Acrylic elastomer particles as additive for electrode mixture and dry electrode manufactured comprising same

Abstract

Acrylic elastomer particles according to one aspect of the present disclosure can enhance binder properties of fluorine-based resin particles, leading to the production of an electrode mixture having stronger binder properties to an electrode active material. A dry electrode manufactured comprising same is not easily broken due to excellent mechanical properties thereof, leading to the provision of a secondary battery with superb stability, excellent battery performance, and long-term maintenance of excellent battery performance.

Description

Acrylic elastomer particles as an additive in electrode mixture and a dry electrode manufactured including the same

[0001] The present disclosure provides acrylic elastomer particles as an additive for improving the mechanical strength and formability of a dry electrode.

[0002] Currently, the energy industry is facing global issues such as cost instability due to the depletion of fossil fuels and environmental pollution caused by the use of fossil fuels. As a result, carbon emission regulations have been strengthened, and the demand for secondary batteries has been rapidly increasing.

[0003] The main components of the above secondary battery are a cathode, an electrode, and an electrolyte. Currently, the demand for all-solid-state secondary batteries, in which the electrolyte is replaced with a solid electrolyte, is increasing. The all-solid-state secondary batteries have superior stability compared to secondary batteries using liquid electrolytes, and thus the demand is increasing.

[0004] In particular, among the main components of secondary batteries, electrodes are typically manufactured using a wet process. The wet process involves dispersing electrode active materials and conductive materials in a solution containing a dissolved binder to produce a dispersion solution for electrode manufacturing, and then coating and drying the produced dispersion solution on an electrode current collector to form an electrode.

[0005] The above conventional electrode manufacturing method using a wet process has the advantage of being able to manufacture an electrode in which an electrode active material layer is formed in which the electrode active material is evenly dispersed on a current collector, but it inevitably has many disadvantages in that it uses a solvent.

[0006] For example, since the conventional wet process must include a process of drying the solvent included in the dispersion solution for electrode manufacturing, the process is complex and the volume of the process equipment inevitably increases.

[0007] Furthermore, solvents such as n-methylpyrrolidone used in the wet electrode process are expensive, making them uneconomical. Furthermore, recovering these expensive solvents necessitates the addition of a bulky solvent recycling process device. Therefore, the conventional wet process faces several technical limitations in improving the process's economic feasibility.

[0008] The above wet process not only has the conventional process complexity and economic problems described above, but can also have a negative impact on the performance of secondary batteries manufactured by the wet process.

[0009] For example, the conventional wet process described above has a problem in that if the solvent is not completely dried, the performance and stability of the secondary battery are significantly reduced, so in order to solve the complex process of the wet process described above, the solvent drying time cannot be hastily shortened, and thus energy consumption increases significantly in order to completely dry the solvent.

[0010] As a process to solve the above problems, an electrode active layer composition is manufactured by kneading an electrode active material, a conductive material, and a binder without using a solvent, and then the manufactured electrode composition is manufactured into a film through a dry process or laminated with a current collector for use.

[0011] Since the above conventional dry process does not use any solvent at all, it has high economic efficiency compared to the wet process described above, has the advantage of reducing the volume of process equipment, and can solve the problem of secondary battery performance deterioration due to undried solvent.

[0012] However, the conventional dry process electrode manufacturing method has a very difficult time evenly dispersing the electrode active material compared to the electrode manufactured by the wet process described above.

[0013] In addition, the electrode mixture of the dry process is preferably composed of a large amount of binder for adhesion to the current collector and high mechanical strength, but it faces a complementary relationship in physical properties that prevents the electrode from containing a large amount of binder in order for the manufactured electrode to have excellent conductivity.

[0014] That is, since the conventional dry process cannot include an excessive amount of binder in terms of manufacturing a dry electrode having sufficient electrical conductivity, there is a problem that particles of the electrode active material, and further particles of the electrode active material and conductive material, collide with each other during the process of stirring the electrode active material and binder. Since the conventional dry process stirs while the particles collide, it may place excessive load on the machine, generate noise due to collisions between particles, and cause damage to the particles, which may lower the performance of the manufactured dry electrode.

[0015] Therefore, for the reasons explained above, conventional dry processes not only have poor mixing process (kneading process for electrode mixtures), but also produce poor mechanical properties of the resulting dry electrodes. Consequently, dry electrodes manufactured using conventional dry processes are prone to fracture (cracking) due to their low mechanical properties and external stress, resulting in inadequate secondary battery performance.

[0016] Therefore, in order to solve the problems of the dry electrode manufactured by the conventional dry process, a new technology is needed that has excellent binder properties for the electrode active material and improves the mechanical properties of the dry electrode manufactured including the same, thereby solving the problem of performance degradation of the secondary battery due to breakage of the dry electrode.

[0017] According to one aspect of the present disclosure, there is provided an acrylic elastomer particle that can have further improved binder properties for an electrode active material due to excellent complementary effects with fluorine-based resin particles.

[0018] According to one aspect of the present disclosure, an electrode mixture capable of manufacturing an electrode having excellent mechanical strength even when manufactured by a dry process is provided.

[0019] According to one aspect of the present disclosure, an electrode mixture having excellent processability is provided without limitation on the molding process method for manufacturing a dry electrode.

[0020] According to one aspect of the present disclosure, a dry electrode is provided with excellent processability that minimizes the load on equipment by using the electrode mixture.

[0021] The present disclosure provides acrylic elastomer particles included as a binder additive in an electrode composite.

[0022] As one aspect of the present disclosure, the acrylic elastomer particles are C1-C 12 It is manufactured by including an alkyl-substituted (meth)acrylate and a crosslinking agent containing two or more unsaturated groups, and the degree of crosslinking calculated by the following formula 1 may be 50% or more.

[0023] [Formula 1]

[0024]

[0025] (In the above equation 1, W0 is the dry mass of the initial acrylic elastic particles, and W1 is the dry mass of the acrylic elastic particles heated in dichloromethane at a temperature of 100 ℃ for 3 hours.)

[0026] As one aspect of the present disclosure, the acrylic elastic particles may have a glass transition temperature of -40 to 0°C as measured under a temperature increase condition of 10°C per minute using DSC (Differential Scanning Calorimetry).

[0027] In another aspect of the present disclosure, the acrylic elastomer particles may have a glass transition temperature of -40 to -20°C.

[0028] As one aspect of the present disclosure, the C1-C 12The alkyl-substituted (meth)acrylate may include n-butylacrylate.

[0029] In one embodiment of the present disclosure, the crosslinking monomer may be one or two or more selected from 2,2-ethanediol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, divinylbenzene, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, and allyl(meth)acrylate.

[0030] As one aspect of the present disclosure, the acrylic elastomer particles may have a crosslinking degree of 70 to 90%.

[0031] As one aspect of the present disclosure, the acrylic elastomer particles may have a core-shell form further including a continuous non-crosslinked acrylic resin shell layer on the surface.

[0032] As one aspect of the present disclosure, the core-shell type acrylic elastomer particles may have an acrylic resin shell layer having a mass of 50 wt% or less with respect to the total mass.

[0033] As one aspect of the present disclosure, the acrylic resin shell layer may be a methyl methacrylate homopolymer or a methyl methacrylate copolymer.

[0034] As one aspect of the present disclosure, the acrylic elastomer particles are C2-C containing a hydroxyl group. 12 It may be manufactured by further including an alkyl-substituted (meth)acrylic monomer.

[0035] As one aspect of the present disclosure, the acrylic elastomer particles contain C2-C containing a hydroxyl group based on the total amount of monomers input during manufacturing. 12 It may further contain up to 30 wt% of an alkyl-substituted (meth)acrylic monomer.

[0036] As one aspect of the present disclosure, the acrylic elastomer particles may be manufactured by further including an α-olefin monomer.

[0037] As one aspect of the present disclosure, the acrylic elastomer particles may have an average particle diameter (D50) of 0.01 to 50 μm.

[0038] The present disclosure can provide an electrode mixture comprising the acrylic elastomer particles, fluorine-based resin particles, and an electrode active material.

[0039] In one embodiment of the present disclosure, the electrode active material may be a particle of a lithium composite metal oxide including lithium metal and one or more selected from nickel, cobalt, manganese, sodium, magnesium, calcium, titanium, vanadium, chromium, copper, zinc, germanium, strontium, silver, zirconium, niobium, tungsten, gallium, molybdenum, aluminum, tantalum, and boron.

[0040] As one aspect of the present disclosure, the fluorine-based resin particles may be polymerized by including one or more fluorine-based monomers selected from vinylidene difluoride, vinyl fluoride, chlorotrifluoroethylene, tetrafluoroethylene, perfluoroalkyl vinyl ether, and hexafluoropropylene.

[0041] As one aspect of the present disclosure, the fluorine-based resin particles may have an average particle diameter (D50) of 0.01 to 50 μm.

[0042] As one aspect of the present disclosure, the electrode mixture may contain 0.1 to 30 parts by weight of fluorine-based resin particles with respect to 100 parts by weight of electrode active material.

[0043] As one aspect of the present disclosure, the electrode mixture may contain 0.01 to 10 parts by weight of acrylic elastic particles with respect to 100 parts by weight of electrode active material.

[0044] As one aspect of the present disclosure, the electrode mixture may further include 5 parts by weight or less of a conductive material per 100 parts by weight of an electrode active material.

[0045] As one embodiment of the present disclosure, when the electrode mixture comprises 4 to 6 parts by weight of fluorine-based resin particles and 0.5 to 1.5 parts by weight of acrylic elastomer particles for 100 parts by weight of electrode active material, the energy for processing at 150°C and 15 rpm at a fill factor of 90% of a batch mixer may be 120 Nm or less.

[0046] The present disclosure can provide a dry electrode manufactured by including the above electrode mixture.

[0047] As one aspect of the present disclosure, when the dry electrode comprises 4 to 6 parts by weight of fluorine-based resin particles and 0.5 to 1.5 parts by weight of acrylic elastomer particles with respect to 100 parts by weight of electrode active material, the dry electrode may have the following mechanical properties measured by ISO 527-2.

[0048] (1) Tensile strength at break of 2.5 MPa or more

[0049] (2) Breaking elongation of 10% or more

[0050] (3) Modulus of 50 to 100 MPa

[0051] As one aspect of the present disclosure, the electrode mixture includes an acrylic elastomer and has excellent binder properties for an electrode active material due to excellent mutual complementarity with a fluorine resin, so that a dry electrode capable of preventing deterioration of physical properties due to detachment of the electrode active material can be manufactured.

[0052] As one aspect of the present disclosure, since the electrode mixture has excellent processability or applicability, it is possible to manufacture a dry electrode of a certain shape (excluding an electrode current collector) or a dry electrode evenly applied to an electrode current collector, and thus a secondary battery having excellent performance and being able to maintain excellent performance for a long period of time can be manufactured.

[0053] As one aspect of the present disclosure, the dry electrode is manufactured from an electrode mixture that does not contain a solvent, and therefore can be manufactured with better economic efficiency and processability than a conventional wet process electrode manufacturing method.

[0054] As one aspect of the present disclosure, a dry electrode manufactured including the electrode mixture has a tensile strength at break of 2.5 MPa or more, an elongation at break of 10% or more, and a modulus of 50 to 100 MPa as measured by ISO 527-2, and thus is not easily broken or deformed by external force, has excellent battery performance, and can provide a secondary battery that can maintain battery performance for a long period of time.

[0055] As one aspect of the present disclosure, since the energy for manufacturing a dry electrode at a rotational speed of 10 rpm using the electrode mixture has excellent processability of 120 Nm or less, the load on equipment in manufacturing a dry electrode can be prevented, and the deterioration of the physical properties of the dry electrode due to friction between particles of electrode active material and conductive material included in the electrode mixture can be prevented.

[0056] Figure 1 is a scanning electron microscope photograph of acrylic elastomer particles manufactured in Example 1.

[0057] Figure 2 is a film manufactured from the electrode mixture manufactured in Example 8.

[0058] Figure 3 is a scanning electron microscope photograph of the electrode mixture manufactured in Example 8.

[0059] Figure 4 is a scanning electron microscope photograph of the electrode mixture manufactured in Comparative Example 2.

[0060] Hereinafter, the acrylic elastic particles, electrode mixture, dry electrodes and secondary batteries manufactured therefrom will be described.

[0061] Unless otherwise defined, the technical and scientific terms used herein have the meaning commonly understood by a person of ordinary skill in the technical field to which this invention pertains, and in the following description, descriptions of well-known functions and configurations that may unnecessarily obscure the gist of the present invention are omitted.

[0062] Additionally, the singular forms used in this disclosure may be intended to include the plural forms as well, unless the context specifically indicates otherwise.

[0063] In addition, units used in the present disclosure without special mention are based on weight, and for example, units of % or ratio mean weight% or weight ratio, and weight% means the weight% that any one component of the entire composition occupies in the composition unless otherwise defined.

[0064] Additionally, the numerical ranges used in the present disclosure include lower and upper limits and all values ​​within the range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specifically defined in the specification of the present invention, values ​​outside the numerical range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0065] The term "includes" in this disclosure is an open-ended description having an equivalent meaning to expressions such as "comprises," "contains," "has," or "characterizes," and does not exclude additional elements, materials, or processes not listed.

[0066] The term “(meth)acrylate” in the present disclosure may mean methacrylate or acrylate.

[0067] The conventional method of manufacturing an electrode by coating an electrode active material on an electrode current collector used a wet process in which an electrode active material and a conductive material were dispersed in a solution in which a binder resin was dissolved, the solution was coated on a current collector, and then dried.

[0068] However, the above conventional wet process has a problem in that it must include a process for drying the solvent, and if the solvent is not completely dried in the solvent drying process, the performance of the electrode deteriorates.

[0069] In order to solve the problems of the electrode manufacturing method using the above conventional wet process, the electrode manufacturing method uses a dry process in which a binder, an electrode active material, and a conductive material are mixed to manufacture an electrode mixture, the manufactured electrode mixture is molded to manufacture an electrode active material film, or a film molded with the electrode mixture is laminated on an electrode current collector to manufacture a dry electrode.

[0070] The electrode manufacturing method using the above conventional dry process has the advantage of excellent processability and economic feasibility compared to the electrode manufacturing method using the wet process, and also prevents deterioration of the electrode properties due to the non-dried solvent.

[0071] However, the electrode manufacturing method using the conventional dry process has problems in that it is still difficult to apply a binder with excellent adhesiveness to prevent the detachment of the electrode active material, and in particular, the active material layer of the manufactured dry electrode has low mechanical properties that easily break under external force, resulting in low performance of the manufactured secondary battery and inability to guarantee stability.

[0072] Accordingly, the present disclosure provides a binder additive having better adhesive properties than conventional binders, and provides a dry electrode having an active material layer having excellent mechanical properties that are not easily broken by external force.

[0073] In the present specification, the dry electrode may include a film layer of only an electrode active material layer or a form in which a current collector and the film layer are laminated.

[0074] In the case of a dry electrode composed only of the above active material layer, a cell can be manufactured by stacking a negative dry electrode and a positive dry electrode on both sides of a solid electrolyte, and a battery can also be manufactured in which the dry electrode, solid electrolyte, and counter dry electrode are stacked in multiple orders.

[0075] In the above-mentioned type of battery, the dry electrode may be manufactured only with an active material layer film as described above, or may be a positive electrode dry electrode or a negative electrode dry electrode in which the film is integrated on both sides of a current collector.

[0076] The present disclosure can provide acrylic elastomer particles included as a binder additive in an electrode composite.

[0077] The above-described acrylic elastic particles have excellent complementarity with the fluorine-based resin particles, so that not only can the binder properties of the fluorine-based resin particles be further improved, but also the dry electrode manufactured from the electrode mixture described above can have excellent mechanical strength that is not easily broken by external force.

[0078] As one aspect of the present disclosure, the acrylic elastomer particles are C1-C 12 It may be manufactured by including an alkyl-substituted (meth)acrylate and a crosslinking agent containing two or more unsaturated groups, and the degree of crosslinking calculated by the following formula 1 may be 50% or more.

[0079] [Formula 1]

[0080]

[0081] (In the above equation 1, W0 is the dry mass of the initial acrylic elastic particles, and W1 is the dry mass of the acrylic elastic particles heated in dichloromethane at a temperature of 100 ℃ for 3 hours.)

[0082] Since the above-described acrylic elastic particles have a cross-linking degree of at least 50%, the electrode mixture including the above-described acrylic elastic particles does not cause the electrode active material to detach, and by manufacturing the electrode mixture described above using a dry process, the mechanical properties of the manufactured dry electrode are improved, and a dry electrode having an electrode active material layer that is not easily broken by external force can be manufactured.

[0083] In another aspect of the present disclosure, the acrylic elastomer particles may have a crosslinking degree of 60% or more, preferably 70% or more, more preferably 80% or more, and although not limited to an upper limit, may be 99% or less, 98% or less, 97% or less, or 95% or less, preferably 70 to 90%.

[0084] Acrylic elastomer particles having a crosslinking degree in the above range have excellent compatibility with fluorine-based resin particles, and an electrode mixture manufactured including the same can further enhance the binder properties of an electrode active material by combining the acrylic elastomer particles with the fiberization of the fluorine-based resin particles that occurs during the manufacturing process. In addition, an electrode mixture including acrylic elastomer particles having a crosslinking degree in the above range can further improve moldability and electrical properties, and thus a dry electrode with excellent electrical performance can be manufactured by including the binder mixture described above.

[0085] In addition, a binder mixture including acrylic elastomer particles having a crosslinking degree in the above range can manufacture a dry electrode having high mechanical strength in addition to the above advantages, and thus, a dry electrode having a low defect rate and superior performance can be manufactured compared to a dry electrode manufactured including a conventional electrode mixture.

[0086] In one embodiment of the present disclosure, the acrylic elastomer particles may have a glass transition temperature of -40 to 0°C, and in another embodiment, -40 to -5°C, -40 to -10°C, -40 to -15°C, -40 to -20°C, -35 to -20°C, or -30 to -20°C.

[0087] Acrylic elastomer particles having a glass transition temperature in the above range can be used to manufacture an electrode mixture with excellent mixing properties with a fluorine-containing carrier and an electrode active material even when stirred at a low temperature, and a dry electrode manufactured including the manufactured electrode mixture can have high mechanical properties, so it may be preferred, but this is not necessarily a limitation.

[0088] The glass transition temperature of the above acrylic elastic particles may be measured using DSC (Differential Scanning Calorimetry) under a temperature increase condition of 10°C per minute, and a more detailed measurement method is described in the examples below, so a detailed description thereof will be omitted.

[0089] As one aspect of the present disclosure, the C1-C 12 The alkyl-substituted (meth)acrylate may include one or more selected from methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and butyl (meth)acrylate.

[0090] The above acrylic elastic particles are not particularly limited as long as they do not impair physical properties, but in terms of excellent complementarity with fluorine-based resin particles and excellent mechanical properties of a dry electrode manufactured including the same, it may be preferred to manufacture the particles including the C1-C4 alkyl-substituted (meth)acrylate described above.

[0091] In another aspect of the present disclosure, the C1-C 12 The alkyl-substituted (meth)acrylate may include n-butylacrylate.

[0092] The acrylic elastomer particles manufactured including the above n-butyl acrylate have a glass transition temperature (Tg) of -30 to -10°C, so that an electrode mixture in which the acrylic elastomer particles are evenly dispersed can be manufactured even when stirred at a low temperature, and the fibers formed from the fluorine-based resin particles in the manufactured electrode mixture can be further reinforced to further improve the mechanical properties of the electrode mixture, which may be preferred, but this is not necessarily a limitation as long as it does not impair the properties of the electrode mixture.

[0093] That is, as one aspect of the present disclosure, the C1-C 12 Alkyl-substituted (meth)acrylates are C1-C acrylates added in the production of acrylic elastomer particles, in that they further enhance the effect of acrylic elastomer particles, including n-butylacrylate, as described above. 12 With respect to the total amount of alkyl-substituted (meth)acrylate, n-butyl (meth)acrylate may be included in an amount of 80 wt% or more, 85 wt% or more, 88 wt% or more, 90 wt% or more, or 95 wt% or more, and although the upper limit is not limited, it may be included in an amount of 100 wt% or less.

[0094] As one aspect of the present disclosure, the C1-C 12 The alkyl-substituted (meth)acrylate may be included in an amount of 50 wt% or more based on the total amount of monomers (including crosslinking monomers containing two or more unsaturated groups) used in the manufacture of the acrylic elastomer particles, and in another embodiment, may be included in an amount of 60 wt% or more, 70 wt% or more, 80 wt% or more, or 90 wt% or more, and the upper limit is not limited, but may be 95 wt% or less.

[0095] C1-C with the content in the above range 12Acrylic elastomer particles manufactured including alkyl-substituted (meth)acrylates can have excellent complementarity with fluorine-based resin particles, and can be preferred because they can manufacture a binder mixture having excellent binder properties of an electrode active material, but this is not necessarily limited as long as it does not impair the physical properties of the acrylic elastomer particles.

[0096] As one aspect of the present disclosure, the acrylic elastomer particles are C2-C containing a hydroxyl group. 12 It may be manufactured by further including an alkyl-substituted (meth)acrylic monomer.

[0097] C2-C containing the above hydroxyl group 12 Acrylic elastomer particles manufactured by further including an alkyl-substituted (meth)acrylic monomer can have superior binder properties for electrode active materials due to excellent complementarity with fluorine-based resin particles.

[0098] Also, C2-C containing the above hydroxyl group 12 Acrylic elastomer particles manufactured by further including an alkyl-substituted (meth)acrylic monomer can not only further improve elasticity, but also can be preferred because the electrode mixture manufactured by including the same can be coated on the electrode current collector with better adhesiveness, but this is not necessarily a limitation.

[0099] C2-C containing the above hydroxyl group 12 The alkyl-substituted (meth)acrylic monomer is not particularly limited, but may be one or more selected from, but not limited to, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 5-hydroxypentyl (meth)acrylate.

[0100] In another embodiment, C2-C containing the hydroxyl group 12The alkyl-substituted (meth)acrylic monomer may include 2-hydroxyethyl (meth)acrylate, or 2-hydroxyethyl (meth)acrylate may be used alone.

[0101] The acrylic elastomer particles manufactured including the above 2-hydroxyethyl (meth)acrylate may be preferred because they can manufacture electrode compounds even at low temperatures, including electrode compounds and fluorine-based importers. However, this is not necessarily limited as long as it can manufacture a dry electrode satisfying the properties targeted by the present disclosure.

[0102] As one aspect of the present disclosure, C2-C containing the hydroxyl group 12 The alkyl-substituted (meth)acrylic monomer may be included in an amount of 20 wt% or less, 15 wt% or less, 13 wt% or less, 10 wt% or less, 8 wt% or less, 5 wt% or less, 3 wt% or less, or 1 wt% or less, based on the total amount of monomers used in the manufacture of the acrylic elastomer particles.

[0103] C2-C containing hydroxyl groups in the above range of contents 12 Acrylic elastic particles manufactured by including alkyl-substituted (meth)acrylic monomers may be preferred because they can produce electrode mixtures having better adhesion to the electrode current collector, but this is not necessarily a limitation as long as the physical properties of the acrylic elastic particles are not impaired.

[0104] As one embodiment of the present disclosure, the acrylic elastic particles may be manufactured by further including one or more α-olefins selected from ethylene, propylene, butylene, α-styrene, cyclohexyl thio(meth)acrylate, and benzylalkyl acrylic monomers, in addition to the monomers described above, as long as the physical properties are not impaired.

[0105] As can be appreciated by those skilled in the art, the above acrylic elastomer particles may be manufactured by further including the α-olefin in terms of adding excellent heat resistance, excellent chemical resistance, and high elongation of the manufactured dry electrode.

[0106] In one embodiment of the present disclosure, the crosslinking monomer may be one or two or more selected from 2,2-ethanediol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, divinylbenzene, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, and allyl(meth)acrylate.

[0107] The above crosslinkable monomer is not particularly limited as long as it contains two or more unsaturated groups capable of crosslinking, but a crosslinkable monomer containing two or more (meth)acrylate groups described above may be preferred.

[0108] The crosslinking monomer containing two or more (meth)acrylate groups described above can produce acrylic elastomer particles having even better mechanical properties, and can have excellent binder properties for electrode active materials, including the produced acrylic elastomer particles and fluorine-based resin particles, but is not necessarily limited thereto.

[0109] In another aspect of the present disclosure, the crosslinking monomer may include one or two or more selected from 1,3-butanediol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,5-pentanediol di(meth)acrylate, or it may be preferred to use 1,3-butanediol di(meth)acrylate alone.

[0110] The acrylic elastic particles manufactured including the above 1,3-butanediol di(meth)acrylate have a low glass transition temperature, so that even when kneaded with electrode active materials and fluorinated resin particles at low heat or room temperature as described above, an electrode mixture having excellent miscibility can be manufactured, and an electrode mixture having further improved mechanical properties can be manufactured due to excellent complementarity with the fluorinated resin particles, but this is not necessarily limited.

[0111] In one embodiment of the present disclosure, the crosslinking monomer may be included in an amount of 20 wt% or less based on the total amount of the monomer mixture introduced in the production of acrylic elastomer particles, and in another embodiment, may be included in an amount of 18 wt% or less, 15 wt% or less, 10 wt% or less, 9 wt% or less, 8 wt% or less, 6 wt% or less, 5 wt% or less, 4 wt% or less, 3 wt% or less, or 2 wt% or less, and the lower limit is not limited thereto, but may be 0.5 wt% or more, or 1 wt% or more, 2 wt% or more, or 3 wt% or more, and may be in any numerical range between the upper and lower limits thereof.

[0112] Acrylic elastomer particles manufactured by including a crosslinking monomer in the above range of content may be preferred because they can have better binder properties of electrode active materials than fluorine-based resin particles, and the manufactured electrode film can have better mechanical properties. However, this is not necessarily limited as long as it is possible to manufacture acrylic elastomer particles having the properties targeted in the present disclosure.

[0113] In one embodiment of the present disclosure, the acrylic elastomer particles may have an average particle diameter (D50) of 0.01 to 50 ㎛, and in another embodiment, 0.05 to 50 ㎛, 0.1 to 50 ㎛, 0.1 to 30 ㎛, 0.1 to 20 ㎛, 0.1 to 10 ㎛, 0.1 to 5 ㎛, 0.1 to 1 ㎛, or 0.1 to 0.5 ㎛.

[0114] Acrylic elastomer particles having an average particle diameter in the above range can have excellent miscibility with fluorine resin particles, and can be preferred for producing an electrode mixture containing acrylic elastomer particles with excellent dispersibility; however, this is not necessarily limited as long as it does not impair the physical properties of the electrode mixture.

[0115] The average particle diameter (D50) of the above acrylic elastic particles is measured using a laser diffraction particle size distribution measuring device (Malvern, MASTERSIZER 3000 hydro), and the average particle diameter and Span value (average particle distribution width) may be measured based on a wet measurement method, although the measurement method will be described in more detail in the examples below. However, if it is measured using a method recognizable to a person skilled in the art, there is no particular limitation thereon.

[0116] As one aspect of the present disclosure, the acrylic elastomer particles may have a core-shell form further including a continuous non-crosslinked resin shell layer on the surface.

[0117] The above core-shell type acrylic elastomer particles can have excellent long-term storage properties by preventing the acrylic elastomer particles having a low glass transition temperature from agglomerating with each other in advance of the process.

[0118] In addition, the core-shell type acrylic elastomer particles may be preferred because they maintain the excellent complementarity between the acrylic elastomer particles and the fluorine-based resin particles and the high mechanical strength of a dry electrode manufactured by including the acrylic elastomer particles, and can have the excellent long-term storage properties described above.

[0119] As one aspect of the present disclosure, the core-shell type acrylic elastomer particles may have a formed resin shell layer of a methyl methacrylate homopolymer or a methyl methacrylate copolymer.

[0120] In terms of the effect described above, it may be preferred to form the acrylic elastomer particles in the form of a methyl methacrylate homopolymer as an acrylic resin shell layer in the above-described core-shell type, but depending on the effect of heat resistance, weather resistance, wear resistance, solvent resistance, moisture resistance, binder properties, moldability, rigidity, extensibility, and bendability of the acrylic elastomer particles and the dry electrode manufactured including the same, a methyl methacrylate copolymer manufactured including other monomers may be used.

[0121] In one embodiment of the present disclosure, the methyl methacrylate copolymer may be a copolymer of methacrylate and one or more comonomers selected from a (meth)acrylate monomer, methyl acrylate, an olefin monomer, and a styrene monomer represented by the following chemical formula 1.

[0122] [Chemical Formula 1]

[0123]

[0124] (In the above chemical formula 1, R1 is hydrogen or methyl, R2 is hydrogen, a halogen group, an amine group, a cyano group, a substituted or unsubstituted hydrocarbyl group, or a substituted or unsubstituted heterohydrocarbyl group, and the substituents of the substituted hydrocarbyl group and the substituted heterohydrocarbyl group are each one or two or more selected from a halogen group, an amine group, a cyano group, a hydroxy group, and a carboxyl group.)

[0125] In another aspect of the present disclosure, the comonomer may be methyl methacrylate, methyl acrylate, a (meth)acrylate monomer represented by the chemical formula 1 described above, or a mixed monomer thereof, or may be a (meth)acrylate monomer represented by the chemical formula 1.

[0126] As one embodiment of the present disclosure, the (meth)acrylate monomer is a monomer having the chemical formula 1 described above, wherein R1 is hydrogen or methyl, and R2 is a straight or branched C1-C 20 Alkyl, straight or branched chain hydroxy substituted C1-C 20 It may be alkyl, and in another embodiment, R2 is straight or branched chain C1-C 12 Alkyl, straight chain C1-C 12 It can be alkyl or straight chain C1-C6 alkyl.

[0127] The core-shell type acrylic elastomer particles containing the methyl methacrylate copolymer described above as a resin shell layer may have excellent storage stability and may also have the additional effects described above, and may therefore be preferred; however, this is not necessarily limited as long as it has the properties targeted in the present disclosure.

[0128] In one embodiment of the present disclosure, the resin of the resin shell layer of the acrylic elastomer particles may have a weight average molecular weight of 10,000 to 1,000,000 g / mol, and in another embodiment, may have a weight average molecular weight of 10,000 to 500,000 g / mol, 10,000 to 100,000 g / mol, 10,000 to 50,000 g / mol, or 10,000 to 30,000 g / mol, but is not necessarily limited thereto.

[0129] The above weight average molecular weight measurement method may be performed using a gel permeation chromatography (GPC) device (Waters), dissolving the measurement resin in tetrahydrofuran (THF), and measuring under conditions of a column heater (ALLCOLHTRB) at 40°C and a mobile phase solvent flow rate of 1.0 mL / min, but is not limited thereto as long as it is a measurement method recognizable to a person skilled in the art.

[0130] In one embodiment of the present disclosure, the core-shell type acrylic elastomer particles may contain a resin shell layer in an amount of 10 wt% or less with respect to the total weight, and in another embodiment, may contain a resin shell layer in an amount of 8 wt% or less, 5 wt% or less, 2 wt% or less, or 1 wt% or less, and although the lower limit is not limited, it may be 0.1 wt% or more.

[0131] Acrylic elastomer particles in the core-shell form including a resin shell layer with a content in the above range may be preferred because they can have high mechanical strength of a dry electrode manufactured including the same and excellent long-term storage properties at the same time, but there is no particular limitation on this, as long as it does not impair the physical properties of the acrylic elastomer particles manufactured.

[0132] In another embodiment of the present disclosure, the average particle diameter (D50) of the core-shell type acrylic elastomer particles and the thickness ratio of the resin shell layer may be 1:0.001 to 1:1, and in another embodiment, it may be 1:0.01 to 1:1, 1:0.01 to 0.5, or 1:0.01 to 1:0.1.

[0133] Acrylic elastomer particles in a core-shell form that form a resin shell layer having a thickness ratio in the above range may be preferred because they can produce a dry electrode having excellent mechanical strength, but this is not necessarily limited thereto.

[0134] In the above core-shell type acrylic particles, the thickness of the resin shell layer can be obtained by measuring the average particle diameter (D50) of the core-shell type acrylic elastomer particles using the above-described average particle diameter (D50) measuring method, and the difference between the average particle diameter (D50) of the acrylic elastomer particles that do not form a resin shell layer.

[0135] Hereinafter, an electrode mixture containing the above acrylic elastic particles is described.

[0136] The present disclosure can provide an electrode mixture including acrylic elastomer particles, fluorine-based resin particles, and an electrode active material.

[0137] The above acrylic elastic particles can be included as a binder additive in an electrode mixture, so that the manufactured electrode mixture can have excellent moldability, and the mechanical properties of a dry electrode manufactured from the electrode mixture can be improved.

[0138] In one embodiment of the present disclosure, the electrode mixture may contain 0.01 to 10 parts by weight of acrylic elastomer particles based on 100 parts by weight of the electrode active material, and in another embodiment, it may contain 0.01 to 7 parts by weight, 0.01 to 5 parts by weight, 0.01 to 4 parts by weight, 0.01 to 3 parts by weight, 0.01 to 2 parts by weight, 0.05 to 2 parts by weight, or 0.1 to 2 parts by weight.

[0139] The above electrode mixture can further increase the binder property of the electrode active material by including the fluorine-based resin particles described below and the acrylic elastomer particles in the above range of contents, and further, the dry electrode manufactured by including the above electrode mixture is advantageous in that a fiberized fluorine-based resin is formed in the electrode active material layer, and the adhesion and mechanical strength can be further increased by the combination of the fiberized fluorine-based resin and the acrylic elastomer particles.

[0140] As observed in Fig. 3, the active material layer of the dry electrode of the present disclosure has an acrylic elastomer bonded to the surface of a fibrous fluorine resin binder. Although it is not clear, it appears that the adhesive strength between the electrode active materials is further increased by this form.

[0141] That is, the acrylic elastic particles maintain a particle shape, and when the fluororesin binder is kneaded to produce an active material film, it appears that fiberization progresses and these are combined with the particle-shaped elastic acrylic particles to more firmly fix the active material.

[0142] Therefore, as described above, the electrode mixture has excellent binder properties due to the complementary nature of the fluorine-based resin and the acrylic elastomer particles, and can manufacture a dry electrode with improved mechanical properties.

[0143] As one aspect of the present disclosure, the electrode active material may be a positive electrode active material or a negative electrode active material, but it may be preferred to use a positive electrode active material in terms of providing an electrode having excellent mechanical properties while having excellent binder properties of fluorine-based resin particles and acrylic-based elastomer particles.

[0144] In one embodiment of the present disclosure, the positive electrode active material may be a particle of a lithium composite metal oxide including, but not limited to, lithium metal and one or more selected from nickel, cobalt, manganese, phosphorus, sodium, magnesium, calcium, titanium, vanadium, chromium, copper, zinc, germanium, strontium, silver, zirconium, niobium, tungsten, gallium, molybdenum, aluminum, tantalum, and boron, as long as it is recognizable by a person skilled in the art.

[0145] In another aspect of the present disclosure, the lithium composite metal oxide may be represented by the following chemical formula 2, chemical formula 3, or chemical formula 4.

[0146] [Chemical Formula 2]

[0147] LiFePO4

[0148] [Chemical Formula 3]

[0149] LiM1FePO4

[0150] [Chemical Formula 4]

[0151] Li x [Ni y Co z Mn w M 2v ]O2

[0152] (In the above chemical formulas 3 and 4, M1 is one selected from Ni, Co, Mn, Cr, Zr, Nb, Cu, V, Ti, Zn, Al, Ga and Mg, and M2 is one or more selected from Ba, Ca, Zr, Ti, Mg, Ta, Nb and Mo, and 0.9 <x<1.2, 0.8<y<1, 0<z<0.8, 0<w<0.05, 0≤v≤0.2이다.)

[0153] In another embodiment, in the above lithium composite metal oxide, in the above chemical formula 3, M1 may be Mn, and although not particularly limited, when the sum of Mn and Fe atoms is 1, Mn may be 0.4 to 0.6.

[0154] The lithium composite metal oxide represented by the above chemical formulas 3 and 4 may be preferred because it can produce a dry electrode having higher electrical conductivity, but there is no particular limitation on this as long as the mechanical properties can be improved by using the acrylic elastic particles described above.

[0155] In one embodiment of the present disclosure, the fluorine-based resin particles may be in a particle state including a fluorine-based resin, and the fluorine-based resin may be a fluorine-based polymer that is polymerized by including one or more fluorine-based monomers selected from, but not limited to, vinylidene difluoride, vinyl fluoride, chlorotrifluoroethylene, tetrafluoroethylene, perfluoroalkyl vinyl ether, and hexafluoropropylene, as long as it is capable of being fiberized.

[0156] In another aspect of the present disclosure, the fluorinated monomer may be one or more perfluoro monomers selected from tetrafluoroethylene, perfluoroalkyl vinyl ether, and hexafluoropropylene.

[0157] The above fluorine-based polymer can have high heat resistance, excellent fiberization properties, and excellent binder properties, and in particular, due to excellent mutual complementarity with the acrylic elastomer particles described above, it has even better binder properties and excellent fiberization properties, and therefore can be particularly usefully used as a binder for electrodes, but this is not necessarily limited thereto.

[0158] As one embodiment of the present disclosure, the fluorine-based polymer is not particularly limited as long as it does not impair the properties of the electrode mixture and dry electrode to be manufactured, but as a non-limiting example, it may be polymerized by further including an α-olefin-based monomer that does not contain one or two or more fluorine substituents selected from ethylene, propylene, n-butylene, and methyl methacrylate.

[0159] The above fluorine-based polymer may be preferably a single polymer of the fluorine-based monomer described above to achieve excellent binder properties, but may further include the α-olefin-based monomer described above as long as it does not impair the physical properties of the electrode mixture.

[0160] As an example, when the fluorine-based polymer is a copolymer further including an α-olefin-based monomer, the fluorine-based monomer polymerization unit may be 70 wt% or more with respect to 100 wt% of the total polymerization units, and in another embodiment, it may be 80 wt% or more, or 90 wt% or more, and although the upper limit is not limited, it may be less than 100 wt%, or 99 wt% or less.

[0161] The above fluorine-based polymer may be polytetrafluoroethylene, and may be polytetrafluoroethylene, but is not necessarily limited thereto.

[0162] As one aspect of the present disclosure, the fluorine-based resin particles may further include one or more additives selected from a plasticizer, an emulsifier, a heat stabilizer, and a lubricant, as long as the additives do not impair the physical properties of the core-shell particles being manufactured.

[0163] The above fluorine-based resin particles may further include additives to improve the properties of the electrode mixture being manufactured, such as the applicability and adhesiveness, and the heat resistance and chemical resistance of the dry electrode, but this is not necessarily limited thereto.

[0164] In one embodiment of the present disclosure, the fluorine-based resin particles may have an average particle diameter (D50) of 0.01 to 50 ㎛, and in another embodiment, may have an average particle diameter of 0.05 to 50 ㎛, 0.1 to 50 ㎛, 0.1 to 30 ㎛, 0.1 to 20 ㎛, 0.1 to 10 ㎛, 0.1 to 5 ㎛, 0.1 to 1 ㎛, or 0.1 to 0.5 ㎛.

[0165] Fluorine resin particles having an average particle diameter (D50) in the above range can be mixed with acrylic elastic particles with high dispersibility, and the manufactured electrode mixture can have better binder properties for the electrode active material, so it may be preferred, but this is not necessarily limited.

[0166] As one embodiment of the present disclosure, the fluorine-based resin particles may be manufactured by emulsifying the acrylic elastic material in the same manner as the manufacturing method described above and drying the emulsion manufactured by emulsifying the material. However, since this is a known technology and many commercialized products have already been disclosed, a detailed description thereof will be omitted.

[0167] In one embodiment of the present disclosure, the electrode mixture may contain 0.1 to 30 parts by weight of fluorine-based resin particles based on 100 parts by weight of the electrode active material, and in another embodiment, it may contain 0.1 to 20 parts by weight, 0.1 to 15 parts by weight, 0.1 to 10 parts by weight, 0.1 to 7 parts by weight, 0.1 to 5 parts by weight, 0.5 to 5 parts by weight, or 1 to 5 parts by weight.

[0168] An electrode mixture containing fluorine-based resin particles in the above range of contents may be preferred because it has excellent binder properties and a dry electrode manufactured by including the same may have even better mechanical properties. However, this is not necessarily limited as long as the manufactured dry electrode satisfies the target properties.

[0169] An electrode mixture containing fluorine-based resin particles in the above range of contents may be preferred because it has excellent binder properties and a dry electrode manufactured by including the same may have even better mechanical properties. However, this is not necessarily limited as long as the manufactured dry electrode satisfies the target properties.

[0170] In one embodiment of the present disclosure, the electrode mixture may further include 5 parts by weight or less of a conductive material with respect to 100 parts by weight of an electrode active material in terms of having better ion conductivity, and in another embodiment, it may include 3 parts by weight or less, 2 parts by weight or less, or 1 part by weight or less, and although the lower limit is not limited, it may not be included, and may also be 0.1 part by weight or more.

[0171] The above-mentioned acrylic elastic particles can not only improve the excellent binder property of the electrode active material possessed by the fluorine-based resin particles, but also improve the excellent binder property of the fluorine-based resin particles for the conductive material, so that even if an electrode mixture is manufactured by further including a conductive material, a dry electrode having excellent mechanical properties can be manufactured.

[0172] In addition, the above electrode mixture may be preferred because it further includes a conductive material, so that the manufactured dry electrode can have better ionic conductivity, but this is not necessarily limited as long as it does not impair the physical properties of the electrode mixture.

[0173] The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and examples thereof include one or more selected from the group consisting of graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as fluorinated carbon, aluminum, and nickel powders; conductive whiskeys such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and polyphenylene derivatives.

[0174] In one embodiment of the present disclosure, when the electrode mixture comprises 4 to 6 parts by weight of fluorine-based resin particles and 0.5 to 1.5 parts by weight of acrylic elastomer particles for 100 parts by weight of electrode active material, the energy required for processing at 150°C and 15 rpm at a fill factor of 90% of a batch mixer may be 120 Nm or less.

[0175] That is, the electrode mixture can not only improve the mechanical properties of a dry electrode manufactured by including acrylic elastic particles, but can also have excellent processability in the processing performed to manufacture a dry electrode, and thus can be preferred.

[0176] The present disclosure can provide a dry film manufactured by including the above electrode mixture.

[0177] The above dry electrode can be manufactured in various forms such as a film type, fiber type, or rod type by processing the electrode mixture described above, or can be manufactured by coating the electrode mixture described above on an electrode current collector.

[0178] As one aspect of the present disclosure, the dry electrode may have the following mechanical properties when it contains 4 to 6 parts by weight of an electrode mixture and 0.5 to 1.5 parts by weight of acrylic elastic particles for 100 parts by weight of an electrode active material.

[0179] In one embodiment of the present disclosure, the dry electrode may have a tensile strength at break measured by ISO 527-2 of 2.5 MPa or more, preferably 3 MPa or more, 3.5 MPa or more, more preferably 4.0 MPa or more or 4.5 MPa or more, and although the upper limit is not limited, it may be 5.5 MPa or less or 5.0 MPa or less.

[0180] In one aspect of the present disclosure, the dry electrode may have an elongation at break measured by ISO 527-2 of 10% or more, preferably 12% or more, more preferably 15% or more, and, although not limited to an upper limit, 20% or less.

[0181] In one aspect of the present disclosure, the dry electrode may have a Young's modulus measured by ISO 527-2 of 50 to 100 MPa, preferably 60 to 100 MPa, and more preferably 70 to 100 MPa.

[0182] Since the above dry electrode has a tensile strength at break, elongation at break, and Young's modulus within the ranges described above, it is not easily broken by external force compared to a dry film manufactured including a conventional electrode compound.

[0183] Therefore, the secondary battery including the above dry electrode has superior stability and superior battery performance compared to conventional secondary batteries, and can maintain the initial excellent performance of the secondary battery for a long period of time.

[0184] The present disclosure will be described in more detail through the following examples. However, the following examples are merely references for further illustrating the present disclosure and are not intended to limit the present disclosure, which may be implemented in various forms. Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Furthermore, the terminology used in the description of this disclosure is solely for the purpose of effectively describing specific embodiments and is not intended to limit the present disclosure.

[0185] [measurement method]

[0186] 1. Measurement of average particle size (D50)

[0187] The particles were measured using a laser diffraction particle size distribution measuring device (Malvern, MASTERSIZER 3000 hydro), and the average particle diameter and Span value (average particle distribution width) were measured based on the wet measurement method. The average particle diameter was the D50 value, which is the average particle diameter by volume-based measurement (when Dn means the diameter of the particle corresponding to n% in terms of integrated fraction, "D50" corresponds to 50% in terms of integrated fraction in terms of volume). Afterwards, the particles were photographed with a scanning electron microscope (SEM) to confirm that they were similar to the average particle diameter (D50) of the particles.

[0188] 2. Mechanical property measurement

[0189] Measurements were made in accordance with ISO 527-2. Measurement samples were made using a universal testing machine (UTM, Zwick). Measurement samples were manufactured with a width of 10 mm and measured in the machine direction (MD) at a tensile speed of 50 mm / min. The measured results were expressed as tensile strength, elongation at break, and 100% modulus.

[0190] 3. Cross-linking measurement

[0191] After drying the emulsion of the manufactured acrylic elastic particles in an oven at 80°C, 3 g of the manufactured acrylic elastic particles were chopped and placed in a Soxhlet extractor. Dichloromethane (DCM), an organic solvent, was added to the Soxhlet extractor and heated to 100°C. The acrylic elastic particles were continuously exposed to the organic solvent for 3 hours, dried in an oven at 120°C for 3 hours, and the weight was measured. The weight before and after evaluation was calculated using the following formula to determine the degree of crosslinking.

[0192] [Formula 1]

[0193]

[0194] 4. Measurement of glass transition temperature

[0195] The manufactured acrylic elastomer particles were measured using DSC (differential scanning calorimetry, TA, Q20 DSC). The heating condition was 10 ℃, and after 2 cycles of measurement, the glass transition temperature was measured at the second inflection point using the half Cp method.

[0196] 5. Processability Measurement

[0197] The electrode mixtures manufactured in the following examples and comparative examples were ground into powder using a blender, and the manufactured powders were kneaded by filling 90% of the fill factor of a batch mixer (Brabender, mixer 50) at an internal temperature of 150°C and a rotation speed of 15 rpm for 3 minutes. At this time, the maximum torque of the energy for rotating the mixer's rotor was recorded.

[0198] Manufacturing of acrylic elastomer particles

[0199] [Example 1]

[0200] In a 1 L reactor, 738.0 g of deionized water and 144.0 g of n-butylacrylate (n-BA) were charged, 11.5 g of 1,4-butadiol dimethyl acrylate (BDMA) as a crosslinking agent, 3.2 g of Tergitol TMN-100X from DOW and 2.88 g of RS610-S25 from Solvay as fluidizing agents, and 0.72 g of ammonium persulfate as an initiator. Thereafter, the temperature of the reactor was increased to 80 ° C. and reacted for 3 hours, and then cooled to room temperature to prepare an acrylic elastic particle emulsion containing acrylic elastic particles. The prepared emulsion was dried in an 80 ° C. oven to obtain acrylic elastic particles.

[0201] The above acrylic elastic particles were measured using the above measurement method, and their physical properties are shown in Table 1 below.

[0202] [Example 2]

[0203] In the above Example 1, acrylic elastomer particles were prepared in the same manner as in Example 1 except that 4.0 g of 1,4-butadiol dimethyl acrylate (BDMA) was included.

[0204] The above acrylic elastic particles were measured using the above measurement method, and their physical properties are shown in Table 1 below.

[0205] [Example 3]

[0206] In the above Example 1, acrylic elastomer particles were prepared in the same manner as in Example 1 except that 7.0 g of 1,4-butadiol dimethyl acrylate (BDMA) was included.

[0207] The above acrylic elastic particles were measured using the above measurement method, and their physical properties are shown in Table 1 below.

[0208] [Example 4]

[0209] In the above Example 1, acrylic elastomer particles were prepared in the same manner as in Example 1 except that 14.0 g of 1,4-butadiol dimethyl acrylate (BDMA) was included.

[0210] The above acrylic elastic particles were measured using the above measurement method, and their physical properties are shown in Table 1 below.

[0211] [Example 5]

[0212] In the above Example 1, acrylic elastomer particles were prepared in the same manner as in Example 1 except that 28.0 g of 1,4-butadiol dimethyl acrylate (BDMA) was included.

[0213] The above acrylic elastic particles were measured using the above measurement method, and their physical properties are shown in Table 1 below.

[0214] [Example 6]

[0215] Acrylic elastic particles were manufactured in the same manner as in Example 1 above, except that 130.0 g of n-butylacrylate (n-BA) and 14.4 g of 2-hydroxyethyl methacrylate were used instead of 144.0 g of n-butylacrylate (n-BA).

[0216] The above acrylic elastic particles were measured using the above measurement method, and their physical properties are shown in Table 1 below.

[0217] [Example 7]

[0218] In the above Example 1, after emulsion polymerization, the emulsion in which the emulsion polymerized acrylic elastomer particles were dispersed was maintained at 75°C, and 183.86 g of a monomer mixture consisting of 146.88 g of methyl methacrylate (MMA), 36.72 g of butyl acrylate (nBA), and 0.26 g of normal octyl mercaptan was added dropwise to the reactor over 15 minutes. 15 minutes after the addition of the monomer mixture, 68.4 g of distilled water and 0.92 g of an aqueous potassium persulfate solution were added dropwise to the reactor over about 10 minutes. After the polymerization reaction was carried out for 3 hours from the end of the addition of potassium persulfate, the mixture was cooled to 30°C to obtain a white emulsion. Afterwards, the manufactured white emulsion was dried in an oven at 80°C, and acrylic elastomer particles having a resin shell layer formed thereon (core-shell of acrylic elastomer core-acrylic resin shell layer) were obtained.

[0219] The properties of the acrylic elastic particles having the above resin shell layer formed were measured using the above measurement method, and are shown in Table 1 below.

[0220] [Comparative Example 1]

[0221] In the above Example 1, acrylic elastomer particles were prepared in the same manner as above, except that 1.0 g of 1,4-butadiol dimethyl acrylate (BDMA) was included.

[0222] The above acrylic elastic particles were measured using the above measurement method, and their physical properties are shown in Table 1 below.

[0223] Particle type Crosslinking (%) Average particle size (D50) (㎛) Span Glass transition temperature (℃) Example 1 Acrylic elastomer 88 0.114 1.29-24.8 Example 2 Acrylic elastomer 500.096 1.21-28.1 Example 3 Acrylic elastomer 700.102 1.14-26.9 Example 4 Acrylic elastomer 95 0.111 1.31-22.4 Example 5 Acrylic elastomer 99 0.120 1.20-21.6 Example 6 Acrylic elastomer 85 0.122 1.15-8.0 Example 7 Acrylic elastomer (core) 87 0.118 1.20-22.9 Acrylic resin (Shell) 00.133 (shell layer) Including) 1.1879.1 Comparative example 1 Acrylic elastomer 260.1091.34-26.7

[0224] Electrode compound manufacturing

[0225] [Example 8]

[0226] An electrode mixture was prepared by mixing 96 g of an active material (NCM622 (nickel / cobalt / manganese = 6 / 2 / 2 wt%)) and 1 g of a conductive material (Ketjen Black EC-600D) into a pre-mixed mixture, 4 g of polytetrafluoroethylene powder (Teflon, 601X) and 1 g of the acrylic elastomer particles of Example 1.

[0227] Afterwards, the electrode mixture was dispersed at 24,000 rpm using a blender (Kochstar, KSEBD-1500), and once the dispersion was complete, it was kneaded at an internal temperature of 150°C and a rotation speed of 15 rpm for 3 minutes using a batch mixer (HAAKE, Rheomix 600). The kneaded sample was ground using the blender to produce a powder. The powder was pressed into a film using a 2-roll mill (Kmtech, KRM-80) at room temperature, a rotation speed of 10 rpm, and pressure.

[0228] The above film was measured using the above measurement method, and its physical properties are listed in Table 2 below.

[0229] [Example 9]

[0230] In the above Example 8, an electrode mixture and a film were manufactured in the same manner as in Example 1, except that the acrylic elastomer particles of Example 2 were used instead of the acrylic elastomer particles of Example 1.

[0231] The above film was measured using the above measurement method, and its physical properties are listed in Table 2 below.

[0232] [Example 10]

[0233] In the above Example 8, an electrode mixture and a film were manufactured in the same manner as in Example 3, except that the acrylic elastomer particles of Example 3 were used instead of the acrylic elastomer particles of Example 1.

[0234] The above film was measured using the above measurement method, and its physical properties are listed in Table 2 below.

[0235] [Example 11]

[0236] In the above Example 8, an electrode mixture and a film were manufactured in the same manner as in Example 4, except that the acrylic elastomer particles of Example 4 were used instead of the acrylic elastomer particles of Example 1.

[0237] The above film was measured using the above measurement method, and its physical properties are listed in Table 2 below.

[0238] [Example 12]

[0239] In the above Example 8, an electrode mixture and a film were manufactured in the same manner as in Example 5, except that the acrylic elastomer particles of Example 5 were used instead of the acrylic elastomer particles of Example 1.

[0240] The above film was measured using the above measurement method, and its physical properties are listed in Table 2 below.

[0241] [Example 13]

[0242] In the above Example 8, an electrode mixture and a film were manufactured in the same manner as in Example 6, except that the acrylic elastomer particles of Example 6 were used instead of the acrylic elastomer particles of Example 1.

[0243] The above film was measured using the above measurement method, and its physical properties are listed in Table 2 below.

[0244] [Example 14]

[0245] In the above Example 8, an electrode mixture and a film were manufactured in the same manner as in Example 7, except that the acrylic elastomer particles of Example 7 were used instead of the acrylic elastomer particles of Example 1.

[0246] The above film was measured using the above measurement method, and its physical properties are listed in Table 2 below.

[0247] [Comparative Example 2]

[0248] In the above Example 8, an electrode mixture and a film were manufactured in the same manner as in Comparative Example 1, except that the acrylic elastomer particles of Example 1 were used instead of the acrylic elastomer particles of Example 1.

[0249] The above film was measured using the above measurement method, and its properties are shown in Table 2 below.

[0250] [Comparative Example 3]

[0251] In the above Example 1, an electrode mixture and a film were manufactured in the same manner as in Example 1, except that the acrylic elastomer particles of Example 1 were not included and 5 g of polytetrafluoroethylene powder (Tefon, 601X) was used.

[0252] The above film was measured using the above measurement method, and its properties are shown in Table 2 below.

[0253] Tensile strength at break (MPa) Elongation at break (%) Modulus (MPa) Workability (Nm) Example 82.8110.772.0110 Example 92.6618.260.5106 Example 102.7114.364.1105 Example 112.789.178.4109 Example 122.808.180.8111 Example 133.1112.184.1112 Example 142.5410.170.1102 Comparative example 21.7430.121.1101 Comparative example 31.925.01147.5124

[0254] It was confirmed that the electrode mixtures of Examples 8 to 14 above had excellent binder properties, and the manufactured dry electrode films had a tensile strength at break of 2.5 MPa or more, an elongation at break of 10% or more, and a modulus of 50 to 100 MPa.

[0255] In addition, it was confirmed that the electrode mixtures of Examples 8 to 14 required very low energy of 120 Nm or less for stirring at 10 rpm during the kneading process, compared to the comparative examples. This suggests that the electrode mixtures of Examples 8 to 14 can prevent breakdown due to the load of the stirrer when kneading in large quantities.

[0256] In contrast, it was confirmed that the dry electrodes manufactured including the electrode mixtures of Comparative Examples 2 and 3 had poor mechanical properties compared to the dry electrodes of Examples 8 to 14. In addition, referring to Table 2 above, it was confirmed that the electrode mixtures of Comparative Examples 2 and 3 had poor processability because the energy for kneading at 10 rpm exceeded 120 Nm.

[0257] Therefore, according to one aspect of the present disclosure, the acrylic elastic particles can not only improve the binder properties of an electrode active material due to excellent mutual complementarity with the fluorine resin particles, but also, since the mechanical properties of a dry electrode manufactured including the acrylic elastic particles are excellent, breakage due to external force can be prevented, and thus a secondary battery having excellent performance and being able to maintain excellent performance for a long period of time can be manufactured.

[0258] As described above, the present disclosure has been described by specific matters and limited examples and comparative examples, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art to which the present invention pertains can make various modifications and variations based on this description.

[0259] Therefore, the idea of ​​the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the claims are considered to fall within the scope of the idea of ​​the present invention.

Claims

1. As an acrylic elastic particle included as a binder additive in an electrode mixture, The above acrylic elastic particles are C1-C 12 It is manufactured by including an alkyl-substituted (meth)acrylate and a crosslinking agent containing two or more unsaturated groups, Acrylic elastic particles having a cross-linking degree of 50% or more calculated by the following formula 1. [Formula 1] In the above equation 1, W0 is the dry mass of the initial acrylic elastomer particles, W1 is the dry mass of acrylic elastic particles heated in dichloromethane at 100 ℃ for 3 hours.

2. In paragraph 1, The above acrylic elastic particles are acrylic elastic particles having a glass transition temperature of -40 to 0 ℃.

3. In paragraph 1, C1-C above 12 An acrylic elastic particle comprising an alkyl-substituted (meth)acrylate and n-butylacrylate.

4. In paragraph 1, The above acrylic elastomer particles are acrylic elastomer particles having a cross-linking degree of 70 to 90%.

5. In paragraph 1, The above acrylic elastomer particles are core-shell type acrylic elastomer particles further including a continuous non-crosslinked acrylic resin shell layer on the surface.

6. In paragraph 5, The above core-shell type acrylic elastomer particles are acrylic elastomer particles in which the mass of the acrylic resin shell layer is 50 wt% or less with respect to the total mass.

7. In paragraph 5, The above acrylic resin shell layer is an acrylic elastic particle that is a methyl methacrylate homopolymer or a methyl methacrylate copolymer.

8. In paragraph 1, The above acrylic elastic particles are C2-C containing hydroxyl groups. 12 Acrylic elastic particles manufactured by further including an alkyl-substituted (meth)acrylic monomer.

9. In paragraph 8, The above acrylic elastic particles contain C2-C containing hydroxyl groups with respect to the total amount of monomers input during manufacturing. 12 Acrylic elastic particles further comprising 30 wt% or less of an alkyl-substituted (meth)acrylic monomer.

10. In paragraph 1, The above acrylic elastic body particles are manufactured by further including an α-olefin monomer.

11. In paragraph 1, The above acrylic elastic particles are acrylic elastic particles having an average particle diameter (D50) of 0.01 to 50 ㎛.

12. An electrode mixture comprising an acrylic elastomer particle, a fluorine-based resin particle, and an electrode active material selected from any one of clauses 1 to 11.

13. In paragraph 12, The above fluorine-based resin particles are an electrode composite polymerized by including one or more fluorine-based monomers selected from vinylidene difluoride, vinyl fluoride, chlorotrifluoroethylene, tetrafluoroethylene, perfluoroalkyl vinyl ether, and hexafluoropropylene.

14. In paragraph 12, The above fluorine-based resin particles are electrode mixtures having an average particle diameter (D50) of 0.01 to 50 ㎛.

15. In paragraph 12, The electrode mixture is an electrode mixture containing 0.1 to 30 parts by weight of fluorine-based resin particles for 100 parts by weight of electrode active material.

16. In paragraph 12, The electrode mixture comprises 0.01 to 10 parts by weight of acrylic elastic particles per 100 parts by weight of electrode active material.

17. In paragraph 12, The electrode mixture is an electrode mixture that further contains 5 parts by weight or less of a conductive material for 100 parts by weight of an electrode active material.

18. In paragraph 12, The electrode mixture is an electrode mixture that, when containing 4 to 6 parts by weight of fluorine-based resin particles and 0.5 to 1.5 parts by weight of acrylic elastomer particles for 100 parts by weight of electrode active material, fills 90% of the fill factor of a batch mixer and processes the mixture at 150°C and 15 rpm, and has an energy of 120 Nm or less.

19. A dry electrode manufactured including the electrode mixture of Article 12.

20. In paragraph 19, The above dry electrode is a dry electrode having the following mechanical properties measured by ISO 527-2 when it contains 4 to 6 parts by weight of fluorine-based resin particles and 0.5 to 1.5 parts by weight of acrylic elastomer particles for 100 parts by weight of electrode active material. (1) Tensile strength at break of 2.5 MPa or more (2) Breaking elongation of 10% or more (3) Modulus of 50 to 100 MPa

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