the solvent is not particularly limited, and conventionally known knowledge about electrode production can be referred to as appropriate. As an example of the solvent, N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide and the like can be used. When employing vinylidene fluoride (PVdF) as the binder, NMP may be used as a solvent.

  The mixing means is not particularly limited, but if a method of dispersing the binder in a solution in which the binder is dissolved in advance is used, the active material distribution becomes uniform in the coating film obtained in the coating film forming process described later. It is preferable because it is easy.

[Coating film forming process]
Subsequently, a current collector is prepared, and the first active material slurry and the second active material slurry prepared above are applied to the surface of the current collector and dried. Thereby, the coating film which consists of said 1st active material slurry and said 2nd active material slurry is formed in the surface of an electrical power collector. This coating film becomes an active material layer through a pressing step described later.

  The specific form of the current collector to be prepared is as described in the column of the configuration of the electrode of the present invention, and thus detailed description thereof is omitted here.

  The application means for applying the active material slurry is not particularly limited, and generally used means such as a self-propelled coater, a doctor blade method, and a spray method may be employed.

  There is no particular limitation on the method of making the arrangement in the area direction of the first active material layer and the second active material layer into a desired form. For example, after applying the first active material slurry in a desired shape onto a current collector, a Teflon (registered trademark) sheet is covered on the portion where the first active material slurry is applied, and the second active material slurry is applied to the current active material slurry. The method of apply | coating is mentioned. In addition, for example, after the second active material slurry is applied in a desired shape on a current collector, a portion where the second active material slurry is applied is covered with a Teflon (registered trademark) sheet, and the first active material is covered. The method of apply | coating a slurry is mentioned.

  A coating film is formed according to the desired arrangement | positioning form of the electrical power collector and active material layer in the electrode manufactured. For example, when the manufactured electrode is a bipolar electrode, a coating film containing a positive electrode active material is formed on one surface of the current collector, and a coating film containing a negative electrode active material is formed on the other surface. On the other hand, when an electrode that is not a bipolar type is manufactured, a coating film containing one of a positive electrode active material and a negative electrode active material is formed on both surfaces of one current collector.

  Thereafter, the coating film formed on the surface of the current collector is dried. Thereby, the solvent in a coating film is removed.

  The drying means for drying the coating film is not particularly limited, and conventionally known knowledge about electrode production is appropriately referred to, and examples thereof include heat treatment. The drying conditions (drying time, drying temperature, etc.) can be appropriately set according to the amount of slurry applied and the volatilization rate of the solvent in the slurry.

  When a coating film contains a polymerization initiator, the ion conductive polymer in a coating film is bridge | crosslinked by a crosslinkable group by performing a superposition | polymerization process further.

  The polymerization treatment in the polymerization step is not particularly limited, and conventionally known knowledge may be referred to as appropriate. For example, when the coating film contains a thermal polymerization initiator (AIBN or the like), the coating film is subjected to heat treatment. Moreover, when a coating film contains a photoinitiator (BDK etc.), light, such as an ultraviolet light, is irradiated. In addition, the heat processing for thermal polymerization may be performed simultaneously with said drying process, and may be performed before or after the said drying process.

[Pressing process]
Then, the laminated body produced through the said coating-film formation process is pressed to the lamination direction. Thereby, the battery electrode of the present invention is completed. At this time, the porosity of the active material layer can be controlled by adjusting the pressing conditions.

  Specific means and pressing conditions for the press treatment are not particularly limited, and can be appropriately adjusted so that the porosity of the active material layer after the press treatment becomes a desired value. Specific examples of the press process include a hot press machine and a calendar roll press machine.

  The battery electrode of the present invention can be applied to any of a positive electrode, a negative electrode, and a bipolar electrode. A lithium ion secondary battery including the electrode of the present invention as at least one electrode belongs to the technical scope of the present invention. By adopting such a configuration, the output characteristics of the lithium ion secondary battery can be effectively improved.

  The battery in which the electrode of the present invention is used may be a bipolar lithium ion secondary battery (hereinafter also referred to as “bipolar battery”). FIG. 4 is a cross-sectional view showing a lithium ion secondary battery which is a bipolar battery. Hereinafter, the bipolar battery shown in FIG. 4 will be described in detail as an example, but the technical scope of the present invention is not limited to such a form.

  The bipolar battery 40 shown in FIG. 4 has a structure in which a substantially rectangular battery element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate sheet 429 that is an exterior.

  As shown in FIG. 4, the battery element 421 of the bipolar battery 40 includes a bipolar electrode (not shown) in which a positive electrode active material layer 43 and a negative electrode active material layer 45 are formed on each surface of a current collector 41. Have a plurality. Each bipolar electrode is stacked via an electrolyte layer 47 to form a battery element 421. At this time, each bipolar electrode and electrolyte layer are arranged such that the positive electrode active material layer 43 of one bipolar electrode and the negative electrode active material layer 45 of another bipolar electrode adjacent to the one bipolar electrode face each other through the electrolyte layer 47. 47 are stacked.

  The adjacent positive electrode active material layer 43, electrolyte layer 47, and negative electrode active material layer 45 constitute one unit cell layer 49. Therefore, it can be said that the bipolar battery 40 has a configuration in which the single battery layers 49 are stacked. Further, an insulating layer 431 for insulating between adjacent current collectors 41 is provided on the outer periphery of the unit cell layer 49. The current collector (outermost layer current collector) (41a, 41b) located in the outermost layer of the battery element 421 has a positive electrode active material layer 43 (positive electrode side outermost layer current collector 41a) or a negative electrode only on one side. One of the active material layers 45 (the negative electrode side outermost layer current collector 41b) is formed.

  Furthermore, in the bipolar battery 40 shown in FIG. 4, the positive electrode side outermost layer current collector 41a is extended to form a positive electrode tab 425, which is led out from a laminate sheet 429 which is an exterior. On the other hand, the negative electrode side outermost layer current collector 41b is extended to form a negative electrode tab 427, which is similarly derived from the laminate sheet 429.

  Hereinafter, members constituting the bipolar battery 40 of FIG. 4 will be briefly described. However, since the components constituting the electrode are as described above, the description thereof is omitted here. Further, the technical scope of the present invention is not limited to the following forms, and conventionally known forms can be similarly adopted.

[Electrolyte layer]
As the electrolyte constituting the electrolyte layer 47, a liquid electrolyte or a polymer electrolyte can be used.

  The liquid electrolyte has a form in which a lithium salt as a supporting salt is dissolved in an organic solvent as a plasticizer. Examples of the organic solvent that can be used as the plasticizer include carbonates such as ethylene carbonate (EC) and propylene carbonate (PC). Further, as the supporting salt (lithium salt), a compound that can be added to the active material layer of the electrode, such as LiBETI, can be similarly employed.

  On the other hand, the polymer electrolyte is classified into a gel electrolyte containing an electrolytic solution and an intrinsic polymer electrolyte containing no electrolytic solution.

  The gel electrolyte has a configuration in which the above liquid electrolyte is injected into a matrix polymer made of an ion conductive polymer. Examples of the ion conductive polymer used as the matrix polymer include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. In such polyalkylene oxide polymers, electrolyte salts such as lithium salts can be well dissolved.

  In the case where the electrolyte layer 17 is composed of a liquid electrolyte or a gel electrolyte, a separator may be used for the electrolyte layer 17. Specific examples of the separator include a microporous film made of polyolefin such as polyethylene or polypropylene.

  The intrinsic polymer electrolyte has a structure in which a supporting salt (lithium salt) is dissolved in the matrix polymer, and does not include an organic solvent that is a plasticizer. Therefore, when the electrolyte layer 17 is composed of an intrinsic polymer electrolyte, there is no fear of liquid leakage from the battery, and the reliability of the battery can be improved.

  The matrix polymer of the gel electrolyte or the intrinsic polymer electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, etc. are performed on a polymerizable polymer (for example, PEO or PPO) for forming a polymer electrolyte using an appropriate polymerization initiator. A polymerization treatment may be performed.

[Insulation layer]
In the bipolar battery 40, an insulating layer 431 is usually provided around each single battery layer 49. The insulating layer 431 is provided for the purpose of preventing the adjacent current collectors 41 in the battery from contacting each other and short-circuiting due to slight unevenness of the end of the single cell layer 49 in the battery element 421. It is done. By installing such an insulating layer 431, long-term reliability and safety are ensured, and a high-quality bipolar battery 40 can be provided.

  The insulating layer 431 may be any layer having insulating properties, sealing properties against falling off of the solid electrolyte, sealing properties against moisture permeation from the outside (sealing properties), heat resistance at the battery operating temperature, and the like. For example, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin, rubber and the like can be used. Of these, urethane resins and epoxy resins are preferred from the viewpoints of corrosion resistance, chemical resistance, ease of production (film forming properties), economy, and the like.

[tab]
In the bipolar battery 40, the tabs (the positive electrode tab 425 and the negative electrode tab 427) electrically connected to the outermost current collector (41a, 41b) are taken out of the exterior for the purpose of taking out the current outside the battery. . Specifically, a positive electrode tab 425 electrically connected to the positive electrode outermost layer current collector 41a and a negative electrode tab 427 electrically connected to the negative electrode outermost layer current collector 41b are provided outside the exterior. It is taken out.

  The material of the tabs (the positive electrode tab 425 and the negative electrode tab 427) is not particularly limited, and a known material conventionally used as a tab for a bipolar battery can be used. Examples thereof include aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof. Note that the same material may be used for the positive electrode tab 425 and the negative electrode tab 427, or different materials may be used. As shown in FIG. 2, the outermost layer current collector (41a, 41b) may be extended to form tabs (425, 427), or a separately prepared tab may be connected to the outermost layer current collector. .

[Exterior]
In the bipolar battery 40, the battery element 421 is preferably housed in an exterior such as a laminate sheet 429 in order to prevent external impact and environmental degradation during use. The exterior is not particularly limited, and a conventionally known exterior can be used. A polymer-metal composite laminate sheet or the like excellent in thermal conductivity can be preferably used in that heat can be efficiently transferred from a heat source of an automobile and the inside of the battery can be rapidly heated to the battery operating temperature.

(battery)
The present invention also forms a battery excellent in low temperature operability by connecting a plurality of first unit cell layers containing the first active material and a plurality of second unit cell layers containing the second active material. can do. In this case, the arrangement form is preferably an arrangement form in which the first unit cell layer is arranged inside the battery and the second unit cell layer is arranged outside the battery. By adopting such an arrangement, heat generated in the first single cell layer due to discharge can be efficiently released to the second single cell layer, and a battery excellent in low temperature operability can be obtained. . When the first active material is a positive electrode active material, it is preferable that the positive electrode active material layer of the first single battery layer includes only the first active material having a low electric resistance value. When the second active material is a positive electrode active material, it is preferable that the positive electrode active material layer of the second single battery layer includes only the second active material having a high electric resistance value. When the first active material is a negative electrode active material, it is preferable that the negative electrode active material layer of the first single battery layer includes only the first active material having a low electric resistance value. When the second active material is a negative electrode active material, it is preferable that the negative electrode active material layer of the second single battery layer includes only the second active material having a high electric resistance value.

  FIG. 5 shows a battery in which one first cell layer 51 containing only the first active material as an active material and one second cell layer 52 containing only the second active material as an active material are connected. 50 is a schematic plan view (A in FIG. 5) and a schematic cross-sectional view (B in FIG. 5). Further, FIG. 6 shows that two first cell layers 61 including only the first active material as an active material and two second cell layers 62 including only the second active material as an active material are connected. FIG. In the battery shown in FIG. 5, the first single battery layer 51 including only the first active material is disposed inside the battery, and the second single battery layer 52 including only the second active material is disposed outside. . In the battery shown in FIG. 6, the first single battery layer 61 including only the first active material is disposed on the innermost side of the battery, and the second single battery layer 62 including only the second active material is disposed on the outermost side. Has been placed. The first unit cell layers 61 and the second unit cell layers 62 are alternately and concentrically arranged from the inner side to the outer side in the stacking direction. With such a structure, a battery having excellent low temperature operability can be formed. In addition, the connection method of the single battery layer (51, 61) containing only the 1st active material as an active material which comprises a battery, and the single battery layer (52, 62) containing only a 2nd active material as an active material is as follows. There is no particular limitation. All of the plurality may be connected in parallel, all of the plurality may be connected in series, or series connection and parallel connection may be combined.

(Battery)
As shown in FIG. 7, the assembled battery 70 can be configured by connecting a plurality of bipolar batteries including the above-described battery electrode of the present invention. Each bipolar battery 40 is connected by connecting the positive electrode tab 425 and the negative electrode tab 427 of each bipolar battery 40 using a bus bar. On one side surface of the assembled battery 70, electrode terminals (72, 73) are provided as electrodes of the entire assembled battery 70.

  The connection method when connecting the plurality of bipolar batteries 40 constituting the assembled battery 70 is not particularly limited, and a conventionally known method can be appropriately employed. For example, a technique using welding such as ultrasonic welding or spot welding, or a technique of fixing using rivets, caulking, or the like can be employed. According to such a connection method, the long-term reliability of the assembled battery 70 can be improved.

  According to the assembled battery 70, since each bipolar battery 40 constituting the assembled battery 70 is excellent in low temperature operability, an assembled battery excellent in low temperature operability can be provided.

  The bipolar batteries 40 constituting the assembled battery 70 may be connected in parallel, or may be connected in series, or a combination of series connection and parallel connection. May be.

(vehicle)
The vehicle is configured by mounting the above-described bipolar battery 40, the above-described batteries (50, 60), or the above-described assembled battery 70 as a motor driving power source. Examples of the vehicle using the bipolar battery 40, the battery (50, 60), or the assembled battery 70 as a power source for the motor include a complete electric vehicle that does not use gasoline. In addition, hybrid vehicles such as series hybrid vehicles and parallel hybrid vehicles, and vehicles that drive wheels with a motor, such as fuel cell vehicles, can be cited.

  For reference, FIG. 8 shows a schematic diagram of an automobile 80 on which the assembled battery 70 is mounted. The assembled battery 70 mounted on the automobile 80 has the characteristics as described above.

  As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various modifications, omissions, and additions can be made by those skilled in the art. For example, in the present specification, a bipolar lithium ion secondary battery (bipolar battery) has been described as an example, but the technical scope of the battery of the present invention is not limited to a bipolar battery. For example, a lithium ion secondary battery that is not a bipolar type may be used. For reference, FIG. 9 is a cross-sectional view showing an outline of a lithium ion secondary battery 90 that is not a bipolar type.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

Example 1
<Preparation of active material slurry>
1. Preparation of positive electrode active material slurry A As a positive electrode active material, LiFePO ₄ (86% by mass, electrical resistance: 30 mΩcm ² ) having an average particle diameter of 1.9 μm, acetylene black (6% by mass) as a conductive auxiliary agent, and as a binder An appropriate amount of N-methyl-2-pyrrolidone (NMP), which is a slurry viscosity adjusting solvent, was added to a solid content of polyvinylidene fluoride (PVdF) (8% by mass) to prepare a positive electrode active material slurry A.

2. Preparation of Positive Electrode Active Material Slurry B As the positive electrode active material, LiMnPO ₄ (86% by mass, electric resistance: 50 mΩcm ² ) having an average particle diameter of 10 μm, acetylene black (6% by mass) as a conductive auxiliary agent, and a binder. A positive electrode active material slurry by adding N-methyl-2-pyrrolidone (NMP), which is a slurry viscosity adjusting solvent, to a solid content of polyvinylidene fluoride (PVdF) (8% by mass) so as to have a slurry viscosity. A was prepared.

3. Preparation of Negative Electrode Active Material Slurry For a solid content comprising mesocarbon microbeads (MCMB) (90% by mass) having an average particle diameter of 10 μm as a negative electrode active material and polyvinylidene fluoride (PVdF) (10% by mass) as a binder. Then, an appropriate amount of N-methyl-2-pyrrolidone (NMP), which is a slurry viscosity adjusting solvent, was added to prepare a negative electrode active material slurry.

<Preparation of test positive electrode>
Above 1. The positive electrode active material slurry A prepared in step 6 was formed into a rectangular shape (5 cm × 5 cm) by spray coating on one side of an Al foil (thickness 20 μm, size 6.8 cm × 6.8 cm) as a current collector. The coating amount was 4 mg / cm ² . Next, a Teflon (registered trademark) sheet is covered on the portion where the positive electrode active material slurry A is applied, and the above 2. The positive electrode active material slurry B prepared in (1) was applied at a coating amount of 10.2 mg / cm ² by spray coating. The application shape of the positive electrode active material slurry B was a concentric rectangular shape surrounding the application portion of the positive electrode active material slurry A as shown in FIG. Thereafter, the obtained laminate was dried using a press machine under the conditions of 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry A and B was 50 μm. The application area of the positive electrode active material slurry A was 25 cm ² , and the application area of the positive electrode active material slurry B was 21 cm ² .

<Preparation of test negative electrode>
The negative electrode slurry prepared above was applied onto a copper foil (thickness: 20 μm) as a negative electrode current collector with a doctor blade. The amount of solid content applied was 30 mg / cm ² . Thereafter, the obtained laminate was dried at 80 ° C., and then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied negative electrode slurry layer was 30 μm. An output terminal was connected to the current collector to obtain a test negative electrode.

<Preparation of electrolyte>
Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 1 to obtain a plasticizer (organic solvent) for the electrolytic solution. Then, the plasticizer, the addition of LiPF ₆ as lithium salt to a concentration of 1M, to prepare an electrolytic solution.

<Production of evaluation cell>
A polyethylene microporous membrane (size: 7.8 cm × 7.8 cm, thickness: 25 μm, porosity: 60%, permeability) using the test positive electrode and the test negative electrode produced above. (Temperature: 90 s / cc). Next, the obtained sandwiched body was set in a small cell. Thereafter, the electrolytic solution prepared above was injected into the cell and vacuum sealed so that the output terminal was exposed from the cell, thereby completing the evaluation cell.

(Example 2)
The positive electrode active material slurry A and the positive electrode active material slurry B were applied by a spray coating method in a coating shape as shown in FIG. Specifically, first, the above 1. The positive electrode active material slurry A prepared in step 6 was sprayed onto one side of an Al foil (thickness 20 μm, size 6.8 cm × 6.8 cm) as a current collector in a concentric rectangular shape shown in FIG. The coating amount was 4 mg / cm ² . Next, a Teflon (registered trademark) sheet is covered on the portion where the positive electrode active material slurry A is applied, and the above 2. The positive electrode active material slurry B prepared in (1) was applied at a coating amount of 10.2 mg / cm ² by spray coating. The application shape of the positive electrode active material slurry B was alternately and concentric with respect to the application portion of the positive electrode active material slurry A as shown in FIG. Thereafter, the obtained laminate was dried using a press machine under the conditions of 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry A and B was 50 μm. The application area of the positive electrode active material slurry A was 24 cm ² , and the application area of the positive electrode active material slurry B was 22 cm ² .

  An evaluation cell was produced in the same manner as in Example 1 except that the test positive electrode was produced in this manner.

(Example 3)
The positive electrode active material slurry A and the positive electrode active material slurry B were applied in a coating shape as shown in FIG. Specifically, first, the above 1. The positive electrode active material slurry A prepared in 1 above was sprayed onto one side of an Al foil (thickness 20 μm, size 6.8 cm × 6.8 cm) as a current collector in an island shape as shown in FIG. It apply | coated with the application quantity of 4 mg / cm < ² >. Next, a Teflon (registered trademark) sheet is covered on the portion where the positive electrode active material slurry A is applied, and the above 2. The positive electrode active material slurry B prepared in (1) was applied at a coating amount of 10.2 mg / cm ² by spray coating. The application shape of the positive electrode active material slurry B was set to the sea shape shown in FIG. Thereafter, the obtained laminate was dried using a press machine under the conditions of 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry A and B was 50 μm. The application area of the positive electrode active material slurry A was 22 cm ² , and the application area of the positive electrode active material slurry B was 24 cm ² .

  An evaluation cell was produced in the same manner as in Example 1 except that the test positive electrode was produced in this manner.

Example 4
[Production of first evaluation cell]
<Preparation of test positive electrode>
Above 1. The positive electrode active material slurry A prepared in (1) was applied to the entire surface of one side of an Al foil (thickness: 20 μm), which is a current collector, at a coating amount of 6.4 mg / cm ² by spray coating. The dried laminate was then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry layer was 50 μm.

<Preparation of test negative electrode>
The negative electrode slurry prepared above was applied onto a copper foil (thickness: 20 μm) as a negative electrode current collector with a doctor blade. The amount of solid content applied was 30 mg / cm ² . Thereafter, the obtained laminate was dried at 80 ° C., and then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied negative electrode slurry layer was 30 μm. An output terminal was connected to the current collector to obtain a test negative electrode.

<Preparation of electrolyte>
Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 1 to obtain a plasticizer (organic solvent) for the electrolytic solution. Then, the plasticizer, the addition of LiPF ₆ as lithium salt to a concentration of 1M, to prepare an electrolytic solution.

<Production of first evaluation cell>
A polyethylene microporous membrane (size: 7.8 cm × 7.8 cm, thickness: 25 μm, porosity: 60%, permeability) using the test positive electrode and the test negative electrode produced above. (Temperature: 90 s / cc). Next, the obtained sandwiched body was set in a small cell. Thereafter, the electrolytic solution prepared above was injected into the cell and vacuum sealed so that the output terminal was exposed from the cell to complete the first evaluation cell.

[Production of Second Evaluation Cell]
<Preparation of test positive electrode>
2. The positive electrode active material slurry B prepared in (1) was applied to the entire surface of one side of an Al foil (thickness: 20 μm), which is a current collector, at a coating amount of 6.4 mg / cm ² by spray coating. The dried laminate was then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry layer was 50 μm.

<Preparation of test negative electrode>
The negative electrode slurry prepared above was applied onto a copper foil (thickness: 20 μm) as a negative electrode current collector with a doctor blade. The amount of solid content applied was 30 mg / cm ² . Thereafter, the obtained laminate was dried at 80 ° C., and then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied negative electrode slurry layer was 30 μm. An output terminal was connected to the current collector to obtain a test negative electrode.

<Preparation of electrolyte>
Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 1 to obtain a plasticizer (organic solvent) for the electrolytic solution. Then, the plasticizer, the addition of LiPF ₆ as lithium salt to a concentration of 1M, to prepare an electrolytic solution.

<Production of Second Evaluation Cell>
A polyethylene microporous membrane (size: 7.8 cm × 7.8 cm, thickness: 25 μm, porosity: 60%, permeability) using the test positive electrode and the test negative electrode produced above. (Temperature: 90 s / cc). Next, the obtained sandwiched body was set in a small cell. Thereafter, the electrolytic solution prepared above was poured into the cell and vacuum sealed so that the output terminal was exposed from the cell, thereby completing the second evaluation cell.

[Production of battery]
A battery having the shape shown in FIG. 5 was produced. Specifically, the first evaluation cell produced above was rolled up and inserted into a cylindrical cell (corresponding to the portion denoted by reference numeral 51 in FIG. 5). A cylindrical cell (corresponding to a portion denoted by reference numeral 52 in FIG. 5) was produced so as to cover the outside of the cylindrical cell, and the second evaluation cell was rolled up and inserted.

(Example 5)
A battery having the shape shown in FIG. 6 was produced using two each of the first evaluation cell and the second evaluation cell produced in Example 4. Cylindrical cells were produced in the same manner as in Example 4, and first evaluation cells and second evaluation cells were alternately arranged.

(Comparative Example 1)
2. The positive electrode active material slurry B prepared in step 1 was applied to one side of an Al foil (thickness 20 μm) as a current collector in a rectangular shape (5 cm × 5 cm) at a coating amount of 6.4 mg / cm ² by spray coating. (Reference numeral 102 in FIG. 10). Next, a Teflon (registered trademark) sheet is covered on the portion where the positive electrode active material slurry B is applied, and the above 1. The positive electrode active material slurry A prepared in (1) was applied at a coating amount of 10.2 mg / cm ² by a spray coating method (reference numeral 101 in FIG. 10). The application shape of the positive electrode active material slurry A was a concentric rectangular shape surrounding the application portion of the positive electrode active material slurry B as shown in FIG. The dried laminate was then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry layer was 50 μm. The application area of the positive electrode active material slurry A was 21 cm ² , and the application area of the positive electrode active material slurry B was 25 cm ² .

  Thus, an evaluation cell was produced in the same manner as in Example 1 except that the test positive electrode was produced.

(Comparative Example 2)
2. As shown in FIG. 11, the positive electrode active material slurry B prepared in (1) was applied to the entire surface of one surface of an Al foil (thickness: 20 μm) as a current collector at a coating amount of 6.4 mg / cm ² by spray coating. The dried laminate was then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry B layer was 50 μm.

  Thus, an evaluation cell was produced in the same manner as in Example 1 except that the test positive electrode was produced.

(Comparative Example 3)
Above 1. As shown in FIG. 12, the positive electrode active material slurry A prepared in (1) was applied to the entire surface of one side of an Al foil (thickness 20 μm) as a current collector by a spray coating method at a coating amount of 6.4 mg / cm ² . The dried laminate was then pressed using a press machine at 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry A layer was 50 μm.

  Thus, an evaluation cell was produced in the same manner as in Example 1 except that the test positive electrode was produced.

(Comparative Example 4)
The positive electrode active material slurry A and the positive electrode active material slurry B were applied in a coating shape as shown in FIG. Specifically, first, the above 2. The positive electrode active material slurry B prepared in 1 above was sprayed onto one side of an Al foil (thickness 20 μm, size 6.8 cm × 6.8 cm) as a current collector into the island shape shown in FIG. It apply | coated with the application quantity of 4 mg / cm < ² > (code | symbol 132 of FIG. 13). Next, a Teflon (registered trademark) sheet is covered on the portion where the positive electrode active material slurry B is applied, and the above 2. The positive electrode active material slurry A prepared in (1) was applied at a coating amount of 10.2 mg / cm ² by spray coating. The application shape of the positive electrode active material slurry A was set to be a sea shape as shown in FIG. 9 (reference numeral 131 in FIG. 13). Thereafter, the obtained laminate was dried using a press machine under the conditions of 25 ° C. and 1 MPa so that the thickness of the applied positive electrode active material slurry A and B was 50 μm. The application area of the positive electrode active material slurry A was 22 cm ² , and the application area of the positive electrode active material slurry B was 24 cm ² .

  Thus, an evaluation cell was produced in the same manner as in Example 1 except that the test positive electrode was produced.

(Evaluation)
Using the evaluation cells manufactured in Examples 1 to 5 and Comparative Examples 1 to 4, the resistance increase rate, the low temperature output, and the normal temperature output were measured.

  The resistance increase rate, the low temperature output, and the normal temperature output were measured using a device (product number: HJ-1001 SM8) manufactured by Hokuto Denko Corporation.

  The room temperature output was calculated from the voltage after 10 seconds when 3C discharge was performed in a constant temperature bath at 25 ° C. and the voltage before discharge. The low temperature output was similarly calculated in a -20 ° C constant temperature bath.

  The rate of increase in resistance was calculated from the voltage after 100 cycles after the cycle test was conducted from SOC 0% to 100%.

  The measurement results are shown in Table 1 below.

  As is clear from Table 1, the secondary batteries (Examples 1 to 3) using the battery electrode of the present invention and the batteries of the present invention (Examples 4 to 5) have excellent low-temperature operability. all right.

It is the plane schematic diagram and cross-sectional schematic diagram which represented typically the form which has arrange | positioned two types of active material layers on the electrical power collector in the shape of a concentric rectangle. It is the plane schematic diagram and cross-sectional schematic diagram which represented typically the form which has arrange | positioned two types of active material layers alternately and concentric rectangular shape on the electrical power collector. It is the plane schematic diagram and the cross-sectional schematic diagram which represented typically the form which has arrange | positioned the 1st active material layer to the island shape on the electrical power collector. It is sectional drawing which shows the outline | summary of a bipolar lithium ion secondary battery. It is the plane schematic diagram and cross-sectional schematic diagram of the battery which respectively connected the 1st single cell layer and the 2nd single cell layer. FIG. 3 is a schematic plan view of a battery in which two first cell layers and two second cell layers are connected. It is a perspective view which shows one Embodiment of the assembled battery using the electrode for batteries of this invention. It is the schematic which shows one Embodiment of the motor vehicle carrying the assembled battery using the battery electrode of this invention. It is sectional drawing which shows the outline | summary of the lithium ion secondary battery which is not a bipolar type. 6 is a schematic plan view showing a positive electrode produced in Comparative Example 1. FIG. 6 is a schematic plan view showing a positive electrode produced in Comparative Example 2. FIG. 10 is a schematic plan view showing a positive electrode produced in Comparative Example 3. FIG. 6 is a schematic plan view showing a positive electrode produced in Comparative Example 4. FIG.

Explanation of symbols

10, 20, 30 Battery electrode,
11, 21, 31, 41 Current collector,
12, 22, 32 First active material layer,
13, 23, 33 Second active material layer,
40 bipolar lithium-ion secondary battery 43 positive electrode active material layer,
45 negative electrode active material layer,
47 electrolyte layer,
49 cell layer,
50, 60 batteries,
51, 61 first cell layer,
52, 62 second cell layer,
70 battery packs,
72, 73 electrode terminals,
80 cars,
90 A lithium ion secondary battery which is not a bipolar type.
101, 121, 131 layers formed from the positive electrode active material slurry A,
102, 112, 132 layers formed from the positive electrode active material slurry B,
421 battery element,
425 positive terminal,
427 negative terminal,
429 laminate sheet,
431 insulating layer,
433 positive electrode current collector,
435 Negative electrode current collector.

Claims (12)

At least one first active material layer comprising a first active material;
And comprising at least one second active material layer including a second active material having a higher electrical resistance value than the first active material,
The battery active electrode, wherein the second active material layer is disposed outside in an area direction from at least one layer of the first active material layer.   The battery electrode according to claim 1, wherein the first active material layers and the second active material layers are alternately and concentrically arranged from the inner side to the outer side in the area direction.   The battery electrode according to claim 1, wherein the first active material layer is disposed in an island shape, and the second active material layer is disposed in a sea shape surrounding the first active material layer. The battery electrode according to claim 1, wherein the first active material is LiFePO ₄ . A lithium ion secondary battery including at least one single cell layer in which a positive electrode, an electrolyte layer, and a negative electrode are laminated in this order,
The lithium ion secondary battery whose at least one of the said positive electrode or the said negative electrode is the electrode for batteries of any one of Claims 1-4.   The lithium ion secondary battery according to claim 5, wherein the electrolyte layer includes a liquid electrolyte, a gel electrolyte, or an intrinsic polymer electrolyte.   The lithium ion secondary battery according to claim 5 or 6, which is a bipolar lithium ion secondary battery.   The assembled battery using the lithium ion secondary battery of any one of Claims 5-7. A first cell layer containing a first active material;
A second unit cell layer including a second active material having a higher electrical resistance value than the first active material,
The battery, wherein the second unit cell layer is disposed outside in the stacking direction from at least one layer of the first unit cell layer.   10. The battery according to claim 9, wherein the first single battery layer and the second single battery layer are alternately and concentrically arranged from the inner side to the outer side in the stacking direction. The battery according to claim 9 or 10, wherein the first active material is LiFePO ₄ .   The lithium ion secondary battery according to any one of claims 5 to 7, the assembled battery according to claim 8, or the battery according to any one of claims 9 to 11 is mounted as a motor driving power source. Vehicle.

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