Electrode for anode-free battery having oxide-based solid electrolyte protective layer and lithium secondary battery comprising same

Abstract

The present invention relates to an electrode and a secondary battery, capable of ensuring the stability of lithium deposition / dissolution and preventing lithium dendrite formation and internal short circuits in the lithium secondary battery. The electrode for an anode-free battery comprises: an anode current collector; and an anode protective layer disposed on the anode current collector, wherein the anode protective layer may contain oxide-based solid electrolyte particles.

Description

Electrode for a non-anode battery having an oxide-based solid electrolyte protective layer and lithium secondary battery including the same

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

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0163656, filed November 22, 2023, and Korean Patent Application No. 10-2024-0161137, filed November 13, 2024, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to an electrode for a non-anode battery capable of improving the stability of lithium deposition / deposition behavior, etc., and a lithium secondary battery including the same.

[0004] Recently, as the application areas of lithium secondary batteries have rapidly expanded to include not only power supply for electronic devices such as electric, electronic, communication, and computer devices, but also power storage for large-area devices such as automobiles and power storage devices, the demand for lithium secondary batteries with high capacity, high output, long life, and high stability is increasing.

[0005] Lithium metal secondary batteries utilize lithium metal (Li-metal) as the anode active material. Compared to conventional batteries using graphite or lithium alloy anodes, they theoretically offer significantly higher energy density and capacity. Therefore, research and development are ongoing to apply these lithium metal secondary batteries to batteries requiring high energy densities.

[0006] However, lithium metal secondary batteries have a problem in that the volume of the anode changes significantly during the charging / discharging process due to the characteristics of lithium metal, the anode active material. Furthermore, the lithium generated during charging can grow into needle-like structures, forming lithium dendrites. If this lithium dendrite growth continues, it can penetrate the separator and cause a short circuit in the cell, which can lead to serious problems with battery performance or even safety issues such as fire.

[0007] Meanwhile, in the case of lithium metal used as the anode material in the lithium metal secondary battery, irreversible reactions can continuously occur during the charge / discharge process due to its high reactivity with the electrolyte. The surface film formed through this irreversible reaction not only presents the problem of collapse due to the large volume change during charge / discharge, causing additional irreversible reactions, but also, due to this continuous irreversible reaction, the Coulombic efficiency of the cell can be lowered, and the overall performance of the cell can be degraded.

[0008] Due to the major disadvantages of these lithium metal anodes, research and attempts have been continuously conducted to form a cathode protective layer on the surface of the lithium metal anode by applying various materials and methods to suppress problems caused by continuous irreversible reactions on the surface of the lithium metal or disadvantages caused by lithium dendrite growth.

[0009] Accordingly, the present invention provides an electrode for a non-anode battery that can solve the problem of sudden death caused by lithium dendrite growth and internal short circuit due to uneven ion distribution at the copper collector interface. More specifically, it aims to secure the stability of lithium deposition / desorption behavior and delay the decomposition of solvents and salts, thereby resolving the lifespan problem caused by lithium dendrite formation and internal short circuit.

[0010] Hereinafter, an electrolyte composition for a lithium metal battery according to a specific embodiment of the invention will be described.

[0011] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0012] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0013] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0014] In addition, in this specification, the term “anode-free battery” may refer to a secondary battery in which, before charging and discharging, for example, immediately after manufacturing, there is no separate anode active material layer, such as a lithium metal layer, a lithium alloy layer, or other carbon-containing layer, on the anode current collector, which includes a conductive metal layer such as copper and a metal oxide layer having a large work function. Accordingly, the “anode-free battery” may be defined as one in which, before charging and discharging, the anode is formed of the anode current collector and does not include a separate anode active material layer or lithium metal layer on the anode current collector. However, it should be understood that, in addition to the anode active material layer or lithium metal layer, addition of a separate insulating layer or other thin film that does not participate in the movement of lithium ions and / or electrons during charging and discharging is not limited.

[0015] Additionally, the term “non-cathode battery” above cannot be interpreted as limiting the presence of a lithium-containing cathode active material, or limiting the presence of a lithium metal layer or lithium-containing compound grown on the cathode current collector as a result of charge and discharge operations.

[0016]

[0017] Electrode for anode-free batteries

[0018] According to one embodiment of the present invention, an electrode for a non-anode battery is provided, comprising: a negative electrode current collector; and a negative electrode protective layer positioned on the negative electrode current collector; wherein the negative electrode protective layer includes oxide-based solid electrolyte particles, and the oxide-based solid electrolyte particles have an average diameter of 0.02 to 10 ㎛ and a particle size distribution span of < 1. The electrode for a non-anode battery can secure stability in lithium deposition / deposition behavior by applying a negative electrode protective layer positioned on the negative electrode current collector and including oxide-based solid electrolyte particles, thereby controlling the distribution of lithium ions and the structure of the electrolyte at the interface of the metal current collector during charge / discharge.

[0019] In an exemplary embodiment, the negative electrode current collector may be, but is not limited to, 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, as well as copper (Cu) or stainless steel surface-treated with carbon (C), nickel (Ni), titanium (Ti), or silver (Ag). The negative electrode current collector may have a form such as a foil, a film, a sheet, a punched form, a porous body, or a foam.

[0020] In an exemplary embodiment, the cathode protective layer may further include a conductive material. The conductive material may enhance the active surface area of ​​lithium nuclides. Specifically, the conductive material may include one or more selected from the group consisting of carbon powder such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black; graphite powder such as natural graphite, artificial graphite, or graphite with a highly developed crystal structure; and conductive nanomaterials such as graphene, carbon nanofibers, or carbon nanotubes. For example, the conductive material may include carbon black having a spherical shape or graphene having a plate shape.

[0021] In an exemplary embodiment, the oxide-based solid electrolyte particles may have an average diameter of 0.02 to 10 μm and a particle size distribution span < 1. For example, the oxide-based solid electrolyte particles may have a range of 0.05 μm or more, 0.1 μm or more, 0.2 μm or more, and 5.0 μm or less, 3.0 μm or less, 1.0 μm or less, 0.5 μm or less, 0.4 μm or less, or 0.3 μm or less. Preferably, the particles may have an average diameter range of 0.1 μm to 1.0 μm, 0.1 to 0.5 μm, or 0.2 to 0.4 μm. Meanwhile, if the particle size distribution span < 1 is out of the range, the cathode protective layer may not be properly applied.

[0022] Specifically, the oxide-based solid electrolyte particles may have a uniform particle size distribution with a specific average diameter and a span of 1 or less. As a result of experiments by the inventors of the present invention, when oxide-based solid electrolyte particles satisfying a specific particle size distribution are included in the electrode protective layer, the metal current collector interface ion distribution can be made uniform.

[0023] In addition, the oxide-based solid electrolyte particles may exhibit a single peak in the 0.1 to 1.0 μm range through particle size distribution (PSD) analysis. If the oxide-based solid electrolyte particles are not sufficiently dispersed and aggregate, they may exhibit a bimodal distribution with double peaks, which may result in cracks or performance imbalances during drying after slurry application.

[0024] In an exemplary embodiment, the oxide-based solid electrolyte may have a sample dispersion of 0.04 or less, as expressed by the following mathematical formula 1, as determined through EDS analysis.

[0025] [Mathematical Formula 1]

[0026]

[0027] Here, S 2 is the sample variance, y is the variable, is the sample mean, n is the sample size, SS is the sum of squared deviations, and df is the degrees of freedom.

[0028] For example, the sample dispersion may be 0.04 or less, or 0.03 or less, and if the sample dispersion exceeds 0.04, uniform dispersion of the oxide-based solid electrolyte may not be ensured, and thus stability of lithium deposition / deposition behavior, etc. may not be ensured.

[0029] Specifically, the sample variance can be calculated by extracting pixel information of an EDS Ti and / or P element mapping image, dividing the extracted pixel information into n uniform grids, and setting each sample as a sample using the above mathematical formula 1. The sample variance value represents the distribution of the dispersion of Ti and P between each grid, and a smaller sample variance value means that the Ti and P elements are distributed uniformly throughout the entire grid. Therefore, a smaller sample variance value indicates that the oxide-based solid electrolyte (LATP) within the electrode protective layer is distributed more uniformly.

[0030] Meanwhile, the above sample dispersion can be obtained by analyzing the distribution of the oxide-based solid electrolyte (LATP) within the electrode based on the mapping image of the Ti and P elements of the oxide-based solid electrolyte LATP among the SEM and EDS analysis results of the electrode cross-section, and specifically, it was converted and extracted in the form of an Excel file based on the pixel information of the EDS Ti and P element mapping image. The extracted data can be divided into a total of 1150 grids of 50 X 23 and set as a sample, and the sample dispersion of the Ti and P elements can be calculated.

[0031] In an exemplary embodiment, the oxide-based solid electrolyte may be any solid electrolyte having a lithium ion source including lithium in its structure and having the form of a lithium metal oxide or lithium metal phosphate.

[0032] Specific examples thereof include at least one lithium metal oxide or lithium metal phosphate selected from a Nasicon-type solid electrolyte, a Lisicon-type solid electrolyte, a Garnet-type solid electrolyte, a Perovskite-type solid electrolyte, and a LiPON-type solid electrolyte, and more specific examples thereof include at least one selected from the group consisting of a LAGP (lithium aluminum germanium phosphate) compound, an LLZO (lithium lanthanum zirconium oxide) compound, a LATP (lithium aluminum titanium phosphate) compound, an LLZTO (lithium lanthanum zirconium tantalum oxide) compound, an LLTO (lithium lanthanum titanium oxide) compound, a LSTP (lithium silicon titanium phosphate) compound, and a LGPO (lithium germanium phosphate) compound.

[0033] Among these, in terms of uniformly distributing lithium ions at the collector interface, a NASICON-type solid electrolyte such as the LAGP-type compound or LATP-type compound can be appropriately used.

[0034] In an exemplary embodiment, the negative electrode protective layer may further include a binder. The binder may be a component that assists in the bonding of oxide-based solid electrolyte particles and the like and in the bonding to a current collector. Typically, the binder is a component that assists in the bonding of the active material and the conductive material and the like in the negative electrode protective layer and in the bonding to a current collector, and may be typically added in an amount of 1 to 30 wt% based on the total weight of the solid content in the negative electrode slurry. It is added in an amount of 1 to 50 wt%, more specifically 3 to 15 wt%, based on the total weight of the solid content in the negative electrode slurry. If the binder is less than 1 wt%, the adhesive strength between the electrode active material and the current collector may become insufficient, and if it exceeds 50 wt%, the adhesive strength may be improved, but the content of the electrode active material may decrease, which may lower the battery capacity.

[0035] Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluoroelastomer, and various copolymers.

[0036] In an exemplary embodiment, the cathode protective layer may have a thickness of 1 to 10 μm. If the thickness range exceeds 10 μm, it may be advantageous in delaying internal short circuits due to lithium resin phases, but may deteriorate battery performance by maximizing resistance in terms of ion conduction.

[0037] In an exemplary embodiment, the oxide-based solid electrolyte particles may be included in an amount of 50 to 95 wt% based on the total weight of the cathode protective layer. When the oxide-based solid electrolyte particles are included in the above-described range, the stability of lithium electrodeposition / deposition behavior, etc. may be improved. In particular, when the amount is less than 50 wt%, the effect of adding the oxide-based solid electrolyte may be minimal.

[0038] Meanwhile, a method for manufacturing an electrode for a non-anode battery is provided, comprising the steps of preparing a solid electrolyte dispersion by mixing and dispersing an oxide-based solid electrolyte and a solvent; and forming an electrode protective layer by applying the solid electrolyte dispersion onto an electrode current collector.

[0039] In an exemplary embodiment, the solid electrolyte dispersion preparation step may be performed using a bead-milling method. By pre-dispersing the oxide-based solid electrolyte and the solvent prior to forming the electrode protective layer, the oxide-based solid electrolyte particles can be uniformly distributed within the electrode protective layer.

[0040]

[0041] lithium secondary battery

[0042] According to another embodiment of the present invention, a lithium secondary battery is provided, comprising: a positive electrode; a negative electrode; and an electrolyte including a lithium salt and a non-aqueous organic solvent; and including the above-described electrode for a non-anode battery as a negative electrode. The lithium secondary battery according to another embodiment of the present invention applies an electrode protective layer including oxide-based solid electrolyte particles and a conductive material to control the distribution of lithium ions and the structure of the electrolyte at the interface of a copper current collector during charge / discharge, thereby ensuring the stability of the deposition / desorption behavior of lithium and delaying the decomposition of solvents and salts, thereby solving the lifespan problem caused by lithium dendrite formation and internal short circuit.

[0043] In an exemplary embodiment, the negative electrode may not include a negative electrode active material layer, but may only include a negative electrode current collector. In such a negative electrode, lithium ions moved from the positive electrode during the charge and discharge process may be deposited on the negative electrode current collector to form a lithium metal layer, and this lithium metal layer may function as a negative electrode active material.

[0044] Meanwhile, a positive electrode for a lithium secondary battery according to an exemplary embodiment can be manufactured by, for example, mixing and dispersing the positive electrode active material, oxide-based solid electrolyte, binder, and conductive agent in a dispersion medium (solvent) to make a slurry, applying the slurry on a metal current collector, and then drying and rolling. At this time, the dispersion medium may be NMP (N-methyl-2-pyrrolidone), DMF (Dimethyl formamide), DMSO (Dimethyl sulfoxide), ethanol, isopropanol, water, and mixtures thereof, but is not necessarily limited thereto.

[0045] In an exemplary embodiment, the electrolyte may further include a separator interposed between the positive and negative electrodes, or the electrolyte may have the form of an electrolyte membrane or electrolyte film containing the lithium salt and a non-aqueous organic solvent within a polymer matrix, and may be interposed between the positive and negative electrodes.

[0046] The lithium secondary battery of another embodiment described above comprises an electrolyte comprising a lithium salt and a non-aqueous organic solvent. This electrolyte acts as a transport medium for lithium ions between the positive and negative electrodes. These lithium ions exist in the electrolyte in a solvated state, while at the interface between the electrolyte and the electrode, they can be desolvated and inserted into the electrode active material.

[0047] The lithium salt included in the above electrolyte is used as a medium for transferring ions within a lithium secondary battery. The lithium salt is, for example, Li as a cation. + Including, F - , Cl- , Br - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , B 10 Cl 10 - , AlCl4 - , AlO2 - , PF6 - , CF3SO3 - , CH3CO2 - , CF3CO2 - , AsF6 - , SbF6 - , CH3SO3 - , (CF3CF2SO2)2N - , (CF3SO2)2N - , (FSO2)2N - , BF2C2O4 - , BC4O8 - , PF4C2O4 - , PF2C4O8 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , C4F9SO3 - , CF3CF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , CF3(CF2)7SO3 - and SCN - It may contain an anion selected from the group consisting of. For example, the lithium salt may be LiCl, LiBr, LiI, LiBF4, LiClO4, LiB 10 Cl 10, LiAlCl4, LiAlO2, LiPF6, LiCF3SO3, LiCH3CO2, LiCF3CO2, LiAsF6, LiSbF6, LiCH3SO3, LiFSI (lithium bis(fluorosulfonyl) imide, LiN(SO2F)2), LiBETI (lithium bis(perfluoroethanesulfonyl) imide, LiN(SO2CF2CF3)2) and LiTFSI (lithium bis(trifluoromethanesulfonyl) imide, LiN(SO2CF3)2).

[0048] The concentration of the above lithium salt can be appropriately changed within a commonly usable range, and can be included in the electrolyte at a concentration of 0.5 M to 6 M, or a concentration of 1 M to 5 M.

[0049] In a more specific embodiment, the electrolyte may include a lithium salt in a relatively low concentration of 0.5 M or more and less than 2 M, or 0.7 M to 1.5 M. Even in this case, since the desolvation of lithium ions is accelerated by the action of the electrode of the above-described embodiment, the lithium secondary battery of another embodiment may exhibit improved output characteristics. As a result, problems such as increased electrolyte viscosity, decreased fluidity, and decreased ion conductivity of the electrolyte and battery output at low temperatures due to the application of an electrolyte composition including a high concentration of lithium salt can be solved, and excellent low-temperature characteristics of the lithium secondary battery can be achieved at the same time.

[0050] Meanwhile, by applying a lithium-ion battery electrode according to one embodiment, lithium ion conductivity can be improved and resistance can be reduced even at low temperatures. This can reduce the deterioration of low-temperature output characteristics due to high-concentration lithium salts, etc.

[0051] Meanwhile, the type of non-aqueous organic solvent that can be included in the electrolyte is not particularly limited, and any organic solvent previously known to be applicable to electrolytes of lithium ion batteries, etc., can be used. Examples of such organic solvents include at least one selected from the group consisting of carbonate solvents, ether solvents, nitrile solvents, phosphate solvents, and sulfone solvents.

[0052] More specifically, as the carbonate solvent, 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 can be used, and as the phosphate solvent, trimethyl phosphate, triethyl phosphate or 2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphosphorane 2-oxide can be used.

[0053] In addition, as the ether solvent, dibutyl ether, tetraglyme, diglyme, dimethoxy ethane, or tetrahydrofuran derivatives such as 2-methyl tetrahydrofuran can be used, and as the nitrile solvent, succinonitrile, adiponitrile, sebaconitrile, acetonitrile, or propionitrile can be used. In addition, as the sulfone solvent, dimethyl sulfone, ethylmethyl sulfone, or sulforane can be used.

[0054] Meanwhile, the electrolyte may further include, in addition to the lithium salt and the non-aqueous organic solvent described above, a diluent that exhibits a solubility in the lithium salt that is at least 10 times lower than that of the non-aqueous organic solvent. The diluent may be an organic solvent that is miscible with the non-aqueous organic solvent while exhibiting substantially no solubility in the lithium salt, for example, an ether solvent having a fluorine-substituted alkyl group, and more specifically, may include at least one selected from the group consisting of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (TFTFE), methoxynonafluorobutane (MOFB), and ethoxynonafluorobutane (EOFB).

[0055] When such a diluent is further included, a high-concentration lithium salt may be locally present in the non-aqueous organic solvent within the electrolyte, and substantially no lithium salt may be present within the diluent. In this way, since a high-concentration lithium salt is locally present in a solvated form within the electrolyte, the output characteristics of the lithium secondary battery can be further improved, while the increase in viscosity and decrease in fluidity of the electrolyte can be reduced. In addition, when the electrode of one embodiment is applied together with such a high-concentration salt electrolyte, lithium ion conductivity can be improved and resistance can be reduced even at low temperatures, thereby reducing the deterioration of low-temperature output characteristics due to high-concentration lithium salt, etc.

[0056] The amount of the diluent used can be adjusted depending on the type of non-aqueous organic solvent and lithium salt, or the overall concentration of the lithium salt, and for example, the diluent: non-aqueous organic solvent can be included in the electrolyte in a molar ratio of 1:0.2 to 1:5, or 1:0.5 to 1:2.

[0057] Meanwhile, the lithium secondary battery of another embodiment described above may further include a porous separator interposed between the positive electrode and the negative electrode.

[0058] These porous membranes can be made of olefin polymers such as polyethylene and polypropylene, glass fibers, etc. in the form of sheets, multi-membranes, microporous films, woven fabrics, and non-woven fabrics, but are not necessarily limited thereto. However, it may be preferable to use porous polyethylene or porous glass fiber non-woven fabric (glass filter) as the membrane, and it may be more preferable to use porous glass filter (glass fiber non-woven fabric) as the membrane. The membrane may be an insulating thin film having high ion permeability and mechanical strength, and the pore diameter of the membrane may generally be in the range of 0.01 to 10 ㎛, and the thickness may generally be in the range of 5 to 300 ㎛, but is not limited thereto.

[0059] In addition, in another example of the lithium secondary battery, the separator may not be interposed, and the electrolyte described above may be interposed between the positive and negative electrodes in the form of an electrolyte membrane or electrolyte film. In this case, the electrolyte membrane or electrolyte film may be in the form of a polymer matrix containing the lithium salt and a non-aqueous organic solvent described above, and a well-known polymer-based solid electrolyte or the like may be used as the polymer matrix. In this case, the lithium secondary battery of the other embodiment may be a semi-solid battery that uses a liquid electrolyte and a solid electrolyte in combination.

[0060] Meanwhile, the lithium secondary battery of the above-described other embodiment can be manufactured according to a conventional method in the art. For example, the electrode assembly including the positive electrode, negative electrode, and separator (or electrolyte membrane) can be manufactured by a method in which the electrode assembly is housed in a case and the electrolyte described above is injected and impregnated.

[0061] These lithium secondary batteries can be applied to battery cells used as power sources for small devices, and are particularly suitable for use as unit cells in battery modules that serve as power sources for medium- to large-sized devices.

[0062] The electrode for a non-anode battery of the present invention is positioned on an anode current collector, and applies an anode protective layer including oxide-based solid electrolyte particles to control the distribution of lithium ions and the structure of the electrolyte at the interface of the metal current collector during charge / discharge, thereby ensuring stability of lithium deposition / deposition behavior.

[0063] Additionally, it can solve life problems caused by lithium dendrite formation and internal short circuit by delaying the decomposition of solvents and salts.

[0064] Figure 1-4 shows the voltage change according to areal capacity in a battery using the electrode according to Example 1-2 and Comparative Example 1-2.

[0065] Figure 5 shows the change in polarization level according to cycle in a battery using an electrode according to Example 1-2 and Comparative Example 1-2.

[0066] Figure 6 shows the coulombic efficiency according to cycle in a battery using the electrode according to Example 1-2 and Comparative Example 1-2.

[0067] Figure 7 shows the results of measuring the particle size distribution (PSD) of the oxide-based solid electrolyte LATP in the electrode according to Example 1.

[0068] Figure 8 shows the results of measuring the particle size distribution (PSD) of the oxide-based solid electrolyte LATP in the electrode according to Comparative Example 2.

[0069] Figure 9 shows the results of EDS analysis of an electrode according to Example 1.

[0070] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0071]

[0072] Example 1: LATP protective layer electrode

[0073] D50: LiAl of 300 nm 0.3 Ti 1.7 (PO4)3 oxide solid electrolyte (LATP) 10 g, PVdF binder (PVdF:LATP weight ratio 10:90), and NMP 90 g were mixed, a bead mill was added to the mixture, and dispersion treatment was performed for 40 minutes using a spike mill to prepare a solid electrolyte nanoparticle dispersion. Then, the solid electrolyte nanoparticle dispersion was sprayed on a Cu current collector and dried to form a protective layer with a thickness of 8 μm, thereby preparing an electrode for a non-anode battery having a LATP protective layer.

[0074]

[0075] Example 2: LATP & CNT protective layer electrode

[0076] D50: LiAl of 300 nm 0.3 Ti 1.7 An electrode for a non-anode battery having a LATP & CNT protective layer was manufactured in the same manner as in Example 1, except that 50 g of a (PO4)3 oxide-based solid electrolyte (LATP), a PVdF binder (PVdF:LATP weight ratio of 10:90), 50 g of CNT, and 50 g of NMP were mixed.

[0077]

[0078] Comparative Example 1: Bare Electrode

[0079] A Cu collector (SK Nexillions, 8㎛) was used.

[0080]

[0081] Comparative Example 2: Span=3.883 electrode

[0082] An electrode for a cathode-free battery having a LATP protective layer was manufactured in the same manner as in Example 1, except that dispersion treatment for 40 minutes using a spike mill was not performed. Meanwhile, it was confirmed that cracks formed on the protective layer of the manufactured electrode during the drying process after application of the cathode protective layer.

[0083]

[0084] Experimental Example 1: Particle Size Distribution (PSD) Measurement Results

[0085] To determine the particle size distribution of the oxide-based solid electrolyte LATP in the electrodes of Example 1 and Comparative Example 2, a particle size analyzer (Malvern Mastersizer) was used. The resulting graphs are shown in Figs. 7 and 8. Referring to Fig. 7, a single peak was observed around 0.2 to 0.3 μm. Thus, it was confirmed that the average diameter of Example 1 was 0.02 - 10 μm and the particle size distribution span was < 1.

[0086] On the other hand, referring to Fig. 8, in the case of Comparative Example 2, a double peak was observed, and the measurements were D10: 0.454 um, D50: 0.827 um, D90: 3.66 um, D99: 5.18 um, and D100: 5.91 um, confirming that the particle size distribution span was 3.883, and span > 1.

[0087]

[0088] Experimental Example 2: EDS Analysis

[0089] Example 1 Based on the mapping images of O elements, Ti elements, and P elements of the oxide-based solid electrolyte LATP among the SEM and EDS analysis results of the electrode cross-section, the distribution of the oxide-based solid electrolyte (LATP) within the electrode was analyzed, and the results are shown in Fig. 9.

[0090] First, based on the pixel information of the EDS O, Ti, P element mapping image, it was converted into an Excel file and extracted. The extracted data was divided into 1150 grids (50 X 23) and set as samples, and the sample variance of O, Ti, and P elements was calculated. The specific sample variance was obtained using the following mathematical equation 1.

[0091] [Mathematical Formula 1]

[0092]

[0093] Here, S2 is the sample variance, y is the variable, is the sample mean, n is the sample size, SS is the sum of squared deviations, and df is the degrees of freedom.

[0094] As a result, Example 1 can be confirmed to have a sample variance of 0.04 or less.

[0095]

[0096] Experimental Example 3: Lithium Electrodeposition Behavior

[0097] Coin cells were manufactured using the electrodes of Example 1-2 and Comparative Example 1-2. Specifically, a Cu anode (Cu coated with LATP can also be used), a separator, and a gasket were sequentially layered on the bottom of the coin cell, followed by application of an electrolyte. Next, a lithium metal anode, a 1 mm thick spacer, and a spring were sequentially placed as the cathode, closed with a cap, and sealed by applying a certain pressure.

[0098]

[0099] 1) Assembled coin cell at 0.5 mA cm -2 By applying a current density of 1 mAh cm -2 The electrodeposition was performed on Cu to have a capacity per area of ​​, and when stripping the electrodeposited lithium, a 1 V cut-off was performed at the same current density.

[0100] Figure 1-4 shows the voltage change according to areal capacity in batteries using electrodes according to Example 1-2 and Comparative Example 1-2. In the experiment, it was expected that there would be a decrease in Li deposition overpotential when a space charge region was formed, but it was confirmed that the initial nucleation overpotential increased with the introduction of the electrode protective layer. This is expected to be due to the influence of the initial bulk diffusion.

[0101]

[0102] 2) Referring to Fig. 5, the overvoltage between the charge / discharge curves was measured in the intermediate flat area excluding the initial and final stages under the experimental conditions of Figs. 1-4 above.

[0103] Figure 5 shows the change in polarization level according to cycle in the batteries using the electrodes according to Examples 1-2 and Comparative Example 1. As a result, it was confirmed that the efficiency was improved due to the increase in the deposition / desorption rate when the electrode protection layer was introduced, and also the polarization level between the deposition and desorption was lowered. In particular, it was confirmed that Comparative Example 2, which had a span > 1 range, had the highest polarization level. Through this, it was confirmed that the life characteristics were improved through the electrode protection layer, and in particular, the capacity realization rate could be improved.

[0104]

[0105] 3) Next, the charge-discharge efficiency was measured. In this experiment, the charge-discharge efficiency is the ratio of the deposition amount to the desorption amount, and can be expressed by the following formula.

[0106] [Mathematical Formula 1]

[0107] Charge / discharge efficiency (%) =

[0108] Figure 6 shows the lithium deposition / deposition efficiency according to cycles in batteries using electrodes according to Example 1-2 and Comparative Example 1-2. As a result, it was confirmed that up to 95% of the deposition amount could be desorbed due to the introduction of a protective layer, and that the efficiency was improved by approximately 10% compared to Comparative Example 1.

Claims

1. Negative current collector; and A cathode protective layer positioned on the above cathode current collector; The above cathode protective layer comprises oxide-based solid electrolyte particles, An electrode for a non-anode battery, wherein the above oxide-based solid electrolyte particles have an average diameter of 0.02 to 10 ㎛ and a particle size distribution span of < 1.

2. In paragraph 1, The above cathode protective layer further includes a conductive material, An electrode for a non-anode battery, wherein the above-mentioned conductive material is at least one selected from the group consisting of carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, natural graphite, artificial graphite, graphite, carbon nanofibers, and carbon nanotubes.

3. In paragraph 1, An electrode for a lithium secondary battery, wherein the oxide-based solid electrolyte particles exhibit a single peak in the range of 0.1 to 1.0 μm as determined by particle size distribution (PSD) analysis.

4. In paragraph 1, The above oxide-based solid electrolyte is an electrode for a lithium secondary battery, having a sample dispersion of 0.04 or less, as expressed by the following mathematical formula 1, as determined through EDS analysis. [Mathematical formula 1] Here, S 2 is the sample variance, y is the variable, is the mean of the sample, n is the sample size, SS is the sum of squares of deviations, and df is the degrees of freedom.

5. In paragraph 1, An electrode for a non-anode battery, wherein the oxide-based solid electrolyte comprises at least one selected from the group consisting of a LAGP (lithium aluminum germanium phosphate)-based compound, an LLZO (lithium lanthanum zirconium oxide)-based compound, a LATP (lithium aluminum titanium phosphate)-based compound, an LLZTO (lithium lanthanum zirconium tantalum oxide)-based compound, an LLTO (lithium lanthanum titanium oxide)-based compound, a LSTP (lithium silicon titanium phosphate)-based compound, and a LGPO (lithium germanium phosphate)-based compound.

6. In paragraph 1, An electrode for a cathode-free battery, wherein the cathode protective layer has a thickness of 1 to 20 ㎛.

7. In paragraph 1, An electrode for a cathode-free battery, wherein the oxide-based solid electrolyte particles are contained in an amount of 50 to 95 wt% based on the total weight of the cathode protective layer.

8. Containing a positive electrode; a negative electrode; and an electrolyte including a lithium salt and a non-aqueous organic solvent; A lithium secondary battery comprising an electrode for a non-anode battery according to any one of claims 1 to 7 as a negative electrode.

9. In paragraph 8, The above lithium salts are LiCl, LiBr, LiI, LiBF 4 , LiClO 4 , LiB 10 Cl 10 , LiAlCl 4 , LiAlO 2 , LiPF 6 , LiCF 3 SO 3 , LiCH 3 CO 2 , LiCF 3 CO 2 , LiAsF 6 , LiSbF 6 , LiCH 3 SO 3 , LiFSI (Lithium bis(fluorosulfonyl) imide, LiN(SO 2 F) 2 ), LiBETI (lithium bis(perfluoroethanesulfonyl) imide, LiN(SO 2 CF 2 CF 3 ) 2 and LiTFSI (lithium bis(trifluoromethanesulfonyl)imide, LiN(SO 2 CF 3 ) 2 A lithium secondary battery comprising at least one selected from the group consisting of:

10. In paragraph 8, or further comprising a separator interposed between the positive and negative electrodes, A lithium secondary battery, wherein the electrolyte has a form of an electrolyte membrane or electrolyte film containing the lithium salt and a non-aqueous organic solvent within a polymer matrix and is interposed between the positive electrode and the negative electrode.

Images