KR20130124257A - Electrode assembly, manufacturing the same, and method of charging and discharging a battery - Google Patents

Abstract

The present invention relates to an electrode assembly, a manufacturing method thereof, and a charging and discharging method of a battery. The electrode assembly according to an embodiment of the present invention comprises: a current collector; a first electricity active material layer arranged on the current collector; and a first porous conductivity network layer arranged on the other periphery of the first electricity active material layer being in contact with the current collector, and partially or entirely caved into the first electricity active material layer.

Description

Electrode assembly, manufacturing method thereof, and charging and discharging method of battery TECHNICAL FIELD

TECHNICAL FIELD The present invention relates to battery technology, and more particularly, to an electrode assembly, a manufacturing method thereof, and a charging and discharging method of a battery.

BACKGROUND ART [0002] Recently, with the development of semiconductor manufacturing technology and communication technology, an industry related to portable electronic devices has grown, and demand for development of alternative energy due to environmental preservation and depletion of resources has been sharpened, battery related technology is being actively studied. The battery is divided into a primary battery that can be used once for a certain life and a secondary battery that can be repeatedly used through recharging. As a raw material of the battery, lithium is the lightest of the metals known in nature, the lowest standard reduction potential, has the advantage of high energy density at the time of battery manufacturing, as well as high voltage. Accordingly, research on primary batteries and secondary batteries using lithium has attracted much attention.

Primary batteries are primarily used for mains or backup power in portable electronic devices. Secondary batteries range from batteries for small devices such as mobile phones, notebook PCs, mobile displays, to medium to large batteries for electric vehicles and hybrid vehicles. The field of application is gradually expanding.

These batteries are basically required to have a high energy density, low charge and discharge speed, charge and discharge efficiency and cycle characteristics, as well as high stability and economy, while being small in weight and volume.

Related Prior Art Literature

[Patent Document 1] Korean Publication 10-2008-0038806

[Patent Document 2] Korean Unexamined Patent Publication 10-2010-0093375

[Patent Document 3] Korean Unexamined Patent Publication 10-2009-0001316

[Special Document 4] Japanese Patent Application Laid-Open No. 11-213991

The technical problem to be solved by the present invention is to provide an electrode assembly that can be applied to a battery having not only high energy density but also excellent charge / discharge efficiency, charge / discharge rate, and cycle characteristics.

In addition, another technical problem to be solved by the present invention is to provide a manufacturing method that can easily manufacture the electrode assembly having the above-described advantages.

In addition, another technical problem to be solved by the present invention is to provide a charging or discharging method using the electrode assembly having the above-described advantages.

An electrode assembly according to an embodiment of the present invention for achieving the above technical problem, the current collector; A first electrical active material layer laminated on the current collector; And a first porous conductive network layer laminated on a main surface opposite to a main surface of the first electrical active material layer in contact with the current collector and at least partially embedded in the first electrical active material layer.

In some embodiments, the current collector may comprise a metal foil, a metal mesh, or a combination thereof. In addition, the first porous conductive network layer may include a metal foam, carbon fiber, metal long fiber layer, and combinations thereof. In addition, the metal long fiber layer may have a nonwoven structure.

The electrode assembly may further include a base porous conductive network layer stacked between the current collector and the first electrically active material layer and at least partially embedded in the first electrically active material layer. In addition, the battery may further include a second electrical active material layer laminated on the main surface opposite the main surface of the first porous conductive network layer in contact with the first electrical active material layer. In this case, the battery may further include a second porous conductive network layer laminated on the main surface opposite to the main surface of the second electrical active material layer in contact with the first porous conductive network layer.

In some embodiments, the second porous conductive network layer may comprise a metal foam, carbon fiber, metal long fiber layer, and combinations thereof. In addition, the metal long fiber layer may have a nonwoven structure.

In some embodiments, the thickness of the first porous conductive network layer may be in the range of 0.5 μm to 100 μm. In addition, the metal long fiber layer comprises a plurality of segmented metal long fibers, the plurality of metal long fibers may have a length in the range of 10 ㎛ to 100 mm.

According to another aspect of the present invention, there is provided a method of manufacturing an electrode assembly, including: providing a current collector; Providing a first slurry layer comprising an electrical active material on the current collector; Providing a first porous conductive network layer on the first slurry layer; Drying the first slurry layer provided with the first porous conductive network layer; And forcing at least a portion of the first porous conductive network layer to be embedded into the first slurry layer.

In some embodiments, prior to providing the first slurry layer, providing a ground porous conductive network layer on the current collector may be further performed. Further, before the drying of the first slurry layer, applying a second slurry layer including an electrical active material on the first porous conductive network layer; And drying the second slurry layer at the same time as the drying of the first slurry layer is further performed, and in the pressing, at least another part of the first metal long fiber layer may be embedded into the second slurry layer. Can be.

In another embodiment, prior to the drying of the second slurry layer simultaneously with the drying of the first slurry layer, providing a second porous conductive network layer on the second slurry layer may be further performed. In this case, in the pressing, at least a part of the second porous conductive network layer may be embedded into the second slurry layer.

After pressurizing at least a portion of the first porous conductive network layer to be embedded into the first slurry layer, providing a second slurry layer on the first porous conductive network layer may be further performed. In addition, providing a second porous conductive network layer on the second slurry layer; And drying the second slurry layer; Pressing the at least a portion of the second porous conductive network layer into the second slurry layer may be further performed.

In some embodiments, the providing of the first porous conductive network layer may be performed while an electric or magnetic field is applied to the first porous conductive network layer. In this case, an electromagnet or a permanent magnet may be used to apply the magnetic field. Alternatively, the fibrous body constituting the porous conductive network can be charged, in which case an electric field is applied.

According to another aspect of the present invention, there is provided a method of charging or discharging a battery, the method comprising: charging a partial capacity of a nominal capacity of the battery with a first charging C-rate; Charging the remaining capacity of the battery with a second charge C-rate lower than the first charge C rate; Or discharging a partial capacity of a nominal capacity of the battery with a first discharge C-rate; And charging the remaining capacity of the battery with a second discharge C-rate lower than the first discharge C rate.

The charging or discharging method may be performed by being coupled to a smart grid. The battery may be a battery including the electrode assembly of claim 1.

According to an embodiment of the present invention, the electrically active material layer is disposed between the current collector and the porous conductive network layer, so that the charging and discharging rate and the efficiency of the electrical active material layer are increased, and the porous conductive network layer is deformed. Since it is easy, it is possible to reduce the stress in the battery due to the volume change of the electrical active material layer during battery operation, thereby providing an electrode assembly that can be reduced or eliminated irreversible due to the charge and discharge cycle.

In addition, according to another embodiment of the present invention, since the electrode assembly having the above-described advantages can be manufactured only by a simple lamination process and a pressing process such as lamination or coating, a method of manufacturing an electrode assembly capable of improving productivity and simplifying equipment is provided. Can be provided.

Further, according to another embodiment of the present invention, the remaining capacity is charged by dividing the plurality of circuits while reducing the charge C-rate, or by discharging the remaining capacity by dividing the plurality of circuits by reducing the discharge C-rate. While charging or discharging to have a value, there is an advantage of shortening the time required for charging and discharging. Such a charging method may be accomplished in software, hardware, or a combination thereof, and may be implemented through the aforementioned battery managing system.

1 is a cross-sectional view showing an electrode assembly according to an embodiment of the present invention.
FIG. 2A is a graph illustrating charging characteristics of an electrode assembly according to a comparative example including only a current collector and an electrically active material layer without an electrode assembly and a porous conductive network layer according to an embodiment of the present invention shown in FIG. 1, and FIG. A graph showing discharge characteristics of an electrode assembly according to an embodiment of the present invention and an electrode assembly according to the comparative example. 3A to 3D are cross-sectional views illustrating a method of manufacturing an electrode assembly according to example embodiments.
4A is a cross-sectional view illustrating an electrode assembly according to another exemplary embodiment of the present invention, and FIG. 4B is a cross-sectional view illustrating a manufacturing method according to an exemplary embodiment of the electrode assembly of FIG. 4A.
5 is a cross-sectional view showing an electrode assembly according to another embodiment of the present invention.
6 is an exploded view showing a battery using the electrode structure according to an embodiment of the present invention.
7 is a graph showing a charging method according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In addition, in the following drawings, the thickness or size of each layer is exaggerated for convenience and clarity of description, the same reference numerals in the drawings refer to the same elements. As used herein, the term "and / or" includes any and all combinations of any of the listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers and / or portions, these members, components, regions, layers and / It is obvious that no. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, the first member, part, region, layer or portion, which will be discussed below, may refer to the second member, component, region, layer or portion without departing from the teachings of the present invention.

As used herein, the porous conductive network layer refers to a structure having a conductive network consisting of one-dimensional conductive paths and pores defined by a space between the conductive paths. The porous conductive network layer has plasticity and electrical conductivity, and the present invention relates to features and advantages thereof.

In addition, the long metal fibers used herein are manufactured by fiberizing metals such as stainless steel, aluminum, nickel, titanium and copper or alloys thereof, for example, having a diameter of several micrometers to several tens of micrometers. Refers to a metal yarn having a length of at least μm. The long metal fibers have the heat resistance, plasticity, and electrical conductivity of the metal, and at the same time have the advantage that the fiber-specific weaving and nonwoven processing process is possible. The present invention relates to features and advantages of applying such metal long fibers to the electrode structure of a cell.

The metal long fibers are prepared by holding the metal or alloy in a molten state in a suitable vessel and quenching and solidifying the molten metal by blowing it into the atmosphere through the injection hole of the vessel using a pressurization device such as a compressed gas or a piston. Can be. Alternatively, the long metal fibers can be produced by a known focus drawing method. By controlling the number, size and / or emergence of the injected molten metal, it is possible to control the thickness, uniformity, tissue such as nonwoven fabric, and the aspect ratio thereof. The metal long fibers constituting the battery of the present invention may include metal long fibers by other known manufacturing methods as well as the above-described manufacturing method, and the present invention is not limited thereto.

The term 'separation membrane' as used herein includes a separator generally used in a liquid electrolyte battery using a liquid electrolyte having a small affinity with the separator. In addition, the 'membrane' as used herein includes an intrinsic solid polymer electrolyte and / or a gel solid polymer electrolyte in which the electrolyte is strongly bound to the separator, so that the electrolyte and the separator are recognized as the same. Therefore, the separator should be defined in the meaning as defined herein.

1 is a cross-sectional view illustrating an electrode assembly 100 according to an embodiment of the present invention.

Referring to FIG. 1, the electrode assembly 100 may be disposed on a current collector 10, an electrical active material layer 20 on the current collector 10, and an opposite main surface of the main surface of the electrical active material layer 20 in contact with the current collector 10. It may include a three-dimensional porous conductive network layer 30 stacked on. The current collector 10 may be a metal foil or a metal mesh having a two-dimensional structure, and preferably, may be a metal foil having a continuous opposing area with respect to the three-dimensional porous conductive network layer 30. The current collector 10 may include aluminum or copper, depending on the polarity of the electrode assembly 100, which may include other known metals or alloys thereof, which are exemplary only.

The electrical active material layer 20 on the current collector 10 may include electrical active material particles and a binder. The electrically active material may be particles having an average size of 0.1 μm to 100 μm. If necessary, the particle size distribution of the electrically active material may be controlled through a classification process.

The electrical active material may be appropriately selected depending on the polarity of the electrode structure 100 and whether it is a primary battery or a secondary battery. For example, the cathode active material is a two-component or more oxide including lithium, nickel, cobalt, chromium, magnesium, strontium, vanadium, lanthanum, cerium, iron, cadmium, lead, titanium, molybdenum, or manganese. ), Phosphate, sulfide, fluoride or combinations thereof. However, this is exemplary and the cathode active material may be formed of other chalcogen compounds. Preferably, the cathode-type electrical active material comprises at least two or more of cobalt, copper, nickel, manganese, titanium and molybdenum suitable for lithium secondary batteries, O, F, S, P, and combinations thereof At least one non-metallic element selected from the group consisting of, for example, may be a compound of three or more components, such as Li [Ni, Mn, Co] O ₂ .

The anode active material may be, for example, a carbon-based material such as low crystalline carbon or high crystalline carbon. The low crystalline carbon may be, for example, soft carbon or hard carbon. The high crystalline carbon may include, for example, natural graphite, Kish graphite, pyrolytic carbon, liquid crystal pitch based carbon fiber, and carbon microspheres. carbon microbeads, mesophase pitches, hot calcined carbon such as petroleum or coal tar pitch derived cokes. This is exemplary and other carbon-based materials of diamonds and carbines may be applied.

In another embodiment, lithium powder may be used instead of the carbon-based material illustrated above. Alternatively, in addition to the carbon-based material, as the non-carbon-based active material, at least one of sodium, or other oxides, carbides, nitrides, sulfides, phosphides, selenides, and teleniumides suitable for NaS batteries may be included. Or monomagnetic fields such as silicon, germanium, tin, lead, antimony, bismuth, zinc, aluminum, iron and cadmium, intermetallic compounds having high lithium ion occlusion and release capability for high capacity of the cathode Or non-carbon based active materials such as oxide based materials may be used.

In another embodiment, a metal-based material having a high volumetric high volume change such as high efficiency Li intercalation material such as silicon (Si), bismuth (Bi), tin (Sn), aluminum (Al) or alloys thereof, or Electrically active materials containing these intermetallic compounds may be used.

In some embodiments, a binder may be added in the electrically active material layer 20 for confinement between the electrically active material in particle form. The binder is, for example, vinylidene fluoride-hexafluoropropylene copolymer (PVdF-co-HFP), polyvinylidene fluoride (PVdF), polyacrylonitrile, polymethylmethacryl Polymethylmethacrylate, polytetrafluoroethylene (PTFE), styrenebutadiene rubber (SBR), polyimide, polyurethane polymer, polyester polymer, and ethylene propylene diene copolymer (ethylene-propylene -diene copolymer (EPDM) may be a polymeric material. If necessary, the binder may include other polymer-based materials having conductivity, petroleum pitch, coal tar. The present invention is not limited by these examples, and the binder may be a material having stability while having a predetermined bonding force in an electrochemical environment without being dissolved in an electrolyte.

The binder may be added in a weight ratio of about 0.5 to 5% based on the total mixed weight of the electrical active material and the binder. Since the binder generally uses an organic solvent or water as a dispersion medium in terms of manufacturing process, it takes time for its drying and may remain in the electrical active material even after drying, thereby degrading the cycle characteristics of the battery. In addition, since the binder is an insulator, its use is preferably limited. In the electrode structure 100 according to the present embodiment, since the electrically active material in the form of particles is strongly bound between the current collector 10 and the 3D porous conductive network layer 30, the use of the binder may be minimized. .

In some embodiments, in particular in the case of the cathode active material, a conductive material may be further externalized together with the above-described electrically active material and the binder in the electrically active material layer 20. The conductive material may be uniformly mixed with the electrical active material and provided on the current collector 10. The conductive material may be added in a weight ratio of about 1% to 15% based on the total amount of the electrically active material, the binder, and the conductive material. The conductive material may be, for example, a fine carbon such as carbon black, acetylene black, ketjen black and ultra fine graphite particles, a nano metal particle paste, or a ratio such as an indium tin oxide paste or a carbon nanotube. It may be a nanostructure having a large surface area and low resistance.

The porous conductive network layer 30 is a conductive network layer made of a metal foam, a metal long fiber layer, carbon fiber or a combination thereof, preferably a conductive fiber layer such as a metal long fiber layer or carbon fiber, more preferably, a metal sheet Fibrous layer. Some or all of the porous conductive network layer 30 disposed on the electrically active material layer 20 may be embedded into the electrically active material layer 20 through a pressing process described later. When a part of the porous conductive network layer 30 is embedded into the electrically active material layer 20, a high density porous conductive network layer 30A exists on the surface of the electrically active material layer 20, and the porous conductive network layer 30 is present. The impregnated portion of can be mixed with the electrical active material, binder and other external additives in the electrical active material layer 20 to provide a low density porous conductive network layer 30B. As such, at least a part of the porous conductive network layer 30 may be embedded in the electrically active material layer 20 to secure a mechanical coupling between the porous conductive network layer 30 and the electrically active material layer 20.

When the porous conductive network layer 30 is made of a metal long fiber layer, the metal long fiber layer may have a nonwoven structure formed of a plurality of metal long fibers. The metal long fibers may comprise any one or combination of stainless steel, aluminum, nickel, titanium and copper or alloys thereof. The nonwoven fabric structure may use the fibrous properties of the plurality of metal long fibers to form a three-dimensional porous fiber structure in which the long metal fibers are bent and entangled with each other or formed by an entanglement process. In this respect, the metal foams chemically or integrally formed so that the one-dimensional linear structures that provide the conductive paths do not separate from one another are distinguished from metal long fiber layers that are entangled or entangled with one another.

The metallic long fibers may be segmented, and the average length of the segmented metallic long fibers may have a size in the range of 10 μm to 100 mm. In addition, the metal long fibers may have a thickness in the range of 1 μm to 50 μm. When the thickness of the metal long fibers is 1 μm or less, it is difficult to form using metal long fibers and artificially arrange the long metal fibers, thereby making it difficult to secure workability. In addition, when the thickness of the long metal fibers is 10 μm or more, it may be difficult to be incorporated into the electrically active material layer. As a result, the voltage division effect described later can be reduced. In addition, the strength of the long metal fibers may be increased, so that the processability of the electrode assembly may be reduced in the packaging step of the battery. Preferably, the metal long fibers may have a thickness of 1 μm to 10 μm.

The thickness of the electrically active material layer 20 may depend on the particle size of the electrically active material, and may have a thickness of 20 μm to 400 μm to have a suitable capacity. In addition, the thickness of the porous conductive network layer 30 is 0.5 μm to 100 μm, and preferably 10 μm to 40 μm. Since the thickness of the porous conductive network layer 30 is a factor that can increase the volume of the battery, it may be limited in the above-described range in terms of energy density.

FIG. 2A illustrates a comparative example including only the current collector 10 and the electrically active material layer 20 without the electrode assembly 100 of FIG. 1 and the porous conductive network layer 30 according to the embodiment of FIG. 1. 2B is a graph showing the discharge characteristics of the electrode assembly (100 of FIG. 1) and the electrode assembly according to the comparative example according to an embodiment of the present invention. In these graphs, curve R1 indicates the measured value for electrode assembly 100 of FIG. 1, and curve R2 indicates the measured value for electrode assembly according to a comparative example.

In the electrode assemblies for evaluation, lithium iron phosphate was used as the positive electrode active material, and the lithium iron phosphate was dispersed in an N-Methyl Pylolidone (NMP) solvent to prepare a slurry. Thereafter, the slurry was coated on aluminum foil to prepare a cathode assembly. The thickness of the applied active material layer was the same in both samples at about 40 μm, and the porous conductive network layer using the metal long fiber layer of the embodiment of the present invention was formed at a thickness of about 10 μm. The battery of the prepared sample is a half cell in which lithium metal is used as a negative electrode.

Referring to FIG. 2A, the battery using the electrode assembly according to the embodiment (curve R1) gradually decreases in capacity as the charging speed is increased, and maintains 40% or more of the nominal capacity even at 40 C-rate. However, in the battery using the electrode assembly according to the comparative example (curve R2), the capacity decreases rapidly as the charging speed increases, and at 40 C-rate, almost no charging occurs.

Referring to FIG. 2B, similarly to FIG. 2A, the battery using the electrode assembly according to the embodiment (curve R1) exhibits a characteristic that the capacity gradually decreases as the discharge rate increases. However, in the battery using the electrode assembly according to the comparative example (curve R2), the capacity decreases rapidly as the discharge rate increases, and almost no discharge occurs at 50 C-rate or more.

In general, batteries used in power tools usually require an output characteristic of about 10 C-rate, and in the case of a hybrid electric vehicle (HEV), an output characteristic of about 40 C-rate is required depending on performance. According to the embodiment of the present invention, in response to this demand, it can be seen that high output characteristics can be obtained in an electronic device or a power unit that requires high power. In addition, referring to the case of 40 C-rate of Figure 2a, it can be seen that according to an embodiment of the present invention, a high capacity battery can be charged more than 40% in a few minutes. In general, when the thickness of the active material is reduced, the resistance of the electrode or the resistance of lithium ions may be less, and thus the rate-rate characteristic may be improved. In this case, however, the amount of the active material is reduced, so that the capacity of the battery is also reduced. However, according to the embodiment of the present invention, there is an advantage that can improve the rate characteristic without reducing the thickness of the active material. This advantage is presumably because the porous conductive network layer functions as an intermediate electrode with the current collector 10 and the electrically active material layer interposed therebetween, providing a voltage division effect in the electrode structure. This may also be due to the effective reduction of the resistance inside the electrode assembly by the porous conductive network layer.

When the porous conductive network layer 30 is a metal long fiber layer having a nonwoven structure, some of the wires constituting the metal long fiber layer may penetrate into the electrically active material layer 20, and thus, the electrode assembly 100 In addition to reducing the internal resistance of), a locally strong electric field may be formed in the electrically active material layer 20. This strong electric field contributes to improving the charge and discharge speed and efficiency of the electrode assembly.

3A to 3D are cross-sectional views illustrating a method of manufacturing an electrode assembly according to example embodiments.

Referring to FIG. 3A, a current collector 10 is prepared. The current collector 10 may be, for example, the metal foil or the metal mesh described above. Referring to FIG. 3B, a slurry layer 20L containing an electrical active material, a binder, optionally a conductive material, and a suitable solvent is applied onto the current collector 10.

Referring to FIG. 3C, a porous conductive network layer 30L is formed on the slurry layer 20L. The porous conductive network layer 30L may include a structure in which they are combined, such as a metal foam, a carbon fiber, a metal long fiber layer, or a mixture of carbon fiber and metal long fiber. The metal long fiber layer may have a nonwoven structure composed of a plurality of metal long fibers. In some embodiments, the metal foam or metal long fiber layer is provided in the form of being wound on a rotary roll, so as to unwind the rotary roll before drying the slurry layer 20L, the metal foam or metal long fiber layer may be formed of an electrical active material layer ( Lamination on 20L).

In another embodiment, the plurality of metallic long fibers may be randomly spread on the slurry layer 20L to provide the porous conductive network layer 30L. For example, it is possible to randomly apply metal long fibers or carbon fibers onto the slurry layer 20L by wet or dry spraying apparatus such as an air spray or a corona gun. In this case, the fibers are embedded in the slurry layer 20L by applying a magnetic field to the slurry layer 20L using an electromagnet or a permanent magnet, or applying an electric field to the slurry layer 20L after charging the fibers. It can help you settle down.

Thereafter, the resultant product including the porous conductive network layer 30L is dried. The drying process may be performed by hot air, natural drying, vacuum drying, or the like.

Referring to FIG. 3D, after the slurry layer 20L is dried, the resultant is pressurized using a pressurizer such as a roll press, so that at least a portion of the porous conductive network layer 30 is embedded into the electrically active material layer 20. You can. When only a portion of the porous conductive network layer 30 is embedded into the electrically active material layer 20, the portion remaining on the surface of the electrically active material layer 20 of the porous conductive network layer 30 is a high density porous conductive network layer. (30A). Alternatively, the impregnated portion of the porous conductive network layer 30 is mixed with the electrical active material, binder and other external additives in the electrical active material layer 20, and thus the low density porous conductive network layer in the electrical active material layer 20. 30B may be provided.

In this case, as compared with the density of the porous conductive network layer 30 before the pressing process, the density of the porous conductive network layer 30A on the electrical active material layer 20 by the pressing process is a porous conductive network layer (laminating) The density of the porous conductive network layer 30B, which is increased than the density of 30 and embedded in the electrically active material layer 20, may be reduced in comparison thereto. As described above, according to the exemplary embodiment of the present invention, the density of the porous conductive network layer 30 on the surface of the electrically active material layer 30 and in the vicinity thereof is different from each other.

4A is a cross-sectional view showing an electrode assembly 200 according to another embodiment of the present invention, and FIG. 4B is a cross-sectional view showing a method of manufacturing the electrode assembly 200 according to an embodiment.

Referring to FIG. 4A, the electrode assembly 200 is stacked between the current collector 10 and the electrical active material layer 20, and has a base porous conductive network layer 40 partially embedded in the electrical active material layer 20. It is similar to the electrode assembly 100 shown in FIG. 1A except that it further includes.

The underlying porous conductive network layer 40 may be a metal foam, a carbon fiber, a metal long fiber layer or a combination thereof, preferably a metal long fiber layer or a carbon fiber, and more preferably a metal long fiber layer. The long metal fiber layer may have a nonwoven structure. A portion of the underlying porous conductive network layer 40 may be partially or entirely incorporated into the electrically active material layer 20 through a pressing process as described above.

When only a part of the underlying porous conductive network layer 40 is embedded into the electrically active material layer 20, a high density porous conductive network layer 40A exists between the current collector 10 and the electrically active material layer 20, The impregnated portion of the porous conductive network layer 40 may be mixed with the electrical active material, binder and other external additives in the electrical active material layer 20 to serve as the low density porous conductive network layer 40B. The impregnated portion of the ground porous conductive network layer 40 ensures a mechanical bond between the ground porous conductive network layer 40 and the electrically active material layer 20, and reduces the internal resistance of the electrically active material layer 20. have.

The metal long fibers may comprise, for example, any one or combination of stainless steel, aluminum, nickel, titanium and copper or alloys thereof. The nonwoven structure described above is a porous fiber structure formed by bending and entangled or entangled with each other using the fibrous properties of a plurality of metal long fibers.

Similar to the porous conductive network layer 30 described above, the metal long fibers constituting the base porous conductive network layer 40 may be segmented, and the average length of the segmented metal long fibers is 10 μm to It may have a length in the range of 100 mm. In addition, the metal long fibers may have a thickness in the range of 1 μm to 50 μm. Preferably, the metal long fibers may have a thickness of 1 μm to 10 μm. When the length of the metal long fibers is 1 μm or less, the strength of the metal long fibers may be weak, so that the metal long fibers may be easily broken in the entanglement process due to entanglement, and it may be difficult to form a conductive network. Since it is thick, it is difficult to be incorporated into the electrically active material layer, which may increase the thickness of the electrode, thereby increasing the distance between the anode and the cathode. In this case, the internal resistance may be increased in the movement of lithium ions.

Referring to FIG. 4B, the base porous conductive network layer 40L on the current collector 10 before applying the slurry layer 20L of the electrically active material on the current collector 10 to provide the electrode assembly 200. ) Can be formed. Thereafter, as described with reference to FIGS. 3B and 3C, the slurry layer 20L of the electrically active material is applied onto the underlying porous conductive network layer 40L, and again the porous conductive material is applied to the slurry layer 20L of the electrically active material. The network layer 30L can be laminated.

Thereafter, the resultant on which the porous conductive network layer 30L is stacked is dried, and the resultant is pressurized using a pressurizer such as a roll press, as shown in FIG. 3D, thereby forming the interior of the electrically active material layer (20 in FIG. 4A). An electrode assembly 200 may be fabricated in which a portion 30B of the furnace porous conductive network layer 30 and a portion 40B of the underlying porous conductive network layer 40B are embedded.

5 is a cross-sectional view showing an electrode assembly 300 according to another embodiment of the present invention.

Referring to FIG. 5, the electrode assembly 300 is illustrated in FIG. 4A except that the electrode assembly 300 has a plurality of stacked structures further including the second electrically active material layer 50 and the second porous conductive network layer 60. Similar to electrode assembly 200. The second electrically active material layer 50 is laminated on the main surface opposite to the main surface of the first porous conductive network layer 30 in contact with the first electrically active material layer 20.

In some embodiments, the underlying porous conductive network layer 40 and / or the second porous conductive network layer 60 may be omitted. In this case, an electrode assembly structure in which the porous conductive network layer 30 is completely embedded in the electrically active material layers 20 and 50 may be obtained. The embedded porous conductive network layer 30 may operate as an intermediate electrode layer.

In terms of the manufacturing method, the electrically active materials layers 20, 50 of the electrode assembly 300 may be provided in the form of a slurry, as described above, and the porous conductive network layers 30, 60 before drying the slurry. ) Can be laminated. Thereafter, a part of the porous conductive network layers 30 and 60 may be embedded into the electrically active material layers 20 and 50 through the pressing process. Accordingly, in the electrode structure 300, high density porous conductive network layers 30A, 40A, 60A and low density porous conductive network layers 30B, 40B, 60B may be provided.

In another embodiment, the drying process of the slurries may be performed sequentially according to the stacking order. For example, the slurry layer for forming the first electrically active material layer 20 and the first porous conductive network layer 30 are sequentially stacked, and then dried and subjected to a pressurization process to thereby form the first porous conductive network. At least a portion of the layer 30 may be embedded in the first electrically active material layer 20. Thereafter, the slurry layer for forming the second electrically active material layer 50 and the second porous conductive network layer 60 are sequentially stacked on the first porous conductive network 30, and a pressing process is performed to perform a second process. The second porous conductive network layer 60 may be embedded in the electrically active material layer 50. At this time, the first porous conductive network layer 30 is also incorporated into the second electrically active material layer 50.

According to the above-described embodiments, the porous conductive network layers 30 and 60 functioning as intermediate electrodes while increasing the thickness of the active material layer by stacking the plurality of electrically active material layers 20 and 50 to increase the charge and discharge capacity. As a result, the thickness dividing effect of the entire electrical active material layer is provided, and the internal resistance of the electrode assembly 300 is reduced, thereby improving the charging and discharging speed and efficiency. The thickness of the entire electrode assembly except for the current collector layer 10 may be 300 μm to 600 μm.

6 is an exploded view showing a battery 1000 using an electrode structure according to an embodiment of the present invention.

Referring to FIG. 6, the battery 1000 may be a general cylindrical battery. In order to increase the battery reaction area, the cathode and the anode 100A and 100B using the electrode structure described above may be packaged in the housing 800 in a roll structure formed alternately with each other. Tabs 150A and 150B may be coupled to one end of the electrode structures 100A and 100B, respectively. A plurality of tabs 150A and 150B may be repeatedly arranged at regular intervals to minimize resistance.

The electrode structures 100A, 100B comprise active electrode layers 15a, 15b comprising current collector layers 10a, 10b according to the suitable polarity described above, and an electrically active material layer having a corresponding polarity and a porous conductive network layer. The active electrode layers 15a and 15b may be stacked on both main surfaces of the current collector layer 10, respectively. A separator 500 may be disposed between the electrodes 100A and 100B for insulation between the cathode and the anodes 100A and 100B.

The separation membrane 500 may be, for example, a polymer microporous membrane, a woven fabric, a nonwoven fabric, a ceramic, an intrinsic solid polymer electrolyte membrane, a gel solid polymer electrolyte membrane, or a combination thereof. The intrinsic solid polymer electrolyte membrane may include, for example, a linear polymer material or a crosslinked polymer material. The gel polymer electrolyte membrane may be, for example, a combination of any one of a plasticizer-containing polymer containing a salt, a filler-containing polymer, or a pure polymer. The solid electrolyte layer is, for example, polyethylene, polypropylene, polyimide, polysulfone, polyurethane, polyvinyl chloride, polystyrene, polyethylene oxide, polypropylene oxide, polybutadiene, cellulose, carboxymethyl cellulose, nylon, polyacryl Ronitrile, polyvinylidene fluoride, polytetrafluoroethylene, copolymer of vinylidene fluoride and hexafluoropropylene, copolymer of vinylidene fluoride and trifluoroethylene, vinylidene fluoride and tetrafluoroethylene Copolymers of polymethyl acrylate, polyethyl acrylate, polyethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate, polyvinylacetate, and polyvinyl alcohol Made of any one or a combination thereof It may include a polymer matrix, additives and the electrolyte. The materials listed with respect to the separator 500 described above are exemplary, and the separator 500 is easy to change shape, and excellent in mechanical strength, so as not to be torn or cracked even when the electrode structures 100A and 100B are deformed. Materials that have suitable electronic insulation and yet have good ion conductivity can be selected.

The separator 500 may be a single layer film or a multilayer film, and the multilayer film may be a laminate of the same monolayer film or a stack of monolayer films formed of different materials. For example, the laminate may have a structure including a ceramic coating film on the surface of a polymer electrolyte film such as polyolefin. The thickness of the separator 500 may be 10 μm to 300 μm, preferably 10 μm to 40 μm, and more preferably 10 μm to 25 μm in consideration of durability, shutdown function, and battery safety.

The battery 1000 is electrically connected to the external electrode terminals 600 and 700 through the tabs 150A and 150B coupled to the electrode structures 100A and 100B, respectively. Within the housing 800 a suitable aqueous electrolyte solution or salt comprising potassium chloride (KOH), potassium bromide (KBr), potassium chloride (KCL), zinc chloride (ZnCl ₂ ) and sulfuric acid (H ₂ SO ₄ ) or LiClO ₄ , Non-aqueous electrolytes such as ethylene carbonate, propylene carbonate, dimethyl carbonate, and diethyl carbonate containing lithium salts such as LiPF ₆ are absorbed by the electrode structures 100A and 100B and / or the separator 500, so that the battery 1000 Can be completed. Although not shown, a suitable battery management system for controlling stability and / or power supply characteristics during use of the battery 1000 may additionally be combined.

The above-described electrode assembly may be selected in various volumes in order to adjust the capacity of the battery in addition to the illustrated cylindrical battery. In addition, according to an embodiment of the present invention, due to the ease of forming the porous conductive network, three-dimensional deformation by methods such as stacking, bending and winding can be provided a battery having a variety of shapes other than the above-described cylindrical battery have.

In addition, the battery according to an embodiment of the present invention is applied as a small battery that can be attached to clothes, bags, etc., or may be integrated with the cloth of clothes and bags, high capacity and / or high power is possible to provide a power source or power storage of the vehicle It can be applied as a medium-large battery for.

7 is a graph showing a charging method including a plurality of charging steps according to an embodiment of the present invention.

Referring to FIG. 7, the battery may be charged by, for example, four steps. The battery used is a half cell having an electrode assembly structure according to one embodiment of the invention disclosed with reference to FIG. 1.

In the first stage (P1), 60 C-rate was charged and 35% of the nominal capacity was filled for 1 minute. Subsequently, in the next step (P2), charging for 1 minute 30 seconds with 20 C-rate resulted in a charge of 65%. In the next step (P3), charging for 5 minutes with 5 C-rate resulted in an 85% capacity. In the last step (P4), charging was carried out for 7 minutes at 1 C-rate, and the battery was charged up to 97% close to 100% of the nominal capacity.

According to this embodiment, 97% of the nominal capacity can be charged in a total time of 12 minutes and 30 seconds, so that the charging time can be shortened. The above embodiment is divided into four steps to perform the charging, but this is exemplary, and the present invention is not limited thereto. For example, the filling step may be divided into two, three, or five or more steps, while gradually decreasing the C-rate. In addition, the C-rate of the initial fast charging step may be performed at an arbitrary value of 100 C-rate or less, and the C-rate of the final slow charging step may be performed at an arbitrary value of 0.1 rate or more.

As such, charging the remaining capacity by dividing a plurality of circuits while reducing the charging C-rate has an advantage of shortening the charging time while charging to have a value as close as possible to the nominal capacity. Such a charging method may be accomplished in software, hardware, or a combination thereof, and may be implemented through the aforementioned battery managing system.

Although the above-described embodiment is disclosed in terms of the charging method, the discharge method may be similarly implemented. That is, the discharge of the battery can be divided into a plurality of times. For example, in the initial discharge step, the C-rate can be increased, and the C-rate can be gradually decreased to discharge through various steps. By performing the discharging step in this way, a large amount of energy can be obtained from the battery for a quick time.

The above-described charge / discharge features may be combined with a smart grid system to implement an efficient power management system. For example, it is possible to operate the storage and emission of power in one cell regardless of the load characteristics of various power sources such as nuclear power, solar cells, hydropower, or various power consumers such as factories and homes.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be clear to those who have knowledge.

Claims (5)

Charging a portion of the nominal capacity of the battery with the first charging C-rate; And
Charging the remaining capacity of the battery with a second charge C-rate lower than the first charge C rate; or
Discharging a portion of the nominal capacity of the battery with a first discharge C-rate; And
Charging the discharge capacity of the battery with a second discharge C-rate lower than the first discharge C rate. The method of claim 1,
The charging or discharging method is a charging or discharging method of a battery, characterized in that carried out coupled to the smart grid. The method of claim 1,
The battery includes an electrode assembly of a positive electrode and a negative electrode,
At least one of the electrode assembly of the positive electrode and the negative electrode,
Collecting house;
An electrical active material layer laminated on the current collector; And
It is laminated on the main surface opposite the main surface of the electrical active material layer in contact with the current collector and provided as an upper surface exposed on the electrical active material layer, at least a part of which is embedded into the electrical active material layer to mechanically interact with the electrical active material layer. A method of charging or discharging a battery comprising a first porous conductive network layer to secure a bond or a second porous conductive network layer embedded in the electrically active material layer. The method of claim 1,
The battery includes an electrode assembly of a positive electrode and a negative electrode,
At least one of the electrode assembly of the positive electrode and the negative electrode,
Collecting house;
An electrical active material layer laminated on the current collector; And
And a base porous conductive network layer stacked between the current collector and the electrical active material layer and at least partially embedded in the electrical active material layer. An electrode assembly having a polarity of one of a positive electrode and a negative electrode,
Collecting house;
An electrical active material layer laminated on the current collector; And
And an underlying porous conductive network layer stacked between the current collector and the electrically active material layer and at least partially embedded in the electrically active material layer.

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