Insulation composition, electrode comprising an insulation layer derived therefrom and secondary battery comprising the same

Abstract

An insulating composition according to one embodiment of the present invention is an insulating composition comprising 35% by weight or less of a solid content relative to the total weight, wherein the solid content comprises inorganic particles, a polymer material, and clay, wherein the clay has positive and negative charges distributed within the particles and is included in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of the solid content, and the polymer material comprises a polymer containing functional groups. The insulating composition has low viscosity at high shear rates and high viscosity at low shear rates, resulting in excellent coating processability, and can form a narrow insulating width by minimizing sliding portions when forming an insulating layer, thereby preventing the problem of the positive / negative capacity ratio being reversed that may occur due to sliding portions.

Description

Technology Field

[0001] The present specification discloses technology relating to an insulating composition, an electrode comprising an insulating layer derived therefrom, and a secondary battery comprising the same. Background Technology

[0003] With the recent increase in technological development and demand for mobile devices, the demand for batteries as energy sources is rapidly rising, and accordingly, various studies are being conducted on batteries capable of meeting diverse requirements. In particular, active research is being conducted on secondary batteries that possess high energy density and excellent lifespan and cycle characteristics to serve as power sources for these devices.

[0004] A secondary battery comprises a positive electrode containing a positive active material capable of inserting / extracting lithium ions, a negative electrode containing a negative active material capable of inserting / extracting lithium ions, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The positive electrode and the negative electrode have a structure in which an electrode active material layer is formed on one side of an electrode current collector or on the positive electrode. Recently, technology has been developed to form an insulating layer on the outer edge of the electrode active material layer to improve the stability of the electrode. By forming an insulating layer on the outer edge of the electrode active material layer, the electrode active material layer can be protected from heat generated during electrode operation, and insulation between electrodes can be enhanced.

[0005] Conventional electrode insulating layers were generally formed using binders with insulating properties. However, since binders have poor heat resistance, conventional insulating layers made of binders suffer from reduced adhesion under high-temperature conditions during battery operation, which consequently compromises battery safety. To address this issue, a technology has been proposed to improve the heat resistance of the insulating layer by adding inorganic particles to a coating composition for electrode insulation.

[0006] Meanwhile, in addition to the effects and functions of ensuring basic safety, such as preventing short circuits between electrodes, the electrode insulating layer can also have the function of minimizing sliding portions on the sides that inevitably occur during the electrode slurry coating and drying process. Accordingly, methods to control the coating process during insulating composition and slurry coating are being developed to minimize sliding portions; however, controlling process conditions has limitations, and there are issues such as high costs associated with replacing equipment or changing the process. Therefore, it is necessary to develop an insulating composition that can solve these problems. The problem to be solved

[0008] In one aspect of the present specification, the aim is to provide an insulating composition that can improve viscosity characteristics by including a functional group-containing polymer and clay with positive and negative charges distributed therein in a specific amount, in an insulating composition having a solid content of less than or equal to a specific value.

[0009] In another aspect of the present specification, by including an insulating layer derived from the insulating composition, the insulating layer is easy to implement in thickness, so even when the electrode composite layer thickness is thick due to a high loading amount, the insulating width is thin and the formation of a sliding portion is minimized.

[0010] In another aspect of the present specification, the aim is to provide a secondary battery that includes the electrode, thereby forming an insulating layer stably while maintaining a high loading amount, and thus securing high capacity while preventing the problem of the positive / negative capacity ratio (N / P ratio) being reversed due to the sliding portion. means of solving the problem

[0012] [1] In one aspect, an insulating composition is provided that contains 35% by weight or less of solids relative to the total weight, wherein the solids include inorganic particles, a polymer material and clay, the clay has positive and negative charges distributed within the particles and is included in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of solids, and the polymer material includes a polymer containing functional groups.

[0013] [2] In the above [1], the solid content may be included in an amount of 27% by weight or less relative to the total weight of the insulating composition.

[0014] [3] In the above [1] and / or [2], the clay may be included in an amount of 0.05 to 5 parts by weight per 100 parts by weight of solids.

[0015] [4] In at least one of [1] to [3] above, the inorganic particles may be included in an amount of 60 to 92 parts by weight per 100 parts by weight of solids, and the polymer material may be included in an amount of 5 to 20 parts by weight per 100 parts by weight of solids.

[0016] [5] In at least one of [1] to [4] above, the inorganic particles may comprise one or more selected from the group consisting of boehmite (AlOOH), aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2), alumina (Al2O3) and zirconia (ZrO2).

[0017] [6] In at least one of [1] to [5] above, the functional group-containing polymer may include one or more functional groups selected from the group consisting of carboxyl groups, ester groups, amide groups and cyano groups.

[0018] [7] In at least one of [1] to [6] above, the polymer material further comprises a binder, and the binder may comprise one or more selected from the group consisting of styrene-butadiene copolymer, acrylate styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin and polyvinyl alcohol.

[0019] [8] In at least one of [1] to [7] above, the clay may be a plate-shaped particle and may comprise one or more selected from the group consisting of hectorite, saponite and bentonite.

[0020] [9] In at least one of [1] to [8] above, the insulating composition may further include an aqueous solvent.

[0021]

[10] In at least one of [1] to [9] above, the insulating composition further comprises a hydrophobic additive, and the hydrophobic additive may comprise activated carbon.

[0023]

[11] In another aspect, an electrode is provided comprising: a current collector; an electrode composite layer provided on a part of the current collector and comprising an electrode active material; and an insulating layer disposed on a current collector adjacent to the electrode composite layer but not on the current collector where the electrode composite layer is not provided; wherein the insulating layer comprises inorganic particles, a polymer material and clay, and the clay has positive and negative charges distributed within the particles and is included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the insulating layer, and the polymer material comprises a functional group-containing polymer.

[0024]

[12] In the above

[11] , the electrode active material is a negative electrode active material, and the negative electrode active material may comprise one or more selected from the group consisting of silicon-based active materials, carbon-based active materials and silicon-carbon composite active materials.

[0025]

[13] In the above

[11] and / or

[12] , the electrode composite layer may further include a binder and a conductive material.

[0027]

[14] In another aspect, a secondary battery comprising at least one of the electrodes

[11] to

[13] is provided. Effects of the invention

[0029] An insulating composition according to one aspect of the present specification comprises a functional group-containing polymer and clay with positive and negative charges distributed therein, in an insulating composition having a solid content of less than or equal to a specific value, and can improve viscosity characteristics, thereby improving storage stability and coating processability of the composition.

[0030] An electrode according to another aspect of the present specification includes an insulating layer derived from the insulating composition, so that the insulating layer is easy to implement in thickness, and even when the electrode composite layer thickness is thick due to high loading amount, the insulating width is thin and the formation of sliding portions is minimized, making high loading possible.

[0031] A secondary battery according to another aspect of the present specification includes the electrode, thereby forming an insulating layer stably with a high loading amount, so that high capacity can be secured and the problem of the positive / negative capacity ratio (N / P ratio) being reversed due to the sliding part can be prevented. Specific details for implementing the invention

[0033] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0034] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0035] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0036] In this specification, when a part is described as including a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0037] In this specification, the description "A and / or B" means A, or B, or A and B.

[0038] In this specification, "%" means weight percent unless otherwise explicitly indicated.

[0039] In this specification, D 50 In the particle size distribution curve, it refers to the particle size corresponding to 50% of the cumulative volume, and D 90 In the particle size distribution curve, it refers to the particle size corresponding to 90% of the cumulative number. The above D 50 and D 90 For example, it can be measured using the laser diffraction method. The laser diffraction method generally enables the measurement of particle sizes ranging from the submicron range to several millimeters, and can obtain results with high reproducibility and high resolution.

[0041] In this specification, each of the insulating composition, electrode, and secondary battery comprises one or more of the technical features and / or technical configurations described below, and these technical features and / or technical configurations may be combined in various ways.

[0043] 1. Insulating composition according to the first aspect

[0044] An insulating composition according to the first aspect is an insulating composition comprising 35% by weight or less of a solid content relative to the total weight, wherein the solid content comprises inorganic particles, a polymer material, and clay, wherein the clay has positive and negative charges distributed within the particles and is included in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of the solid content, and the polymer material comprises a functional group-containing polymer.

[0046] In the first aspect, the insulating composition is characterized by having a solid content of 35 weight% or less, and preferably, 33 weight% or less, 30 weight% or less, 27 weight% or less, or 25 weight% or less.

[0047] The solid content in the insulating composition can be a factor that determines the viscosity of the composition, and can be determined by considering the wet thickness when forming the insulating layer, the ease of discharge from the coating nozzle, and the content of components to be included in the insulating layer. However, if the solid content is higher than the above range, problems such as the nozzle clogging when the insulating composition is discharged from the coating nozzle or the coating thickness of the insulating layer being uneven may occur, so it is desirable to lower the solid content as much as possible within the aforementioned range.

[0049] In the first aspect, the insulating composition is characterized by comprising inorganic particles, clay, and a polymer material. Generally, the insulating composition can be placed on the unoccupied portion of the side of the electrode active material layer on the electrode current collector to obtain effects such as preventing short circuits between electrodes and preventing unnecessary side reactions at the electrode ends. To this end, inorganic particles are included, and a polymer material is included to appropriately place the inorganic particles in the insulating layer and to provide retention. One or more types of the polymer material may be included to impart various functions to the composition, for example, a material that functions as a binder to provide bonding strength and a material that functions to achieve a wet thickness by increasing viscosity may be added.

[0050] The above insulating composition is designed to provide a function of lowering viscosity by reducing the solid content to facilitate easy discharge from the coating equipment and uniformity in the formation of the insulating layer thickness during coating, while also requiring efforts to increase viscosity to increase the thickness in a wet state after discharge from the coating equipment to the current collector. To this end, the insulating composition may include a polymer material, and is characterized by including a functional group-containing polymer as the polymer material.

[0051] The above functional group-containing polymer can function to increase the viscosity within the composition, thereby offering the advantage of making it easier to achieve a wet thickness. However, when the above functional group-containing polymer is added, the viscosity increases, and this increase in viscosity may cause problems when the insulating composition is discharged from the coating equipment.

[0052] Accordingly, the inventors propose an insulating composition comprising clay in which positive and negative charges are distributed within the particles, in order to achieve viscosity characteristics such that the viscosity is maintained at a level as low as possible when the composition is discharged from a coating equipment, and the viscosity is maintained at a level as high as possible on a current collector after discharge from the equipment.

[0054] 1) Clay

[0055] In the first aspect, the clay is characterized by having positive and negative charges distributed within the particles and being included in the insulating composition in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of solid content.

[0056] The clay is included in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of solid content. If an amount less than 0.01 parts by weight is included, it is difficult to achieve viscosity characteristics because it is difficult to exhibit an effect sufficient to crosslink the functional group-containing polymer through bonding by electrical attraction, which will be described later. If an amount greater than 10 parts by weight is added, the bonding by electrical attraction dissociates at a high shear rate, but then reactivates as the shear force is released and changes to a low shear rate, causing the bonding to increase rapidly. Additionally, this may cause the problem of the piping becoming clogged as the insulating composition is discharged after being mixed in the coating equipment. Accordingly, preferably, the clay may be included in an amount of 0.05 parts by weight or more, 0.08 parts by weight or more, or 0.1 parts by weight or more, and may also be included in an amount of 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, or 5 parts by weight or less.

[0057] The clay may be plate-shaped particles, for example, may include a 2:1 type clay mineral in which the ratio of tetrahedral sheets to octahedral sheets is 2:1, and may consist of two or more layers stacked in a form in which octahedral sheets are located between tetrahedral sheets. In the clay, positive charges (δ+) may be distributed on the edge portions of the plates on the surface of the particles, and negative charges (δ-) may be distributed on the surface portions inside the edges of the plates.

[0058] As positive and negative charges are distributed in the clay, when included with a polymer material, for example, a polymer containing functional groups, the carboxyl groups may be ionized due to the charges distributed separately within the clay particles, and the cations separated therefrom may be adsorbed into the interlayer space of the plate, and this space may contain water.

[0059] Since the ionized carboxyl group is an anion, it can form bonds through electrical attraction with positive charges distributed at the edges of the plate, for example, through polar interaction or dipole interaction. This bond can exert an effect similar to cross-linking between functional group-containing polymer molecules, and bonding and dissociation can occur freely and reversibly depending on the applied external force; through this reversible dissociation and bonding, a desired level of viscosity can be achieved according to the shear rate. This interaction between the clay and the functional group-containing polymer can be expressed more strongly when the solid content is 35 weight% or less, and when the solid content is relatively low, the reversible reaction of bonding and dissociation can be carried out more smoothly.

[0060] The above clay has an average particle size (D 50The particle size may be 10 nm to 2 μm, preferably 20 nm or more, 25 nm or more, or 30 nm or more, and 1.8 μm or less, 1.7 μm or less, or 1.5 μm or less. In this case, the average particle size D50 may be measured by the laser diffraction method on a dispersion in which 1.1 weight% of the clay is dispersed in water.

[0061] The clay may be, for example, a smectite-based clay mineral. The clay may preferably comprise one or more selected from the group consisting of hectorite, saponite, and bentonite. Additionally, the hectorite, saponite, and bentonite may be commercially available as laponite (BYK), sumecton (Kunimine Industries), and cloisite (BYK), respectively.

[0063] 2) Polymer materials

[0064] In the first aspect, the insulating composition comprises a polymer material, and the polymer material comprises a functional group-containing polymer. The functional group-containing polymer may include one or more functional groups selected from the group consisting of carboxyl groups, ester groups, amide groups, and cyano groups.

[0065] For example, the functional group-containing polymer may comprise one or more selected from the group consisting of carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylfluran, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. Preferably, it may comprise one or more selected from the group consisting of carboxymethyl cellulose, hydroxypropylmethyl cellulose, and hydroxypropyl cellulose. The functional group-containing polymer may function as a thickener in an insulating composition.

[0066] The above polymer material may also further include a binder, and as a representative example, the binder may include one or more selected from the group consisting of styrene-butadiene copolymer, acrylate styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, and polyvinyl alcohol. Among these, it is preferable to use a styrene-butadiene copolymer, an acrylate styrene-butadiene copolymer, an acrylonitrile-butadiene copolymer, an acrylonitrile-butadiene-styrene copolymer, or a mixture thereof.

[0067] The above polymer material may be included in the insulating composition in an amount of 5 to 20 parts by weight relative to 100 parts by weight of solid content, preferably 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, or 10 parts by weight or more, and may also be 18 parts by weight or less, 16 parts by weight or less, 15 parts by weight or less, or 14 parts by weight or less.

[0068] The above content may be the total weight of the binder and the functional group-containing polymer, and the functional group-containing polymer may be 1 part by weight or more, 2 parts by weight or more, or 3 parts by weight or more per 100 parts by weight of solid content, and may also be 8 parts by weight or less, 7 parts by weight or less, or 6 parts by weight or less. Within the above range, the thickening effect of the functional group-containing polymer can have an appropriate influence on the insulating composition, and if it falls outside that range, it may be difficult to control viscosity at high or low shear rates. At this time, the binder may include the remainder excluding the content of the functional group-containing polymer within the content range of the polymer material.

[0070] 3) Inorganic particles

[0071] In the first aspect, the insulating composition is characterized by including inorganic particles.

[0072] The above insulating composition is placed on the side of the active material layer on the electrode-free portion to prevent high-risk events, such as thermal runaway or explosion caused by a short circuit between electrodes when the battery operates abnormally; therefore, it is essential for it to possess the characteristic of withstanding high temperatures without melting. Accordingly, this problem has been improved by incorporating inorganic particles with heat-resistant properties into the insulating layer, whereas conventional insulating layers previously used only binders.

[0073] The above inorganic particles can primarily perform the function of increasing heat resistance. Since the above inorganic particles do not soften or melt even at high temperatures, for example, 900°C or higher, if such inorganic particles are included in the insulating layer, electrode insulation can be maintained even at very high temperatures.

[0074] The above inorganic particles may include, for example, one or more selected from the group consisting of boehmite (AlOOH), aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2), alumina (Al2O3), and zirconia (ZrO2). Preferably, boehmite may be applied, in which case superior heat resistance can be secured and excellent dispersibility can be achieved, so that heat resistance properties can be obtained uniformly throughout the insulation layer, and due to the presence of hydroxyl groups included in the above inorganic particles, the ability to maintain adhesion even after electrolyte impregnation can be excellent.

[0075] D of the above-mentioned inorganic particles 50 The silver may be 0.1 μm to 5.0 μm, preferably 0.1 μm to 3.0 μm, more preferably 0.3 μm or more, 0.5 μm or more, and also 2.0 μm or less, 1.5 μm or less. D of the inorganic particles 50 When the above range is satisfied, the aggregation of the inorganic particles within the insulating coating composition is minimized when forming the insulating layer, thereby enabling the formation of an insulating layer having a uniform thickness and surface.

[0076] The above inorganic particles may be included in an amount of 60 to 92 parts by weight per 100 parts by weight of solid content in the insulating composition, preferably 65 parts by weight or more, 70 parts by weight or more, or 75 parts by weight or more, and may also be 91 parts by weight or less, 90 parts by weight or less, 89 parts by weight or less, or 88 parts by weight or less. When the content of the above inorganic particles satisfies the above range, the occurrence of aggregation of inorganic particles within the insulating composition is minimized when forming the insulating layer, thereby maintaining the viscosity of the composition appropriately and forming an insulating layer having a uniform thickness and surface.

[0078] 4) Hydrophobic additives

[0079] In the first aspect, the insulating composition may further include the hydrophobic additive, and the hydrophobic additive may include activated carbon.

[0080] The above hydrophobic additive has a specific surface area (BET) of 700 m² 2 / g to 3,000 m 2 It may be in the range of / g, preferably 750 m 2 / g or more, 800 m 2 / g or more, 850 m 2 / g or more, 900 m 2 / g or more, or 950 m 2 It can be greater than / g, and 2,700 m 2 / g or less, 2,500 m 2 / g or less, 2,200 m 2 / g or less, 2,000 m 2 / g or less, 1,800 m 2 / g or less, or 1,500 m 2 It may be less than / g. If the specific surface area of ​​the above hydrophobic additive satisfies the above range, the problem of the maximum height becoming higher than the active material layer when forming the insulating layer can be prevented.

[0081] The above-mentioned hydrophobic additive may be a carbon-based additive, for example, activated carbon. The activated carbon is composed of graphite and may have a porous structure connected by carbon-carbon bonds. The activated carbon has a porous structure with a large specific surface area, and can achieve high surface tension by adsorbing SBR binders, etc., within the pores even in small amounts.

[0082] The above hydrophobic additive has a specific surface area of ​​700 m² 2 / g to 1,500 m 2 A first additive having / g; and a specific surface area of ​​1,500 m² 2 / g to 3,000 m 2 It may include one or more of the second additives having a specific surface area of ​​700 m² / g. For example, the first additive has a specific surface area of ​​700 m² 2 / g to 1,500 m 2 / g, preferably 1,000 m 2 / g to 1,250 m 2 It can be / g, and the average particle size (D 50 ) may be 25 μm to 60 μm, preferably 35 μm to 45 μm. In addition, the second additive has a specific surface area of ​​1,500 m² 2 / g to 2,200 m 2 / g, preferably 1,600 m 2 / g to 2,100 m 2 It can be / g, and the average particle size (D 50 ) can be 2 μm to 10 μm, preferably 3 μm to 6 μm.

[0083] Various methods can be applied to increase the hydrophobicity of the above hydrophobic additive, for example, by using activated carbon with a high specific surface area, heat treatment, for example at 500°C, or acid or base treatment.

[0085] 5) Others

[0086] The insulating composition may include a solvent, and the solvent may be an aqueous solvent, for example, the aqueous solvent may be water (H2O).

[0087] The insulating composition may not substantially exhibit electrical conductivity. For example, the insulating composition may have a volume resistance of 1,000 Ω·cm or more, or in the range of 1,000 Ω·cm to 5,000 Ω·cm.

[0088] The insulating composition may have a surface tension of 70 mN / m or more. The insulating composition may have a high surface tension when it contains an appropriate amount of a hydrophobic additive, for example, 70 mN / m to 100 mN / m, or 70 mN / m to 80 mN / m.

[0090] 2. Insulating composition according to the second aspect

[0091] An insulating composition according to the second aspect is an insulating composition comprising a solid content of 35 weight% or less based on the total weight, wherein the solid content comprises inorganic particles and polymer materials, and has a shear rate of 0.0251 s -1 The viscosity at is 4,000 mPa·s or higher, and the shear rate is 251 s -1 It can be characterized by having a viscosity of 400 mPa·s or less.

[0092] The viscosity according to the shear rate above may be measured at room temperature, for example, 20°C to 30°C, 21°C to 27°C, 22°C to 25°C, 23°C to 25°C, preferably 23°C.

[0093] The insulating composition according to the second aspect above may have substantially the same components as the insulating composition according to the first aspect, and the differences from the insulating composition according to the first aspect are described below, and unless otherwise noted, may share the characteristics and effects of the insulating composition according to the first aspect.

[0095] In a second aspect, the insulating composition comprises inorganic particles and polymer materials as the solid component, and has a shear rate of 0.0251 s -1 The viscosity at is 4,000 mPa·s or higher, and the shear rate is 251 s -1 It is characterized by having a viscosity of 400 mPa·s or less.

[0096] The above insulating composition is characterized by the fact that its viscosity can be controlled within a specific range according to the shear rate. In the case of the insulating composition, low viscosity is required in coating equipment to facilitate smooth dispensing and improve processability, while high viscosity is required when forming an insulating layer on a current collector after dispensing to maintain a thick wet thickness and form a narrow insulating width. The insulating composition according to the second aspect reflects such characteristics, with a shear rate of 0.0251 s -1 The viscosity at is 4,000 mPa·s or higher, and the shear rate is 251 s -1 By satisfying the condition that the viscosity is 400 mPa·s or less, it is possible to obtain both advantages of easy discharge during coating and the realization of a thick and narrow insulating layer as described above.

[0097] The above insulating composition preferably has a shear rate of 0.0251 s -1The viscosity may be 4,300 mPa·s or more, 4,500 mPa·s or more, 4,700 mPa·s or more, 4,900 mPa·s or more, 5,100 mPa·s or more, or 5,200 mPa·s or more, and may also be 200,000 mPa·s or less, 180,000 mPa·s or less, or 175,000 mPa·s or less. Additionally, the insulating composition preferably has a shear rate of 251 s -1 The viscosity at may be 395 mPa·s or less, 390 mPa·s or less, 380 mPa·s or less, 375 mPa·s or less, or 370 mPa·s or less, and may also be 70 mPa·s or more, 80 mPa·s or more, 90 mPa·s or more, 100 mPa·s or more, or 120 mPa·s or more. The above viscosity ranges for each shear rate are ranges for achieving coating processability (ease of discharge from the coating nozzle) and the wet thickness of the insulating layer, and it is desirable to control the types and content of components included in the insulating composition and the solid content to satisfy these conditions.

[0098] The insulating composition further comprises clay, wherein the clay has positive and negative charges distributed within the particles and is included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of solid content, and the polymer material may comprise a functional group-containing polymer. The characteristics regarding the clay and the polymer material are the same as those in the insulating composition according to the first aspect.

[0099] The viscosity range of the insulating composition according to the shear rate can be determined according to the solid content in the composition, the type and content of the functional group-containing polymer, and whether and the content of clay are added, as described in the insulating composition according to the first aspect.

[0100] The insulating composition described above may induce bonding and dissociation due to electrical attraction between the two materials by introducing clay in which both positive and negative charges are distributed within the particles, along with a polymer containing functional groups capable of ionizing into cations and anions. For example, at high shear rates, the external force applied to the polymer containing functional groups and the clay in the composition is strong, causing the bonding due to electrical attraction to dissociate, thereby maintaining a relatively low viscosity. Furthermore, at low shear rates, the applied external force is not strong enough to dissociate the bonding due to electrical attraction between the two materials, so they may function as if they are cross-linked, thereby maintaining a high viscosity.

[0102] 3. Electrode according to the third aspect

[0103] According to a third aspect, an electrode is provided comprising: a current collector; an electrode composite layer provided on a part of the current collector and comprising an electrode active material; and an insulating layer disposed on a current collector adjacent to the electrode composite layer but not on the current collector where the electrode composite layer is not provided; wherein the insulating layer comprises inorganic particles, a polymer material, and clay, the clay having positive and negative charges distributed within the particles, and is included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the insulating layer, and the polymer material comprises a functional group-containing polymer.

[0104] The electrode is characterized by comprising an insulating layer derived from an insulating composition according to a first aspect and / or a second aspect, wherein the insulating layer may be substantially identical to the solid component of the insulating composition and the content of the component.

[0105] The types, characteristics, and content of the materials constituting the insulating layer, such as inorganic particles, polymer materials, and clay, may be substantially the same as those described in the insulating composition according to the first and / or second aspects, and thus a specific description thereof is omitted.

[0106] According to a third aspect, the electrode composite layer comprises an electrode active material and may further comprise a binder and a conductive material. The electrode active material may be a positive electrode active material or a negative electrode active material, preferably a negative electrode active material, and the negative electrode active material may comprise one or more selected from the group consisting of silicon-based active materials, carbon-based active materials, and silicon-carbon composite active materials.

[0108] 1) Cathode

[0109] When the above electrode is a negative electrode, it includes a negative electrode current collector and a negative electrode composite layer located on the negative electrode current collector, and the negative electrode composite layer may include a negative electrode active material, a binder, and a conductive material.

[0110] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, heat-treated carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used.

[0111] The above-mentioned negative electrode current collector can typically have a thickness of 3 μm to 500 μm, and preferably can have a thickness of 300 μm or less, 200 μm or less, 100 μm or less, or 80 μm or less. Fine irregularities may be formed on the surface of the current collector to strengthen the bonding force with the negative electrode active material.

[0112] The above-mentioned cathode current collector can be used in various forms, such as, for example, a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric, etc. Additionally, the above-mentioned cathode current collector may be a metal foil, or a composite film in which metal is deposited on at least one surface of a resin may be used.

[0113] The above-mentioned negative electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, for example, carbon materials such as artificial graphite, natural graphite, Kish graphite, pyrolytic carbon, meso-carbon microbeads, mesophase pitches, petroleum or coal tar pitch-derived cokes, mesophase pitch-based carbon fiber, graphitized carbon fiber, amorphous carbon, softened carbon, or hardened carbon; (semi)metallic materials capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; SiO b (0 <b≤2), SnO2, 바나듐 산화물, 리튬 바나듐 산화물과 같이 리튬을 도프 및 탈도프할 수 있는 (준)금속 산화물 재료; Si-C 복합체 또는 Sn-C 복합체과 같은 이종 복합 재료; 또는 금속 리튬 박막 등을 들 수 있으며, 이들 중 어느 하나 또는 둘 이상의 혼합물이 사용될 수 있다.

[0114] Preferably, the negative electrode active material may comprise one or more selected from the group consisting of silicon-based active materials, carbon-based active materials, and silicon-carbon composite active materials; more preferably, the carbon-based active material may comprise one or more selected from the group consisting of artificial graphite, natural graphite, softened carbon, and hardened carbon, and the silicon-based active material may comprise pure Si particles and / or SiO₂ b (0 <b≤2)를 포함할 수 있으며, 상기 실리콘-탄소 복합계 활물질은 Si-C 복합체를 포함할 수 있다. 또한, 상기 음극 활물질은 상기한 물질들 중에서 2 이상이 혼합된 혼합 활물질이 적용될 수도 있다.

[0115] The above-mentioned negative electrode active material may be included in an amount of 60% to 99% by weight based on the total weight of the negative electrode active material layer, preferably in an amount of 70% or more, 80% or more, 85% or more, or 90% or more by weight, and may also be included in an amount of 98% or less, 97% or less by weight, or 95% or less by weight.

[0116] The above binder is a component that assists in the bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1% to 10% by weight based on the total weight of the negative active material layer, and can be included in an amount of 0.2% or more, 0.3% or more, or 0.5% or more by weight, and can also be included in an amount of 8% or less, or 5% or less by weight. Examples of such binders may include one or more selected from the group consisting of styrene-butadiene copolymer, acrylate styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, and polyvinyl alcohol. Among these, it may include one or more selected from the group consisting of styrene-butadiene copolymer, acrylate styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, cellulose acetate butyrate, cellulose acetate propionate, cyanoethylfluran, cyanoethyl polyvinyl alcohol, cyanoethyl cellulose, and cyanoethyl sucrose. Preferably, it is preferable to use carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, or a mixture thereof.

[0117] The above conductive material is a component for further improving the conductivity of the negative electrode active material and may be added in an amount of 10% by weight or less, preferably 5% by weight or less, 3% by weight or less, 2% by weight or less, or 1% by weight or less, based on the total weight of the negative electrode composite layer, and may also be included in an amount of 0.01% by weight or more, 0.05% by weight or more, 0.08% by weight or more, 0.1% by weight or more, or 0.3% by weight or more. Such conductive material is not particularly limited as long as it has conductivity without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. may be used.

[0118] The above cathode composite layer may be manufactured by applying a cathode slurry composition, prepared by dissolving or dispersing a cathode active material and optionally a binder and a conductive material in a solvent, onto a cathode current collector and drying it, or by casting the cathode slurry composition onto a separate support and then laminating the film obtained by peeling it off from the support onto a cathode current collector.

[0120] 2) Anode

[0121] When the above electrode is a positive electrode, it includes a positive current collector and a positive composite layer located on the positive current collector, and the positive composite layer may include a positive active material, a binder, and a conductive material.

[0122] The above positive current collector may be conductive without causing chemical changes in the battery, and is not particularly limited. For example, the above positive current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.

[0123] The above positive current collector can typically have a thickness of 3 μm to 500 μm, and preferably can have a thickness of 300 μm or less, 200 μm or less, 100 μm or less, or 80 μm or less. Fine irregularities may be formed on the surface of the current collector to strengthen the bonding force with the positive active material.

[0124] The above positive current collector can be used in various forms, such as, for example, a film, a sheet, a foil, a net, a porous body, a foam, a nonwoven fabric, etc. Additionally, the above positive current collector may be a metal foil, or a composite film in which metal is deposited on at least one surface of a resin may be used.

[0125] The above-mentioned positive active material is a compound capable of reversible intercalation and deintercalation of lithium, and may include a lithium transition metal compound containing one or more selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe).

[0126] For example, it may include a lithium metal oxide containing lithium and one or more metals such as cobalt, manganese, nickel, or aluminum. More specifically, the lithium metal oxide may be a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), or a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2(0 <Y<1), LiMn 2-Z Ni ZO4 (O < Z < 2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O2(0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O2(0 <Y2<1), LiMn 2-Z1 Co Z1 O4 (O < Z1 < 2), etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O2(0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li(Ni p1 Co q1 Mn r1 )2O4(0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2) etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2 )O2(M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r2, and s2 are the atomic fractions of independent elements, respectively, 0 < p2 < 1, 0 < q2 < 1, 0 < r2 < 1, 0 < s2 < 1, p2 + q2 + r2 + s2 = 1), etc.), lithium iron phosphate (e.g., Li 1+a Fe 1-x M x (PO 4-b )X b Examples include (M is one or more selected from Al, Mg and Ti, X is one or more selected from F, S and N, -0.5≤a≤0.5, 0≤x≤0.5, 0≤b≤0.1), and any one or more of these compounds may be included.

[0127] The above-mentioned positive active material may comprise 80% to 99% by weight based on the total weight of the positive composite layer, preferably 85% or more, 88% or more, 90% or more, 92% or more, 93% or more, or 95% or more by weight, and may also comprise 98.5% or less by weight, 98% or less by weight, or 97.5% or less by weight. When included within the above range, it may be desirable in terms of increasing the capacity and energy density of the electrode, as well as optimizing the functions of the auxiliary materials, such as the conductive material and binder.

[0128] The above conductive material is a component for further improving the conductivity of the positive electrode active material, and such conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, carbon black powder such as acetylene black, ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; conductive fibers such as carbon fibers or metal fibers; conductive powders such as carbon fluoride powder, aluminum powder, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used. Specifically, to ensure uniform mixing of the conductive material and to improve conductivity, it may include one or more selected from the group consisting of activated carbon, graphite, carbon black, and carbon nanotubes (CNT).

[0129] The conductive material may be included in an amount of 0.1% to 10.0% by weight relative to the total weight of the anode composite layer. Preferably, it may be included in an amount of 0.2% or more, 0.3% or more, 0.5% or more, or 0.7% or more by weight, and may also be included in an amount of 8.0% or less, 6.0% or less, or 5.0% or less by weight. Although a higher amount of the conductive material may be advantageous for forming a conductive path, the capacity may be reduced due to a relative decrease in the amount of active material, and controlling the amount of input is not easy due to dispersion issues; however, since the effect of forming a conductive path can be maximized by optimizing dispersibility within the above range, it may be desirable to apply the conductive material within the aforementioned range.

[0130] The above binder serves to improve the adhesion between positive active material particles and the adhesion between the positive active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, polyacrylic acid, and polymers in which hydrogens thereof are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these alone or a mixture of two or more may be used.

[0131] The above binder may be included in an amount of 0.1% to 10.0% by weight relative to the total weight of the anode composite layer. Preferably, it may be included in an amount of 0.2% or more, 0.3% or more, 0.5% or more, or 0.7% or more by weight, and may also be included in an amount of 8.0% or less, 6.0% or less by weight, or 5.0% or less by weight.

[0133] 3) Method for manufacturing electrodes

[0134] An electrode according to the third aspect may be manufactured by the following manufacturing method. The manufacturing method comprises: a step (S1a) of applying an electrode slurry containing an electrode active material to a portion of a current collector; a step (S1b) of applying an insulating composition to a current collector in a portion adjacent to the area where the electrode slurry is applied but where the electrode slurry is not applied; and a step (S2) of drying the electrode slurry and the insulating composition applied to the current collector to form an electrode composite layer and an insulating layer. In this case, the insulating composition may be according to the first aspect and / or the second aspect.

[0135] The above step S1a can be manufactured according to a conventional electrode manufacturing method. Specifically, it can be manufactured by dissolving or dispersing an electrode active material, a binder, and a conductive material in a solvent to produce an electrode slurry, applying it onto an electrode current collector, and then drying and rolling.

[0136] The above step S1b can also be manufactured according to a conventional method for manufacturing an insulating layer. For example, the insulating composition can be manufactured by mixing inorganic particles and a binder in a solvent and performing a dispersion process. Specifically, each component of the composition is mixed by placing the particles in a solvent and mixing them. At this time, the mixing can be performed using mixing devices well known in the art, such as a homo mixer, but is not limited thereto.

[0137] The composition obtained from the above mixing process is milled to disperse it. The milling can be performed using a ball mill, a bead mill, or a basket mill, and more specifically, using a bead mill. Meanwhile, the degree of dispersion of the composition can be controlled by adjusting milling conditions such as the number of times the composition is passed through the ball mill, bead mill, or basket mill (hereinafter referred to as "Pass count") and rotor speed.

[0138] Steps S1a and S1b above can be performed simultaneously or sequentially before the drying process of step S2 is performed. Specifically, a coater having multiple nozzles can be used to simultaneously apply an electrode slurry and an insulating composition onto a current collector, and the process can be designed so that the electrode slurry coating equipment and the insulating composition coating equipment are sequentially arranged in the direction of travel of the conveyor so that all coatings can be performed before drying.

[0139] The above S2 step may be a drying process, and conditions generally applied in this technical field may be applied, for example, at 50°C to 300°C, preferably at 60°C or higher, or at 70°C or higher, and drying may also be performed at a temperature of 250°C or lower, 200°C or lower, or 150°C or lower.

[0140] The electrode slurry may have a solid content of 40% to 80% by weight, and the content may be appropriately controlled depending on whether the electrode slurry is an anode slurry or a cathode slurry, and preferably may be appropriately controlled within a range of 45% to 75% by weight. When the solid content is controlled within the above range, mixing of the electrode slurry and the insulating composition may not occur, and the problem of the insulating composition penetrating into the interface between the electrode composite layer and the current collector may not occur.

[0142] 4. Electrode according to the fourth aspect

[0143] According to a fourth aspect, the apparatus comprises: a current collector; an electrode composite layer provided on a portion of the current collector and comprising an electrode active material; and an insulating layer disposed on the current collector adjacent to the electrode composite layer but not on the electrode composite layer, wherein the electrode composite layer has a loading amount of 400 mg / 25 cm 2 The above is an example, and the insulating layer is provided with an electrode having a maximum width of 2.0 mm or less.

[0144] The above electrode has the advantage of being able to increase the loading amount despite the narrow width of the insulating layer, thereby enabling the expectation of high capacity and high energy density. This may be achieved by the insulating layer being derived from the insulating composition according to the first and / or second aspects, and the insulating layer may be substantially identical to the solid component of the insulating composition and the content of the component.

[0145] When forming an insulating layer using an insulating composition according to the first aspect and / or the second aspect, the width of the insulating layer may be up to 2.0 mm or less, and preferably, 1.9 mm or less, 1.8 mm or less, 1.7 mm or less, 1.6 mm or less, or 1.5 mm or less.

[0146] In this way, it is possible to form a narrow width and at the same time form a thick wet thickness, so that the insulating layer can be formed uniformly and thickly. Therefore, since such an insulating layer can be formed, it can perform the function of a dam for the electrode slurry, and thereby has the advantage of minimizing the sliding portion.

[0147] If the sliding portion is excessively formed, the capacity ratio (N / P ratio) between the anode and cathode may be reversed. This can lead to the cathode being unable to accept lithium ions transferred from the anode, causing lithium precipitation. If this precipitation persists, it can result in a short circuit, posing a risk of fire.

[0148] However, the electrode according to the fourth aspect above can prevent the above-mentioned problem because the sliding portion can be minimized through the insulating layer. In addition, since the formation of such a sliding portion can be minimized even if the loading amount of the electrode composite layer is increased to make it slightly thicker, high capacitance can be achieved, and the narrow width of the insulating layer prevents interference during electrode tab welding, thereby significantly reducing the possibility of wire breakage. This is because the loading amount is 400 mg / 25 cm 2 This can be said to be an effect resulting from the fact that it is possible to implement an electrode with a maximum insulating layer width of 2.0 mm or less.

[0149] In addition to the problem that the capacity may decrease when the maximum value of the insulating layer width is greater than 2.0 mm, when manufacturing a stack cell by stacking unit cells, welding is performed between electrode tabs. In this process, electrode tabs arranged at various heights are gathered in one place and welded, and if the width of the insulating layer is wide, the electrode tabs may fold and cause a breakage. That is, the electrode according to the fourth aspect has a loading amount greater than a specific value and the maximum value of the insulating layer width is 2.0 mm or less, which means that it can have the effect of preventing the problem of electrode tab breakage along with high loading and high energy density characteristics.

[0150] In addition, the insulating layer may have an average thickness (Dave) of 10 μm to 100 μm. Preferably, it may be 15 μm or more, 20 μm or more, 25 μm or more, or 30 μm or more, and may also be 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, or 50 μm or less.

[0151] The types, characteristics, and content of the materials constituting the insulating layer, such as inorganic particles, polymer materials, and clay, may be substantially the same as those described in the insulating composition according to the first and / or second aspects, and the technical characteristics of the electrode composite layer constituting the electrode, such as the components, types, and content thereof, current collectors, cases of positive and negative electrodes, etc., may be substantially the same as those described in the electrode according to the third aspect. Therefore, a specific description thereof is omitted, and for matters not specifically described, the description of the electrode according to the third aspect may be applied as is.

[0153] 5. Secondary battery according to the fifth aspect

[0154] A secondary battery according to the fifth aspect may be characterized by comprising an electrode assembly in which a plurality of electrodes and a separator are alternately stacked, wherein at least one of the electrodes is an electrode according to the third aspect and / or the fourth aspect.

[0155] Since the above electrode is the same as previously described, a detailed explanation is omitted, and only the remaining components are described in detail below.

[0156] The above secondary battery may be a lithium secondary battery or a sodium secondary battery, and may be an all-solid-state secondary battery or a non-aqueous electrolyte secondary battery. If the above secondary battery is a non-aqueous electrolyte secondary battery, the above secondary battery may optionally further include a battery container housing an electrode assembly which is a collection of unit cells including the positive electrode, the negative electrode, and the separator, and a sealing member for sealing the battery container. Additionally, if the above secondary battery is an all-solid-state secondary battery, a solid electrolyte membrane may be applied instead of the separator.

[0158] In the above secondary battery, the separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. Any separator typically used in secondary batteries may be used without special limitations, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte moisture retention capacity. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may be used. Furthermore, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0159] Examples of electrolytes used in the above secondary battery include organic liquid electrolytes or inorganic liquid electrolytes that can be used in the manufacture of secondary batteries, but are not limited to these.

[0160] The above electrolyte may include an organic solvent and a lithium salt. The above organic solvent may be used without special limitations as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene and fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.

[0161] The above lithium salt may be used without special restrictions as long as it is a compound capable of providing lithium ions used in secondary batteries. Specifically, as the anion of the above lithium salt, F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - The lithium salt may be at least one selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. It is preferable to use the lithium salt within the range of 0.1 to 2.0 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and lithium ions can move effectively.

[0162] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the above additives may be included in an amount of 0.1 to 5 weight% based on the total weight of the electrolyte.

[0163] If the above secondary battery is an all-solid-state secondary battery, the applicable solid electrolyte may be selected from solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes, and the above inorganic electrolyte may be a sulfide-based solid electrolyte or an oxide-based solid electrolyte. The specific type of compound may be appropriately applied as known in the industry.

[0165] Since the above secondary battery stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it can be useful in portable devices such as mobile phones, laptop computers, and digital cameras, as well as in electric vehicle fields such as hybrid electric vehicles (HEVs).

[0166] In another aspect, a battery box comprising the secondary battery as a unit cell may be provided. The battery box may include a plurality of battery cells that are unit cells and may include a packaging that accommodates the plurality of battery cells. Here, the battery box may be, for example, a battery module or a battery pack.

[0167] In addition, in another aspect, an electric device including the battery box may be provided. The battery box may be used as a power source for the electric device. The electric device may be, for example, a power tool; an electric vehicle including an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or one or more large devices among a power storage system.

[0169] Examples

[0170] The present invention will be explained in more detail below through examples. However, the following examples are intended to illustrate the present invention and do not limit the scope of the present invention.

[0172] Examples 1 to 6 and Comparative Examples 1 to 3

[0173] Carboxymethyl cellulose (CMC) and clay as functional group-containing polymers in water, an aqueous solvent, with an average particle size (D 50 ) 25 nm hectorite (laponite, BYK) was added and mixed in a homo mixer (Dispermat LC, VMA) at 2,500 rpm for 5 minutes, then D 50 It is 1.0 μm, with a specific surface area of ​​approximately 5.0 m² 2 / g to 8.5 m 2 Boehmite (product name: BP10, manufacturer: KEATON), styrene-butadiene copolymer (SBR), and activated carbon were added to the mixture and mixed at 2,500 rpm for 25 minutes.

[0174] Next, an insulating coating composition was prepared by performing a dispersion process using a bead mill (product name: LS-1, manufacturer: Netzsch) with a rotor speed of 3300 RPM, a 1-pass discharge rate of 540 g / min, and 8 passes.

[0175] The content of the components applied in each example and comparative example (parts by weight based on 100 parts by weight of solid content) is as described in Table 1 below, and the SBR and activated carbon were added in amounts of 8 parts by weight and 0.2 parts by weight, respectively, and the amount of water, an aqueous solvent, was adjusted so that the solid content is as described in Table 1 below.

[0176] inorganic particles Functional group-containing polymer (CMC) Clay Solids (weight%) Example 1 87.7 4.0 0.1 23 Example 2 87.4 4.0 0.4 17 Example 3 86.1 4.6 1.1 14 Example 4 86.8 4.0 1.0 11 Example 5 82.8 4.0 5.0 9 Example 6 79.8 4.0 8.0 5 Comparative Example 1 88.3 3.5 0 27 Comparative Example 2 77.3 4.0 10.5 4 Comparative Example 3 90.8 0 1.0 11

[0178] Experimental Example 1: Evaluation of Insulating Composition

[0179] For the insulating compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 above, the isothermal viscosity, shear rate 251 s -1 and 0.0251 s -1 The viscosity and surface tension at were measured by the following method and are shown in Table 2 below.

[0180] 1) Constant temperature viscosity (cP) : When the viscosity was 10,000 cP or less, 4.2 ml of each composition was used as a sample to measure the isothermal viscosity at room temperature (about 25°C) using an SC4-8RP chamber with an SC4-16 spindle at 12 rpm and 3 minutes, and when the viscosity was 8,000 cP to 30,000 cP, 16.1 ml of each composition was used as a sample to measure the isothermal viscosity using an SC4-13RP chamber with an SC4-25 spindle at 16 rpm and 3 minutes.

[0181] 2) Viscosity (mPa·s) by shear rate Each of the above compositions was introduced as a sample into a rheometer (HR-20 Rheometer, TA) equipped with a Cup&Bob accessory, and viscosity data were obtained at different shear rates at room temperature (approx. 23℃) (1 st (Utilizing descending values), among these, a shear rate of 251 s -1 and 0.0251 s -1 The viscosity values ​​at are shown in Table 2 below.

[0182] 3) Surface tension (mN / m) : Measurements were taken using the DCA-200 (Dynamic Contract Angle System, SEO) as the measuring equipment under the conditions of Motor speed: 15 / Probe type: Ring / Immersion Depth: 4 / Surface Detact Weight: 0.005 / Stabilization Time: 5.

[0183] Constant temperature viscosity 0.0251 s -1 viscosity 251 s -1 viscosity surface tension Example 1 5,180 8,870 370 77.2 Example 2 4,730 15,600 260 79.2 Example 3 6,800 33,420 240 82.9 Example 4 2,280 5,250 120 75.4 Example 5 4,460 109,400 150 84.1 Example 6 3,530 171,910 110 86.3 Comparative Example 1 3,400 3,200 410 72.1 Comparative Example 2 4,700 226,000 140 86.2 Comparative Example 3 1,240 2,310 110 71.1

[0184] Referring to Table 2 above, it can be seen that in the case of Comparative Example 1, which has a solid content of 27 wt%, despite the high solid content, the viscosity is low even at low shear rates because it does not contain clay, while the viscosity is measured to be relatively high at high shear rates. Additionally, it can be seen that Comparative Example 2, which contains an excessive amount of clay, exhibits a problem where the viscosity rises sharply at low shear rates, and it can be indirectly confirmed that Comparative Example 3, which does not contain a functional group-containing polymer, has low viscosity at low shear rates, making it difficult to achieve a narrow insulation width.

[0185] However, in the case of Examples 1 to 6, clay was added, and despite the extremely low solid content, the viscosity at low shear rates is significantly increased due to the relative increase in CMC within the solid content and the effect of adding clay, so it can be expected that it will be easy to achieve a thick wet thickness of the insulating layer, and at high shear rates, the viscosity actually decreases, so it can be inferred that the processability is also excellent.

[0187] Experimental Example 2: Evaluation of the width of the insulation layer

[0188] Using the insulating compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 3 above, simultaneous coating was performed on a copper current collector together with a cathode slurry in a slot die using equipment equipped with multiple coating nozzles, thereby manufacturing an electrode. At this time, the loading amount of the cathode composite layer was 400 mg / 25 cm 2 The average thickness was set to approximately 180 μm, and the thickness of the insulating layer was set to a wet thickness of 150 μm and a dry thickness of 15 μm to measure the maximum value of the insulating layer width.

[0189] Insulation layer width (mm) Example 1 1.5 Example 2 1.3 Example 3 1.3 Example 4 2.0 Example 5 1.2 Example 6 1.2 Comparative Example 1 2.5 Comparative Example 2 - Comparative Example 3 2.5

[0190] Referring to Table 3 above, it can be seen that the insulation width of Examples 1 to 6 is formed to be smaller than 2.0 mm, whereas Comparative Examples 1 and 3 are formed to be wider than 2.0 mm, as expected from the results of Table 1 above, and thus it can be seen that high loading and high energy density electrodes could not be implemented indirectly. In the case of Comparative Example 2, although mixing inside the equipment was easy due to the low high shear viscosity, there is a part where the shear force is low when the insulating liquid is discharged to the outside through the die inside the equipment, and the viscosity rises rapidly in this part, causing the discharge port to become clogged, so the insulating coating could not be performed.

[0191] In other words, it can be confirmed from the above results that by controlling the clay content while including a polymer containing functional groups, the viscosity of the insulating composition can be effectively controlled according to the shear rate, and thereby a narrow insulation width can be achieved.

Claims

Claim 1 An insulating composition comprising 35% by weight or less of solid content based on the total weight, wherein the solid content comprises inorganic particles, a polymer material, and clay, wherein the clay has positive and negative charges distributed within the particles and is included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of solid content, and wherein the polymer material comprises a functional group-containing polymer. Claim 2 An electrode insulating composition according to claim 1, wherein the solid content is included in an amount of 27 weight% or less with respect to the total weight of the insulating composition. Claim 3 An electrode insulating composition according to claim 1, wherein the clay is included in an amount of 0.05 to 5 parts by weight per 100 parts by weight of solid content. Claim 4 An electrode insulating composition according to claim 1, wherein the inorganic particles are included in an amount of 60 to 92 parts by weight per 100 parts by weight of solid content, and the polymer material is included in an amount of 5 to 20 parts by weight per 100 parts by weight of solid content. Claim 5 An electrode insulating composition according to claim 1, wherein the inorganic particles comprise one or more selected from the group consisting of boehmite (AlOOH), aluminum hydroxide (Al(OH)3), magnesium hydroxide (Mg(OH)2), alumina (Al2O3) and zirconia (ZrO2). Claim 6 An electrode insulating composition according to claim 1, wherein the functional group-containing polymer comprises one or more functional groups selected from the group consisting of carboxyl groups, ester groups, amide groups, and cyano groups. Claim 7 An electrode insulating composition according to claim 1, wherein the polymer material further comprises a binder, and the binder comprises one or more selected from the group consisting of styrene-butadiene copolymer, acrylate styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, and polyvinyl alcohol. Claim 8 An electrode insulating composition according to claim 1, wherein the clay is a plate-shaped particle comprising one or more selected from the group consisting of hectorite, saponite, and bentonite. Claim 9 The electrode insulating composition according to claim 1, wherein the insulating composition further comprises an aqueous solvent. Claim 10 An electrode insulating composition according to claim 1, wherein the insulating composition further comprises a hydrophobic additive, and the hydrophobic additive comprises activated carbon. Claim 11 An electrode comprising: a current collector; an electrode composite layer provided on a part of the current collector and comprising an electrode active material; and an insulating layer disposed on a current collector adjacent to the electrode composite layer but not provided with the electrode composite layer, wherein the insulating layer comprises inorganic particles, a polymer material, and clay, wherein the clay has positive and negative charges distributed within the particles and is included in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the insulating layer, and the polymer material comprises a functional group-containing polymer. Claim 12 In claim 11, the electrode active material is a negative electrode active material, and the negative electrode active material comprises one or more selected from the group consisting of silicon-based active materials, carbon-based active materials, and silicon-carbon composite active materials. Claim 13 In claim 11, the electrode, wherein the electrode composite layer further comprises a binder and a conductive material. Claim 14 A secondary battery comprising the electrode described in paragraph 11.

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