Electrode comprising non-reducible ceramic particles, and secondary battery comprising same

Abstract

Disclosed in the present specification is an anode for a secondary battery, comprising: an anode current collector; and an anode active material layer formed on at least one surface of the anode current collector, wherein the anode active material layer comprises anode active material particles and electrode additive particles, the anode active material particles and the electrode additive particles being dispersed on the anode active material layer and the electrode additive particles comprising non-reducible ceramic particles, wherein the non-reducible ceramic particles comprise at least one of boehmite, magnesium oxide (MgO) and alumina (Al2O3).

Description

Electrode comprising non-reducing ceramic particles and secondary battery comprising the same

[0001] Cross-citation with related application(s)

[0002] The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0129006 filed September 24, 2024; and Korean Patent Application No. 10-2025-0137199 filed September 23, 2025, and all contents disclosed in the documents of said Korean patent applications are incorporated herein as part of the specification.

[0003] This specification discloses an electrode comprising non-reducing ceramic particles and a secondary battery comprising the same.

[0004] With the recent rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for rechargeable batteries—which are small, lightweight, and relatively high-capacity—is increasing rapidly. In particular, lithium-ion batteries are gaining prominence as power sources for portable devices due to their lightweight nature and high energy density. Consequently, active research and development efforts are underway to improve the performance of lithium-ion batteries.

[0005] Meanwhile, research aimed at improving the rapid charge / discharge performance of secondary batteries mainly consists of i) research to improve the ion conductivity of the electrolyte and ii) research to improve the film at the electrolyte / active material interface.

[0006] However, while the ionic conductivity of the electrolyte and the electrolyte / active material interface film acts as an important factor in the actual lithium deinsertion / insertion process within the active material, the concentration of free lithium ions at the interface is also an important factor when inserting lithium ions into the active material.

[0007] Meanwhile, research is being conducted to improve the rapid charging characteristics of the anode, including 1) methods of modifying the anode active material, 2) methods of changing the electrolyte composition, and 3) methods of controlling the anode film. However, these methods may have a negative impact on the charge / discharge capacity, lifespan, and storage characteristics of existing batteries. In particular, methods of modifying the anode active material or changing the electrolyte composition have problems that cause fatal side reactions to key factors such as active material swelling and storage gas generation.

[0008] Therefore, there is an increasing need for research to improve the rapid charging characteristics of existing electrolyte / anode active materials in the same battery design, while simultaneously controlling the possibility of causing the aforementioned side reactions and improving rapid charging characteristics.

[0009] Accordingly, the inventors intend to improve rapid charging characteristics by dispersing specific non-reducing ceramic particles within the electrode to control the ion distribution characteristics at the active material / electrolyte interface and to control the cathode film.

[0010] Hereinafter, electrodes for secondary batteries, etc., according to specific embodiments of the present invention will be described.

[0011] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0012] The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0013] In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0014]

[0015] Negative electrode for secondary batteries

[0016] In one embodiment of the present invention, a negative electrode for a secondary battery is provided, comprising: a negative electrode current collector; and a negative electrode active material layer formed on at least one surface of the negative electrode current collector; wherein the negative electrode active material layer comprises negative electrode active material particles and electrode additive particles, and the negative electrode active material particles and electrode additive particles are dispersed on the negative electrode active material layer, and the electrode additive particles comprise non-reducing ceramic particles, and the non-reducing ceramic particles comprise one or more of boehmite, magnesium oxide (MgO), and alumina (Al2O3). The electrode for the secondary battery may have performance improvements similar to or greater than those of the case in which oxide-based solid electrolyte particles are used by using non-reducing ceramics having surface charges instead of oxide-based solid electrolyte particles containing a lithium source as electrode additive particles. For example, the non-reducing ceramic particles may accelerate the desolvation process. In particular, ceramics can form intermolecular forces with electrolyte components, solvents, anions, and cations, thereby accelerating the desolvation process.

[0017] In an exemplary embodiment, the electrode additive particles can increase the concentration of free lithium ions on the surface of the electrode active material. Meanwhile, the electrode additive particles may include a solid electrolyte and / or a non-reducing ceramic. For example, the electrode additive particles may include one or more of boehmite, magnesium oxide (MgO), and alumina (Al2O3) as non-reducing ceramic particles. On the other hand, zinc oxide (ZnO) may be difficult to apply due to its reducing properties.

[0018] For example, the solid electrolyte may include one or more lithium metal oxides or lithium metal phosphates selected from Nasicon-type solid electrolytes, Lisicon-type solid electrolytes, Garnet-type solid electrolytes, Perovskite-type solid electrolytes, and LiPON-type solid electrolytes, and more specific examples may include one or more selected from the group consisting of LAGP (lithium aluminum germanium phosphate)-based compounds, LLZO (lithium lanthanum zirconium oxide)-based compounds, LATP (lithium aluminum titanium phosphate)-based compounds, LLZTO (lithium lanthanum zirconium tantalum oxide)-based compounds, LLTO (lithium lanthanum titanium oxide)-based compounds, LSTP (lithium silicon titanium phosphate)-based compounds, and LGPO (lithium germanium phosphate)-based compounds.

[0019] In an exemplary embodiment, the electrode additive particles may be included in an amount of 0.5 to 3 weight percent based on the total weight of the electrode. If the content is less than 0.5, the desolvation acceleration reaction by the oxide may have a low contribution to the improvement of axial power, and if it exceeds 3 weight percent, there may be a decrease in the reaction area by the oxide and a decrease in output performance due to structural changes.

[0020] In a present exemplary embodiment, the electrode additive particles may have an average diameter of 300 nm or less. Specifically, the electrode additive particles may have an average diameter in the range of 100 to 300 nm. As the particle size range and / or content range of the electrode additive particles are optimized, the concentration of free lithium ions on the surface of the electrode active material can be increased. Meanwhile, if the particle size range of the electrode additive particles becomes excessively small, such as less than 100 nm, the surface of the nanoceramic particles may be covered by the polymer binder, and in such a case, the performance improvement characteristics due to the interaction between the nanoceramic and the liquid electrolyte may not be exhibited. These negative characteristics can be avoided by increasing the content of the non-reducing ceramic (electrode additive particles), but it is not desirable to increase it to more than 3 wt% due to negative performance associated with increasing the content of the non-reducing ceramic. Therefore, the effects according to the present invention can be obtained in a combination in which the particle size range and content range of the electrode additive particles include an average diameter in the range of 100 to 300 nm and 0.5 to 3 wt%, respectively.

[0021] In an exemplary embodiment, the electrode additive particles may have an absolute zeta potential of 20 mV or more. For example, the electrode additive particles may have an absolute zeta potential of 30 mV or more. In this range, the strength of the electrostatic attraction is high, which can increase the concentration of free lithium ions on the surface of the active material.

[0022] In an exemplary embodiment, the cathode active material particles may comprise one or more materials selected from the group consisting of carbonaceous materials, metallic compounds, and metal oxides.

[0023] At this time, a compound capable of reversible intercalation and deintercalation of lithium may be used as the negative electrode active material. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Sb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; metal oxides capable of doping and dedoping lithium such as SiOβ (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the metallic compound and the carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Furthermore, low-crystallinity carbon and high-crystallinity carbon may both be used as the carbonaceous material. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0024] In an exemplary embodiment, the negative electrode active material layer may further include a binder and a conductive material, in addition to the negative electrode active material described above. The above binder is a component that assists in the bonding of the negative electrode active material and the conductive material, etc., and in the bonding to the current collector, and is, for example, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVdF / HFP), polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, polyethylene, polyethylene oxide, alkylated polyethylene oxide, polypropylene, polymethyl (meth)acrylate, polyethyl (meth)acrylate, polytetrafluoroethylene (PTFE), polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, polyvinylpyrrolidone, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene-diene monomer (EPDM) rubber, sulfonated EPDM rubber, styrene-butylene rubber, fluororubber, carboxymethylcellulose (CMC), starch, One or more selected from the group consisting of hydroxypropyl cellulose, regenerated cellulose, and mixtures thereof may be used, but are not necessarily limited thereto.

[0025] The above binder may be used in an amount of 1 to 50 parts by weight or 3 to 15 parts by weight per 100 parts by weight of the total weight of the negative electrode. As a result, the adhesion between the negative electrode active material and the current collector and the capacity characteristics of the secondary battery can be maintained excellently.

[0026] In addition, the conductive material included in the above-mentioned cathode is not particularly limited as long as it has excellent electrical conductivity without causing side reactions in the internal environment of the lithium secondary battery or causing chemical changes in the battery, and can be used as a representative example, graphite or conductive carbon, for example, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black; carbon-based material having a crystal structure of graphene or graphite; conductive fiber such as carbon fiber or metal fiber; fluorinated carbon; metal powder such as aluminum powder or nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive oxide such as titanium oxide; and conductive polymer such as polyphenylene derivative; can be used alone or in a mixture of two or more types, but is not necessarily limited thereto.

[0027] The above conductive material may be used in an amount of 0.5 to 50 parts by weight, or 1 to 30 parts by weight, per 100 parts by weight of the total weight of the cathode. By doing so, the electrochemical properties, such as conductivity and capacity of the cathode and the lithium secondary battery, can be maintained in excellent condition.

[0028] In addition, a filler may be optionally added to the above-mentioned cathode as a component that inhibits expansion. Such a filler is not particularly limited as long as it can inhibit the expansion of the electrode without causing chemical changes in the battery, and for example, olifin-based polymers such as polyethylene and polypropylene; fibrous materials such as glass fibers and carbon fibers; etc. may be used.

[0029] In addition, the above-mentioned cathode current collector may be platinum (Pt), gold (Au), palladium (Pd), iridium (Ir), silver (Ag), ruthenium (Ru), nickel (Ni), stainless steel (STS), copper (Cu), molybdenum (Mo), chromium (Cr), carbon (C), titanium (Ti), tungsten (W), ITO (In-doped SnO2), FTO (F-doped SnO2), and alloys thereof, and a copper (Cu) or stainless steel surface treated with carbon (C), nickel (Ni), titanium (Ti), or silver (Ag), but is not necessarily limited thereto. The form of the cathode current collector may be a foil, film, sheet, punched, porous body, foam, etc.

[0030] In addition, in an exemplary embodiment, the cathode active material particles may have an average diameter in the range of 1 to 20 μm, and the cathode active material particles may have a content of 50 to 99 weight% or 95 weight% or more with respect to the total weight of the cathode active material layer.

[0031] In an exemplary embodiment, all or at least part of the outer surface of the cathode active material particles may be coated with the electrode additive particles.

[0032] In addition, the electrode for the secondary battery can have a charge / discharge capacity of 30 mAh / g or less at 0.01-1.5V relative to Li.

[0033]

[0034] secondary battery

[0035] In another embodiment of the present invention, a secondary battery is provided, comprising: a positive electrode; a negative electrode for the secondary battery described above; and an electrolyte layer interposed between the positive electrode and the negative electrode.

[0036] Meanwhile, in the lithium secondary battery of the other embodiment described above, the above-described positive electrode can be manufactured by, for example, by dispersing and mixing the positive electrode active material, binder, and conductive material, etc., in a dispersion medium (solvent) to form a slurry, applying the slurry onto a positive electrode current collector, and then drying and rolling. At this time, the dispersion medium may use NMP (N-methyl-2-pyrrolidone), DMF (Dimethyl formamide), DMSO (Dimethyl sulfoxide), ethanol, isopropanol, water, and mixtures thereof, but is not necessarily limited thereto.

[0037] The above positive electrode active material is not particularly limited as long as it is a material capable of reversible insertion and extraction of lithium ions, and may include, for example, a lithium metal composite oxide containing one or more metal elements selected from the group consisting of Co, Mn, Ni, W, Cu, Fe, V, Cr, Ti, Zr, Zn, Al, In, Ta, Y, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg and Mo.

[0038] More specifically, as the positive electrode active material, a compound represented by any one of the following chemical formulas may be used. Li a A 1-b R b D2 (wherein 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li a E 1-b R b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b R b O 4-c D c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b R c D α(In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni 1-b-c Co b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Co b R c O 2-α Z2 (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni 1-b-c Mn b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b R c O 2-α Z2 (wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni b E c G d O2(wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5 and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn dGeO2(wherein 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5 and 0.001 ≤ e ≤ 0.1); Li a NiG b O2(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2(wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; and Li (3-f) J2(PO4)3(0 ≤ f ≤ 2).

[0039] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, V or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn or a combination thereof; Z is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, V or a combination thereof; Q is Ti, Mo, Mn or a combination thereof; T is Cr, V, Fe, Sc, Y or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0040] In addition, the above-described anode may further include a binder and a conductive material, etc., in addition to the anode active material described above. The above binder is a component that assists in the bonding of the positive active material and the conductive material, etc., and in bonding to the current collector, and is, for example, polyvinylidene fluoride (PVdF), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVdF / HFP), polyvinyl acetate, polyvinyl alcohol, polyvinyl ether, polyethylene, polyethylene oxide, alkylated polyethylene oxide, polypropylene, polymethyl (meth)acrylate, polyethyl (meth)acrylate, polytetrafluoroethylene (PTFE), polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, polyvinylpyrrolidone, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene-diene monomer (EPDM) rubber, sulfonated EPDM rubber, styrene-butylene rubber, fluororubber, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, One or more selected from the group consisting of regenerated cellulose and mixtures thereof may be used, but are not necessarily limited thereto.

[0041] The above binder may be used in an amount of 1 to 50 parts by weight or 3 to 15 parts by weight per 100 parts by weight of the total weight of the anode. As a result, the adhesion between the anode active material and the current collector and the capacity characteristics of the secondary battery can be maintained excellently.

[0042] In addition, the conductive material included in the above-mentioned cathode is not particularly limited as long as it does not cause side reactions in the internal environment of the lithium secondary battery and does not cause chemical changes in the battery while having excellent electrical conductivity. Representative examples include graphite or conductive carbon. For instance, graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, Denka black, thermal black, channel black, furnace black, lamp black; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; metal powders such as aluminum powder or nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive oxides such as titanium oxide; and conductive polymers such as polyphenylene derivatives may be used alone or in a mixture of two or more types, but is not necessarily limited thereto.

[0043] The above conductive material may be used in an amount of 0.5 to 50 parts by weight, or 1 to 30 parts by weight, per 100 parts by weight of the total weight of the anode. By doing so, the electrochemical properties, such as conductivity and capacity of the anode and the lithium secondary battery, can be maintained in excellent condition.

[0044] In addition, a filler may be optionally added to the anode as a component that inhibits expansion. Such a filler is not particularly limited as long as it can inhibit the expansion of the electrode without causing chemical changes in the battery, and for example, olifin-based polymers such as polyethylene and polypropylene; fibrous materials such as glass fibers and carbon fibers; etc. may be used.

[0045] In addition, the anode current collector may be platinum (Pt), gold (Au), palladium (Pd), iridium (Ir), silver (Ag), ruthenium (Ru), nickel (Ni), stainless steel (STS), aluminum (Al), molybdenum (Mo), chromium (Cr), carbon (C), titanium (Ti), tungsten (W), ITO (In-doped SnO2), FTO (F-doped SnO2), and alloys thereof, as well as aluminum (Al) or stainless steel surface-treated with carbon (C), nickel (Ni), titanium (Ti), or silver (Ag), but is not necessarily limited thereto. The form of the anode current collector may be a foil, film, sheet, punched, porous body, foam, etc.

[0046] Meanwhile, the liquid electrolyte included in the above electrolyte layer may include a non-aqueous organic solvent and a lithium salt. The type of non-aqueous organic solvent that can be used is not particularly limited, and any organic solvent known to be applicable to the electrolyte of a lithium-ion battery, etc., may be used. Examples of such organic solvents include one or more selected from the group consisting of carbonate-based solvents, ether-based solvents, nitrile-based solvents, phosphate-based solvents, and sulfone-based solvents.

[0047] More specifically, the carbonate-based solvent may include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, methyl propyl carbonate, ethyl methyl carbonate, ethyl propyl carbonate, or methyl(2,2,2-trifluoroethyl) carbonate, and the phosphate-based solvent may include trimethyl phosphate, triethyl phosphate, or 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphosphorane 2-oxide.

[0048] In addition, the above ether-based solvent may be a tetrahydrofuran derivative such as dibutyl ether, tetraglame, diglame, dimethoxyethane, or 2-methyl tetrahydrofuran, and the above nitrile-based solvent may be succinonitrile, adiponitrile, sebaconitrile, acetonitrile, or propionitrile. In addition, the above sulfone-based solvent may be dimethyl sulfone, ethylmethyl sulfone, or sulforane.

[0049] However, in terms of superior mechanical properties and safety of the composite electrolyte membrane, it is preferable to use a carbonate-based solvent, a sulfone-based solvent, or a phosphate-based solvent as the organic solvent, wherein at least a portion thereof can be cured together with the crosslinking polymer and exhibit flame retardancy. Furthermore, it is more preferable to use a solvent as the organic solvent that exhibits low volatility under curing conditions for the formation of the crosslinking polymer, for example, under thermal curing conditions of 60 to 80°C.

[0050] Meanwhile, as the lithium salt dissolved or dispersed in the above organic solvent, any lithium salt previously known to be applicable to the electrolyte of a lithium secondary battery, e.g., LiFSI (lithium bis(fluorosulfonyl)imide), LiTFSI (lithium bis(trifluoromethanesulfonyl)imide), LiCl, LiBr, LiI, LiClO4, LiBF4, LiPF6, LiB 10 Cl 10One or more selected from the group consisting of , LiCF3SO3, LiCF3CO2, LiC4BO8, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, (C2F5SO2)2NLi, (CF3SO2)3CLi, lithium chloroborane, lithium lower aliphatic carboxylate with 4 or fewer carbon atoms, lithium 4-phenylborate, and lithium imide may be used.

[0051] Such lithium salts may be included in the organic solvent of the liquid electrolyte at a concentration of 0.8 M to 4.0 M or 1.0 M to 2.0 M, and thereby the composite electrolyte membrane of one embodiment may exhibit excellent thermal stability and ionic conductivity.

[0052] Meanwhile, in the lithium secondary battery of the other embodiment described above, an electrolyte layer may be interposed between the positive electrode and the negative electrode, for example, in the form of a layered membrane or film. In this case, the electrolyte layer may also serve as a separator (i.e., electrically insulating the negative electrode and the positive electrode while allowing lithium ions to pass through). At this time, the electrolyte layer may be included in the secondary battery by being coated and attached in the form of a thin film on one surface of the positive electrode or the negative electrode. Additionally, the electrolyte layer may be interposed independently between the positive electrode and the negative electrode. Furthermore, the lithium secondary battery of the other embodiment described above may be a semi-solid battery that uses both a liquid electrolyte and a solid electrolyte.

[0053] In addition, when a porous separator is added to the electrolyte layer of the lithium secondary battery, such a separator may be used in the form of a sheet, multilayer film, microporous film, woven fabric, nonwoven fabric, etc., using olefin-based polymers such as polyethylene and polypropylene, glass fiber, etc., but is not necessarily limited thereto. However, it may be preferable to use porous polyethylene or porous glass fiber nonwoven fabric (glass filter) as the separator, and it may be even more preferable to use porous glass fiber nonwoven fabric as the separator. The separator may be an insulating thin film having high ion permeability and mechanical strength, and the pore diameter of the separator may generally be in the range of 0.01 to 10 μm, and the thickness may generally be in the range of 5 to 300 μm, but is not limited thereto.

[0054] Meanwhile, the lithium secondary battery of the other embodiment described above can be manufactured according to conventional methods in the field. For example, it can be manufactured by forming a composite electrolyte membrane, etc. between a positive electrode and a negative electrode, and optionally adding a porous separator, etc.

[0055] These lithium secondary batteries are not only applied to battery cells used as power sources for small devices, but are also particularly suitable for use as unit cells in battery modules that serve as power sources for medium and large devices.

[0056] As described above, the negative electrode for a secondary battery according to an embodiment of the present invention applies non-reducing ceramic particles as electrode additive particles to the negative electrode active material layer, thereby improving rapid charging characteristics while simultaneously controlling the possibility of causing the aforementioned side reaction, and can improve rapid charging characteristics in a battery design identical to that of the conventional electrolyte / negative electrode active material.

[0057] FIGS. 1a and 1b illustrate the results of measuring the charge and discharge capacity of a cell to which a negative electrode for a secondary battery according to an embodiment of the present invention is applied.

[0058] FIG. 2 illustrates the measurement results of the limit SOC by C-rate of a cell with a negative electrode for a secondary battery according to an embodiment of the present invention.

[0059] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily practice the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0060]

[0061] Example 1: Cathode with non-reducing ceramic particles (MgO)

[0062] A cathode slurry was prepared by mixing a natural / synthetic graphite blend with an average particle size (D50) of 10 μm as the cathode active material and magnesium oxide (MgO) with an average particle size (D50) of 300 nm as non-reducing ceramic particles in a weight ratio of 99:1. Carbon nanotubes were used as the conductive material and polyvinylidene fluoride (PVDF) as the binder, and added in a weight ratio of ceramic particles:binder:conductive material = 8:1:1 (Example 1-1). In addition, to measure the reduction capacity of the non-reducing ceramic particles, a slurry was prepared by mixing ceramic particles:binder:conductive material in a weight ratio of 8:1:1, excluding the cathode active material (Example 1-2).

[0063] Then, the above cathode slurry was applied to a copper current collector with a thickness of 20 μm, and then vacuum dried at 120°C for 24 hours. Next, a rolling process was carried out to form a cathode with a thickness of 80 μm.

[0064]

[0065] Example 2: Cathode with non-reducing ceramic particles (Al2O3)

[0066] A cathode with non-reducing ceramic particles was prepared in the same manner as in Example 1, except that alumina (Al2O3) was used instead of magnesium oxide as the non-reducing ceramic particles, and a cathode with added cathode active material (Example 2-1) and a cathode without added cathode active material (Example 2-2) were prepared, respectively.

[0067]

[0068] Comparative Example 1: Cathode without ceramic particles

[0069] A cathode with non-reducing ceramic particles was prepared in the same manner as in Example 1, except that non-reducing ceramic particles were not applied, and a cathode with cathode active material added (Comparative Example 1-1) and a cathode without cathode active material added (Comparative Example 1-2) were prepared, respectively.

[0070]

[0071] Comparative Example 2: Cathode with Reducing Ceramic Particles (LATP)

[0072] A cathode with non-reducing ceramic particles was prepared in the same manner as in Example 1, except that LATP with an average particle size (D50) of 300 nm was applied as a reducing ceramic particle instead of magnesium oxide (MgO) non-reducing ceramic particles. A cathode with added cathode active material (Comparative Example 2-1) and a cathode without added cathode active material (Comparative Example 2-2) were prepared, respectively.

[0073]

[0074] Comparative Example 3: Cathode with reducing ceramic particles (ZnO)

[0075] A cathode with non-reducing ceramic particles was prepared in the same manner as in Example 1, except that ZnO with an average particle size (D50) of 300 nm was used as the reducing ceramic particle instead of magnesium oxide (MgO) non-reducing ceramic particles. A cathode with added cathode active material (Comparative Example 3-1) and a cathode without added cathode active material (Comparative Example 3-2) were prepared, respectively.

[0076]

[0077] Experimental Example 1: Ceramic Reduction Capacity Test

[0078] The reduction capacity of non-reducing ceramic particles was measured. Coin cells were prepared using the following method to measure reducing ability.

[0079] 1) First, the cathode (Examples 1-1, 1-2, 2-1, 2-2, Comparative Examples 1-1, 1-2), polyethylene (PE) separator, and lithium metal were cut to 15, 19, and 13.762 pi, respectively. Then, starting from the bottom of the coin cell, the ceramic composite layer, separator, and lithium metal were stacked in that order, and 80 µl of electrolyte was injected. After that, a 1 mm thick stainless steel and a spring were placed sequentially, and the cap was closed to complete each coin cell.

[0080] 2) After manufacturing the coin cell, an impregnation period of 12 hours was performed, followed by discharge at a current of approximately 0.1C. The discharge capacity obtained through the above electrochemical evaluation was calculated from the weight of the ceramic in the ceramic composite layer and converted into capacity per weight (Discharge: Reaction in which lithium is released from lithium metal / Reaction in which the ceramic accepts lithium ions and electrons for reduction).

[0081] 3) Figures 1a and 1b illustrate the results of measuring the charge / discharge capacity of a cell with a cathode applied according to an embodiment of the present invention. In order to achieve the capacity, a reducing material must be formed in the form of a composite material through the reaction Li + Al2O3 → LiAl2O3. Therefore, in the case of samples excluding the cathode active material (Examples 1-2, 2-2, Comparative Example 1-2), such a reduction reaction is impossible, so the reduction capacity of the ceramic can be confirmed.

[0082] As a result, referring to Fig. 1a, it can be seen that the non-reducing ceramic particles have a charge / discharge capacity of 30 mAh / g or less at 0.01-1.5V relative to Li.

[0083] On the other hand, referring to Fig. 1b, it can be seen that in the case of Comparative Examples 2-1 and 3-1, which have reduced ceramic particles added, it is difficult to achieve the target capacity.

[0084]

[0085] Experimental Example 2: Rapid Charging Limit Test

[0086] A charge limit test was performed to determine the capacity at which Li metal dendrites are formed according to each charge rate and to set the charge limit capacity per rate.

[0087] 1) Monocells were manufactured by applying the cathodes of Example 1-1, Example 2-1, and Comparative Example 1-1, respectively.

[0088] First, the aforementioned non-reducing ceramic particle-applied cathode was prepared. For the fabrication of the anode, a lithium nickel-cobalt-manganese composite oxide (NCM 811; D50: 10 μm) containing 80 mol% nickel among the total transition metals was used as the anode active material, carbon nanotubes were used as the conductive material, and polyvinylidene fluoride (PVDF) was used as the binder. An anode active material slurry was prepared by mixing 96.5 parts by weight of the anode active material, 1.5 parts by weight of the conductive material, and 1.5 parts by weight of the binder. The prepared slurry was coated onto an aluminum current collector and dried to prepare the anode. Additionally, a polyethylene (PE) separator with a thickness of 15 μm was prepared, and the anode was 3×5 cm 2 , the cathode is 3.2×5.2 cm 2 , and the separator is 4×6 cm 2 Each was stamped out by size.

[0089] A lithium secondary battery in the form of a bicell was manufactured by positioning the prepared positive and negative electrodes facing each other, interposing a separator between them, and charging with an electrolyte. At this time, each monocell was manufactured by dissolving LiFSI at a concentration of 1.0 M in an organic solvent composed of ethylene carbonate / ethyl methyl carbonate (the mixed volume ratio of EC / EMC was 3 / 7) as the electrolyte.

[0090] 2) Charging was performed at 0.5C intervals from 0.5C to 4C based on the fabricated monocell. Based on the charging profile for each rate speed, the limit charging capacity for each rate speed was defined.

[0091] 3) FIG. 2 illustrates the measurement results of the limit SOC for each C-rate of a cell with a cathode according to an embodiment of the present invention. As a result, it can be seen that the limit capacity for Li dendrite formation increased in the cathode with added ceramic when charged at a rate limit of 0.5 C or higher, and was maximized as the rate limit increased.

[0092]

[0093] Experimental Example 3: Zeta Potential Measurement

[0094] The zeta potential of MgO in Example 1 and Al2O3 in Example 2 was measured, respectively.

[0095] The zeta potential measurements of each ceramic particle are shown in Table 1 below. Since the + / - sign indicates directionality when measuring zeta potential, the magnitude of the values ​​was compared based on the absolute value.

[0096] MgO (Example 1) Al2O3 (Example 2) Zeta potential 22 mV 30 mV

[0097] Referring to Table 1, when the non-reducing particles of Examples 1 and 2 of the present invention are added, the absolute value of the zeta potential can be confirmed to be 20 mV or higher and 30 mV or higher, indicating high non-reducing properties and surface potential, and thus excellent rapid charging characteristics can be achieved as described above.

[0098]

[0099] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

1. Cathode current collector; and A negative active material layer formed on at least one surface of the above negative current collector; comprising The above-mentioned negative electrode active material layer comprises negative electrode active material particles and electrode additive particles, and the negative electrode active material particles and electrode additive particles are dispersed on the negative electrode active material layer. The above electrode additive particles comprise non-reducing ceramic particles, and the non-reducing ceramic particles comprise one or more of boehmite, magnesium oxide (MgO), and alumina (Al2O3), a negative electrode for a secondary battery.

2. In Paragraph 1, The above electrode additive particles increase the free lithium ion concentration on the surface of the negative electrode active material, a negative electrode for a secondary battery.

3. In Paragraph 1, A negative electrode for a secondary battery, wherein the above electrode additive particles are included in an amount of 0.5 to 3 weight percent based on the total weight of the electrode.

4. In Paragraph 1, The above electrode additive particles have an average diameter in the range of 100 to 300 nm, for a negative electrode for a secondary battery.

5. In Paragraph 1, The above electrode active material particles have an average diameter in the range of 1 to 20 μm, a negative electrode for a secondary battery.

6. In Paragraph 1, The above electrode additive particles are a negative electrode for a secondary battery having an absolute value of zeta potential of 20 mV or more.

7. In Paragraph 6, The above electrode additive particles are a negative electrode for a secondary battery having an absolute value of zeta potential of 30 mV or more.

8. In Paragraph 1, The above electrode active material particles comprise one or more materials selected from the group consisting of carbonaceous materials, metallic compounds, and metal oxides, for a negative electrode for a secondary battery.

9. In Paragraph 1, A negative electrode for a secondary battery, wherein the outer surface of the above electrode active material particles, in whole or at least part thereof, is coated with the above electrode additive particles.

10. In Paragraph 1, The above electrode for a secondary battery is a negative electrode for a secondary battery having a charge / discharge capacity of 30 mAh / g or less at 0.01-1.5V relative to Li.

11. Anode; A secondary battery comprising: a negative electrode for a secondary battery according to any one of claims 1 to 10; and an electrolyte layer interposed between the positive electrode and the negative electrode.

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