Negative electrode for electrochemical device, and secondary battery comprising negative electrode

Abstract

A negative electrode, according to the present invention, comprises a protective layer formed on the surface of a negative electrode active material layer, thereby suppressing growth of lithium dendrites, and porous particles improve electrolyte wettability of the protective layer, thereby improving ionic conductivity. In addition, by means of a single ion-conductive functional group bonded to porous particles, uniform ion conduction is induced across the entire surface of the protective layer, thereby preventing localized electrodeposition of lithium leading to formation of dendrites. Moreover, when such a negative electrode is applied to a lithium-sulfur secondary battery, long-term cycling performance and cycle life characteristics can be improved.

Description

A cathode for an electrochemical device and a secondary battery including said cathode

[0001] This application claims priority based on Korean Patent Application No. 10-2024-0175892 filed on November 29, 2024. The present invention relates to a negative electrode for an electrochemical device and a battery including the same. More specifically, it relates to a negative electrode for a lithium-sulfur battery.

[0002]

[0003] As the application range of lithium-ion batteries expands beyond portable electronic devices to include electric vehicles (EVs) and energy storage systems (ESS), the demand for high-capacity, high-energy-density, and long-life lithium-ion batteries is increasing.

[0004] Among various lithium secondary batteries, the lithium-sulfur battery is a battery system that uses a sulfur compound containing sulfur-sulfur (SS) bonds as the positive electrode active material, and lithium metal, carbon-based materials capable of intercalating / deintercalating lithium ions, or silicon or tin that forms an alloy with lithium metal as the negative electrode active material.

[0005] Lithium-sulfur batteries have the advantages that sulfur, the main material of the cathode active material, has a low atomic weight and is very abundant, making it easy to supply, inexpensive, non-toxic, and environmentally friendly.

[0006] In addition, in lithium-sulfur batteries, the conversion reaction between lithium ions and sulfur (S8 + 16Li) at the cathode + + 16e -The theoretical specific capacity derived from 8Li2S is 1,675 mAh / g, and when lithium metal is used as the negative electrode, the theoretical energy density is 2,600 Wh / kg. Since the theoretical energy density of lithium-sulfur batteries is much higher than that of other battery systems (Ni-MH battery: 450 Wh / kg, Li-FeS battery: 480 Wh / kg, Li-MnO2 battery: 1,000 Wh / kg, Na-S battery: 800 Wh / kg, lithium-ion battery: 250 Wh / kg), lithium-sulfur batteries are attracting attention among secondary batteries developed so far as they are high-capacity, eco-friendly, and low-cost lithium secondary batteries.

[0007] In addition, in the case of lithium-sulfur batteries, when lithium metal is used as the negative electrode active material, the theoretical specific capacity is very high at 3,860 mAh / g, and the Standard Hydrogen Electrode (SHE) is also very low at -3.045 V, making it possible to realize high-capacity, high-energy-density batteries, so various studies are being conducted on them as next-generation battery systems.

[0008] In lithium-sulfur batteries, the SEI layer formed by the reaction between the electrolyte and the lithium metal has weak mechanical strength, so as charging and discharging progresses, its structure collapses, causing local current density differences and forming lithium dendrites on the lithium metal surface. Furthermore, these formed lithium dendrites cause internal short circuits and dead lithium, which not only increase the physical and chemical instability of the lithium secondary battery but also reduce battery capacity and cycle life. Additionally, the positive electrode active material dissolves in the form of lithium polysulfide (LiPS) and migrates to the negative electrode to form lithium sulfide byproducts, which can lead to loss of the positive electrode active material, negative electrode passivation, and unwanted side reactions.

[0009] Due to the high instability of lithium metal and the problem of lithium dendrite formation, lifespan characteristics are degrading, and active research is being conducted to enable long-term cycle operation of lithium-sulfur batteries to address these issues. However, long-term cycle operation is difficult due to the leaching of polysulfide (PS) from the cathode of lithium-sulfur batteries. In lithium-sulfur batteries, a solid-to-liquid reaction in which the electrode active material leaches out as polysulfide from the cathode occurs during the first discharge (~2.3V), followed by a second discharge (~2.1V) in which the leached lithium polysulfide is re-electrodeposited onto the cathode in a solid state. During this process, side reactions between the anode and the electrolyte lead to the growth of dendrites on the anode and the formation of electrically short-circuited inert lithium (dead lithium), making long-term operation of the battery difficult. This problem is particularly exacerbated when lithium metal or lithium alloys are used as the anode. Accordingly, efforts are needed to prevent electrode degradation caused by lithium polysulfide leached from the electrolyte by forming a protective film on the surfaces of the cathode and anode.

[0010]

[0011] The present invention aims to provide an electrolyte for a lithium-sulfur battery to improve the lifespan characteristics of a lithium-sulfur secondary battery by forming a protective film on the surfaces of the negative electrode and the positive electrode. Additionally, another objective is to provide a lithium-sulfur battery comprising said electrolyte. However, the technical problems that the present invention seeks to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below.

[0012]

[0013] The present invention relates to a cathode for an electrochemical device. In one aspect of the present invention, the cathode comprises a cathode active material layer and a protective layer disposed on the surface of the cathode active material layer, wherein the protective layer comprises porous particles and a polymer matrix in which the porous particles are dispersed, wherein the porous particles comprise a vinyl polymer in which benzene rings are bonded to carbons of a main chain, have a hyper-crosslinked structure, and have one or more moiety A grafted to the main chain, wherein the moiety A is terminally substituted by a single ion-conducting functional group, and the polymer matrix comprises a fluorine-based polymer.

[0014] In the aforementioned aspect, the vinyl polymer comprises one or more units derived from a styrene derivative in the main chain, and the units derived from the styrene derivative may include divinylbenzene, chloromethylstyrene, or both.

[0015] In any one of the aforementioned aspects, the moiety A may be bonded to the benzene ring portion of the main chain.

[0016] In any one of the aforementioned aspects, the single ion-conducting functional group may include that represented by the following chemical formula 1.

[0017]

[0018] [Chemical Formula 1]

[0019]

[0020]

[0021] R in Chemical Formula 1 above 1It comprises fluorine (F), a perfluoroalkyl group having 1 to 6 carbon atoms, a perfluoroalkoxy group having 1 to 6 carbon atoms (C1-C6 perfluoroalkoxy), a fluoroalkyl group, a fluorosubstituted alkyl group, a trifluoromethyl group, or one or more of these, and * indicates a point where the functional group of Formula 1 is bonded to moiety A.

[0022] In any one of the aforementioned aspects, R of Formula 1 1 It may include a perfluoroalkyl group having 1 to 6 carbon atoms, a perfluoroalkoxy group having 1 to 6 carbon atoms (C1-C6 perfluoroalkoxy), a fluoroalkyl group, a fluorosubstituted alkyl group, a trifluoromethyl group, or one or more of these. Additionally, a portion thereof may be substituted with an atom other than fluorine.

[0023] In any one of the aforementioned aspects, the single ion-conducting functional group may include that represented by the following chemical formula 1a.

[0024] [Chemical Formula 1a]

[0025]

[0026] The above * indicates a point where the functional group of the above chemical formula 1 is attached to moiety A.

[0027] In any one of the aforementioned aspects, the moiety A may comprise a structure derived from a vinyl group terminally substituted with a single ion-conducting functional group.

[0028] In any one of the aforementioned aspects, the moiety A may comprise one or more compounds derived from the following chemical formulas 2a to 2h.

[0029] [Chemical Formulas 2a to 2h]

[0030]

[0031]

[0032]

[0033] In any one of the aforementioned aspects, the styrene-based polymer of the hyper-crosslinked structure may include a compound represented by the following chemical formula 3.

[0034]

[0035] [Chemical Formula 3]

[0036]

[0037]

[0038] In the above chemical formula 3, n, m, l, and k are each independently integers greater than or equal to 1, and

[0039] At least two units are benzene rings bonded to each other, or at least one unit is grafted with a polystyrene chain.

[0040] In any one of the aforementioned aspects, the fluorine-based polymer may include polyvinylidene fluoride.

[0041] In any one of the aforementioned aspects, the negative electrode active material layer may comprise lithium metal, an alloy of lithium and a heterogeneous metal, or both.

[0042] In any one of the aforementioned aspects, the heterogeneous metal may include aluminum (Al), magnesium (Mg), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), tin (Sn), or two or more of these.

[0043] In any one of the aforementioned aspects, the protective layer may have a thickness in the range of 0.1 μm to 10 μm.

[0044] In any one of the aforementioned aspects, the protective layer may contain 30 wt% to 95 wt% of a fluorinated polymer relative to 100 wt% of the protective layer.

[0045] In any one of the aforementioned aspects, the protective layer may have a porosity of 20 vol% to 80 vol%.

[0046] In any one of the aforementioned aspects, the porous particle may be composed of a core portion having a porous structure and a shell portion having a brush structure grafted onto the core portion.

[0047] One aspect of the present invention relates to a lithium-sulfur secondary battery, wherein the lithium-sulfur secondary battery comprises a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises sulfur (S8), a sulfur-based compound, or both as a positive active material, and the negative electrode may be according to any one of the aforementioned aspects.

[0048] In any one of the aforementioned aspects, the sulfur (S8) and / or sulfur-based compound may be included in the positive active material in the form of a sulfur-carbon composite combined with a porous carbon material.

[0049] The aforementioned embodiments may each be implemented independently. Alternatively, it goes without saying that two or more of the aforementioned embodiments may be implemented in combination.

[0050]

[0051] The cathode according to the present invention has a protective layer formed on the surface of the cathode active material layer, which can suppress the growth of lithium dendrites, and the ion conductivity is enhanced by improving the electrolyte impregnation of the protective layer through porous particles. In addition, by inducing uniform ion conduction across the entire surface of the protective layer through single ion-conducting functional groups bonded to porous particles, it is possible to prevent the localized electrodeposition of lithium and the formation of dendrites. Furthermore, when such a cathode is applied to a lithium-sulfur secondary battery, long-term operating performance and lifespan characteristics can be improved.

[0052]

[0053] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the aforementioned description; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0054] Figure 1 shows the FT-IR analysis results of the manufacturing results at each step in the manufacture of a protective layer according to the present invention.

[0055] Figure 2 shows the size distribution of f-xPCMS particles of the example.

[0056] FIGS. 3 to 5 show SEM images of the manufacturing results at each step in the manufacture of a protective layer according to the present invention.

[0057] FIGS. 6a to 6g respectively show TEM and SEM images of f-xPCMS according to the present embodiment.

[0058] FIG. 7 is a free standing film prepared to measure ion conductivity for a protective layer according to Examples 1 to 5 and Comparative Example 2.

[0059] Figure 8 shows the results of measuring the ion conductivity of the protective layer according to Examples 1 to 5 and Comparative Example 2.

[0060] Figure 9 is an SEM image of the cathode surface prepared in Example 3. Referring to this, it was confirmed that the protective layer coating was well formed.

[0061] Figure 10 is an SEM image of the cathode surface prepared in Comparative Example 1.

[0062] Figure 11 shows the discharge capacity per cycle under a 0.2C rate condition for the batteries of each example and comparative example.

[0063] Figure 12 shows the discharge capacity per cycle under a 0.5C rate condition for the batteries of each example and comparative example.

[0064] Figure 13 shows a comparison of the cycle characteristics of lithium-sulfur batteries under 0.5 C conditions as confirmed in each example and comparative example.

[0065] Figure 14 shows the FT-IR spectrum of Lithiated Nafion (LN) of Comparative Example 3.

[0066] Figure 15 shows the FT-IR spectrum of xPCMS-g-PPEGMA grafted with xPCMS and PEGMA of Comparative Example 4.

[0067] Figure 16 shows a comparison of the cycle characteristics of lithium-sulfur batteries under 0.2 C conditions as confirmed in each example and comparative example.

[0068]

[0069] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0070] 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.

[0071] Furthermore, throughout the specification, when a part is described as 'include' or 'comprise' a certain component, unless specifically stated otherwise, this means that it does not exclude other components but may include additional components.

[0072] Additionally, terms such as “about,” “substantially,” as used throughout this specification, are used to mean at or near the stated value when inherent manufacturing and material tolerances are presented in the said sense, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which precise or absolute values ​​are mentioned to aid in understanding this invention.

[0073] Throughout this specification, the description of 'A and / or B' means 'A or B or both'.

[0074] In this specification, terms relating to position or direction, such as 'up', 'down', 'left', 'right', 'inside', and 'outside', may indicate directions in the referenced drawings and should not be limited. The words 'inside' and 'outside' each indicate a direction toward or away from the geometric center of the designated device, system, and its components. These terms include the words listed above, their derivatives, and words of similar meaning. Furthermore, it is obvious to those skilled in the art that the above terms are used merely for convenience of explanation and may vary depending on the location of the object or the position of the observer.

[0075] In the present specification, when it is stated that a component is located 'on' another component, this includes not only cases where a component is in contact with another component, but also cases where another component exists between the two components.

[0076] In this specification, the term "composite" refers to a material in which two or more materials are combined to form physically and / or chemically different phases in order to exhibit a more effective function.

[0077] The drawings attached to this specification illustrate preferred embodiments of the present invention and serve to help to better understand the technical concept of the present invention together with the description of the invention above; therefore, the present invention is not to be interpreted as being limited only to the matters described in such drawings. Meanwhile, the shape, size, scale, or ratio of elements in the drawings included in this specification may be exaggerated to emphasize a clearer explanation.

[0078]

[0079] The present invention will be described in detail below. Prior to this, terms or words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe their invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely one preferred embodiment of the present invention and do not represent all aspects of the technical spirit of the present invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0080]

[0081] cathode and protective layer

[0082] The present invention relates to a cathode for an electrochemical device.

[0083] The cathode according to the present invention comprises a cathode active material layer and a protective layer disposed on the surface of the cathode active material layer.

[0084] The above negative electrode active material layer may include lithium metal. In addition to this, or independently, the above negative electrode active material layer may include a lithium alloy. The lithium alloy is an alloy of lithium and a heterogeneous metal, wherein the heterogeneous metal may include aluminum (Al), magnesium (Mg), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), tin (Sn), or two or more of these.

[0085] The above-mentioned negative electrode active material layer is not particularly limited, but may have a thickness in the range of 20㎛ to 100㎛.

[0086] The protective layer comprises porous particles and a polymer matrix in which the porous particles are dispersed.

[0087] In one embodiment of the present invention, the protective layer may have a thickness in the range of about 0.1 μm to 10 μm, preferably 0.1 μm to 6 μm. The thickness of the protective layer may be appropriately controlled within the above range. For example, the protective layer may have a thickness of about 3.2 μm to 6.0 μm. In addition, it is preferable that the protective layer has a porosity in the range of 20 vol% to 80 vol%. The protective layer according to the present invention may have a porosity of 80 vol% or less, 70 vol% or less, 60 vol% or less, 50 vol% or less, 40 vol% or less, or 30 vol% or less. Alternatively, the porosity may be 20 vol% or more, 30 vol% or more, 40 vol% or more, 50 vol% or more, 60 vol% or more, or 70 vol% or more. For example, the porosity may be 20 vol% to 55 vol%. As a more specific example, the above porosity may be 40 vol% to 50 vol%. The above porosity can be appropriately controlled within the above range depending on the content and content ratio of the added component.

[0088]

[0089] porous particles

[0090] In the present invention, the porous particles comprise a vinyl polymer in which a benzene ring is bonded to a carbon of the main chain. The vinyl polymer may have a hyper-crosslinked structure and may have various structural bridges formed between phenyl groups. The structural bridges may be formed between adjacent phenyl groups in the main chain. Meanwhile, the vinyl polymer may have one or more moiety A grafted to the main chain, and moiety A may be terminally substituted by a single ion-conducting functional group.

[0091] In the present invention, the porous particle can be described as being composed of a core portion having a porous structure and a shell portion having a brush structure grafted onto the core portion, wherein the supercrosslinked structure of the main chain forms the core portion, and moiety A grafted onto the main chain forms the brush structure on the surface.

[0092]

[0093] In one embodiment of the present invention, the vinyl polymer may include one or more units derived from styrene and / or styrene derivatives in the main chain. In the present invention, the units derived from styrene derivatives may include divinylbenzene, chloromethylstyrene, or both. In a specific embodiment of the present invention, the divinylbenzene and chloromethylstyrene may be included in a molar ratio of, for example, about 1:30 to 70.

[0094]

[0095] Meanwhile, in the present invention, the moiety A may be bonded to a benzene ring portion of the main chain. The moiety A may be directly bonded to the benzene ring or bonded to a functional group bonded to the benzene ring, but is not particularly limited thereto. In one embodiment of the present invention, the precursor of the vinyl polymer may have a unit derived from chloromethylstyrene, and the moiety A may be bonded through an SI-ATRP reaction with the -CH2Cl of the unit.

[0096]

[0097] In one embodiment of the present invention, the single ion-conducting functional group may include a sulfonimide-based group in which one or more sulfonyl groups (SO2-) are bonded to a nitrogen atom. In a specific embodiment, the sulfonimide-based group may include a lithium salt of a TFSI ((Trifluoromethanesulfonyl)imide) derivative.

[0098] In a specific embodiment, the single ion-conducting functional group may include one represented by the following chemical formula 1.

[0099]

[0100] [Chemical Formula 1]

[0101]

[0102]

[0103] Specifically, the above R 1 It may include fluorine (F), a perfluoroalkyl group having 1 to 6 carbon atoms, a perfluoroalkoxy group having 1 to 6 carbon atoms (C1-C6 perfluoroalkoxy), a fluoroalkyl group, a fluorosubstituted alkyl group, a trifluoromethyl group, or one or more of these. In another embodiment, R 1In the case of a form other than fluorine, a portion thereof may be substituted with atoms other than fluorine. In a more specific embodiment, the single ion-conducting functional group may include that represented by the following chemical formula 1a.

[0104]

[0105] [Chemical Formula 1a]

[0106]

[0107]

[0108] In each of the above chemical formulas 1 and 1a, the symbol * represents the point where the moiety A and the single ion-conducting functional group are combined.

[0109]

[0110] In a specific embodiment of the present invention, the moiety A is introduced with a single ion-conducting functional group and may include a vinyl group at the terminal. The moiety A may be derived from a compound in which the vinyl group is directly bonded to the single ion-conducting functional group, or from a compound in which the vinyl group is connected to the ion-conducting functional group via a linker. The vinyl group may include an alkylated vinyl group, a substituted or unsubstituted allyl group, a styrene group, a (meth)acrylate, a vinylamide group, or two or more selected from these. The linker is, for example, an allyl linker, an aryl linker (-Ar-), an alkylene linker (-R-). 2 -), alkyl group including ester group (-O-CO-R 2 -), amide bond, alkyl bond (-NH-R 2 -) or may include two or more selected from these. Herein, the above R 2 can be a substituted or unsubstituted alkylene group with 5 or fewer carbon atoms.

[0111] In a specific embodiment of the present invention, the moiety A may be derived from one or more compounds of the following chemical formulas 2a to 2h.

[0112]

[0113] [Chemical Formulas 2a to 2h]

[0114]

[0115]

[0116]

[0117]

[0118] In one embodiment of the present invention, the moiety A may comprise one derived from at least one compound of formulas 2a to 2e.

[0119] Preferably, in one embodiment of the present invention, the moiety A may be a (meth)acrylate-derived structure terminally substituted with the single ion-conducting functional group and may be grafted to the main chain by its acrylate group.

[0120] In a specific embodiment of the present invention, the styrene-based polymer having a hyper-crosslinked structure may be a compound represented by the following chemical formula 3.

[0121]

[0122] [Chemical Formula 3]

[0123]

[0124] In the above chemical formula 3, n, m, l, and k may each be independently integers greater than or equal to 1. In a specific embodiment, the ratio of n:m+l may be 1:30 to 70. For example, n:m+l may be 1:50.

[0125] Additionally, referring to Chemical Formula 3 above, at least two units may have benzene rings bonded to each other. The bonding between the benzene rings may be formed between adjacent units. Along with or independently thereof, at least one unit may have a polystyrene chain grafted thereon. In this manner, the porous particle may form a supercrosslinked structure. In Chemical Formula 3 above, the wavy line indicates the grafting of the polystyrene chain. In one embodiment of the present invention, in addition to the main chain, one or more bonds between the benzene rings may be formed in the polystyrene chain grafted to the main chain. Meanwhile, referring to Chemical Formula 3 above, one or more repeating units are bonded to the aforementioned moieter A.

[0126]

[0127] In one embodiment of the present invention, the protective layer may contain 5 wt% to 70 wt% of the porous particles relative to 100 wt% of the protective layer. If the porous particles in the protective layer exceed 70 wt%, the protective layer is brittle. Additionally, durability may be reduced, such as by uneven coating surfaces or peeling of the coating layer. In such cases, ion conductivity is low, and the effect of cathode protection may be reduced. On the other hand, if the content of porous particles is too low, there is a problem in that the effect of single ion transfer is not exhibited.

[0128]

[0129] Meanwhile, in one embodiment of the present invention, the porous particles may have a particle size ranging from 100 nm to 2 µm. When the particle size of the porous particles satisfies the above range, the porous particles may exhibit uniform dispersibility without aggregating within the polymer matrix. More preferably, the particle size may have a range ranging from 200 nm to 1.5 µm. In this specification, the particle size may be based on the longest diameter of the particle. Alternatively, in the present invention, the particle size may be defined as the particle size (z-average) measured using the Dynamic Light Scattering (DLS) method. The particle size measured by this may also be referred to as the hydrodynamic diameter.

[0130]

[0131] matrix

[0132] Meanwhile, the polymer matrix may include a fluorinated polymer. The fluorinated polymer refers to a polyolefin in which some or all of the hydrogen atoms are substituted with fluorine atoms. Examples of such fluorinated polymers include vinylidene fluoride polymers containing vinylidene fluoride as a polymerization unit, and polyterifolium fluoroethylene (PTFE). For example, the fluorinated polymer may include a vinylidene fluoride polymer. The vinylidene fluoride polymer may include vinylidene fluoride units, and may also include other polymerization units capable of polymerizing with vinylidene fluoride units. Examples of such polymerization units include hexafluoroethylene (HFP), chlorotrifluoroethylene (CTFE), chlorofluoroethylene (CFE), tetrafluoroethylene (TFE), and trifluoroethylene (TrFE).

[0133] In one embodiment of the present invention, the fluorine-based polymer may have a weight-average molecular weight (Mw) of 100,000 to 1,000,000, and for example, a material with a weight of about 500,000 to 600,000 may be used. Meanwhile, the glass transition temperature of the fluorine-based polymer is not particularly limited but may have a range of about -50°C to -10°C.

[0134] In one embodiment of the present invention, the glass transition temperature (Tg) can be measured using a differential scanning calorimeter. Any equipment capable of measuring the Tg of polymer materials can be used as the differential scanning calorimeter. For example, the DSC 2910 equipment from TA Instruments can be used. In a specific embodiment, the glass transition temperature can be measured by preparing a sample for measurement, raising it from room temperature to 150°C or higher, for example, 200°C at a predetermined rate, then cooling it down, and reheating it at a predetermined rate. The heating and cooling rates can be appropriately controlled within 5°C / min to 15°C / min, and the cooling temperature can be reduced to approximately -50°C or lower, for example, -70°C. It goes without saying that such measuring devices and measurement conditions can be appropriately adjusted by a person skilled in the art depending on the sample.

[0135]

[0136] Meanwhile, in one embodiment of the present invention, the weight-average molecular weight can be measured using gel permeation chromatography (GPC). Any GPC device capable of measuring the weight-average molecular weight of polymer materials can be used. For example, Waters’ high temperature PL 220 device can be used. In a specific embodiment, dimethylformamide with a predetermined amount of LiBr added can be used as the solvent for measuring the molecular weight. The operating conditions can be controlled to about 50°C to 100°C, and the flow rate can be controlled within about 0.5 mL / min to 2.0 mL / min. In addition, the value can be corrected using polystyrene having an average molecular weight in the range of 2,000 to 2,000,000 g / mol as a standard sample. However, it goes without saying that such measuring devices and measuring conditions can be appropriately adjusted by a person skilled in the art depending on the sample, etc.

[0137]

[0138] In one embodiment of the present invention, the protective layer may comprise a polymer matrix in an amount of 30 wt% to 95 wt%, preferably 50 wt% to 90 wt%, or about 70 wt% to 90 wt% relative to 100 wt% of the protective layer. For example, the matrix may comprise about 75 wt% to 85 wt% of the protective layer. The porous particles and the matrix may comprise 90 wt% or more, 95 wt% or more, or 99 wt% or more by weight ratio in 100 wt% of the protective layer, and for example, the protective layer may be composed of porous particles and a matrix. The porous particles and the matrix in the protective layer may comprise 15:85 to 25:75 by weight ratio.

[0139] If the polymer matrix (PVDF) in the above protective layer is too small, the protective layer becomes brittle, resulting in poor coating of the cathode surface, reduced ion conductivity, inability to perform its role as a cathode protective layer, and inability to achieve the desired level of single-ion transport effect.

[0140]

[0141] Method for manufacturing a protective layer

[0142] Next, a method for manufacturing the above protective layer is described.

[0143] First, a precursor (Poly(chloro-methyl styrene), PCMS) is prepared by polymerizing chloromethylstyrene and divinylbenzene using suspension polymerization or dispersion polymerization methods. The polymerization may be carried out by a radical polymerization reaction using an initiator, and while an azo-based initiator may be used, it is not limited thereto. Next, to the precursor (PCMS) prepared in the previous step, substances such as AlCl3, FeCl3, etc. A supercrosslinked xPCMS structure can be formed by carrying out the Friedel-Crafts reaction using a Lewis acid catalyst. In the above reaction, crosslinking between aromatic rings can be formed.

[0144] Next, the prepared xPCMS and single ion conductors are subjected to an SI-ATRP reaction with a terminally substituted acrylate-derived compound to graft the single ion conductors onto the surface of the porous particles.

[0145]

[0146] Specifically, the above reaction mechanism can be explained as shown in Reaction Scheme 1 below.

[0147]

[0148] [Reaction Equation 1]

[0149]

[0150]

[0151] The porous particles according to the present invention can be obtained by the method described above. However, the method is not particularly limited to the method described above, as long as it is a method capable of obtaining porous particles of the structure described above.

[0152]

[0153] Subsequently, a coating composition is prepared by mixing the porous particles and a fluorine-based polymer, and the same is coated onto the surface of the cathode active material layer to manufacture a cathode. The coating composition is not particularly limited to a composition in which the fluorine-based polymer is melted to form a polymer solution and the porous particles are dispersed. In a specific embodiment, the coating composition may use THF (tetrahydrofuran), NMP (n-methyl-2-pyrrolidone), dioxane (1,4-dioxane), diethyl ether, methyl tetrahydrofuran (Methyl-THF), acetone, DMF (Dimethylformamide), DMAc (Dimethylacetamide), DMSO (Dimethyl sulfoxide), etc. as solvents. One or more of these may be used. However, it is not particularly limited thereto, and any solvent capable of dissolving the fluorine-based polymer resin may be used without limitation.

[0154]

[0155] lithium-sulfur battery

[0156] In one embodiment of the present invention, the negative electrode may be applied to the negative electrode of a lithium-sulfur battery. The lithium-sulfur secondary battery may include a positive electrode, a negative electrode, and an electrolyte, and the negative electrode may be according to the present invention and may refer to the foregoing description.

[0157]

[0158] The positive electrode of the above lithium-sulfur battery may include a positive electrode current collector and a positive electrode active material layer coated on one or both sides of the positive electrode current collector.

[0159] The positive current collector is intended to support the positive active material and is the same as described in the section on the current collector supporting the negative electrode.

[0160] The above positive active material layer may include a positive active material and may further include a conductive material, a binder, an additive, etc.

[0161] The above positive active material may include sulfur, particularly elemental sulfur (S8), sulfur-based compounds, or both. The above positive active material may include inorganic sulfur (S8), Li2S n (n≥1), disulfide compounds, organic sulfur compounds and carbon-sulfur polymers ((C2S x It may include one or more selected from the group consisting of )n, x= 2.5 ~ 50, n≥2). Preferably, the positive electrode active material may include inorganic sulfur (S8).

[0162] Since the sulfur included in the above-mentioned positive electrode active material does not possess electrical conductivity on its own, it can be used in combination with a conductive material such as a carbon material. Therefore, sulfur may be included in the form of a sulfur-carbon composite, and preferably, the positive electrode active material may be a sulfur-carbon composite.

[0163] The carbon included in the above sulfur-carbon composite may be a porous carbon material and may provide a framework capable of uniformly and stably fixing sulfur, and may compensate for the low electrical conductivity of sulfur to allow electrochemical reactions to proceed smoothly.

[0164] The porous carbon material described above can generally be manufactured by carbonizing various carbonaceous precursors. The porous carbon material may contain non-uniform pores internally, the average diameter of the pores may be in the range of 1 to 200 nm, and the porosity may be in the range of 10 to 90% of the total volume of the porous carbon material. The method for measuring porosity in the present invention is not particularly limited as long as it is a known porosity measurement method. For example, a known Hg porosimeter may be used, or it may be measured using a mercury porosimeter (Micromeritics AUTOPORE V), etc. Alternatively, it may be measured according to the BET (Brunauer-Emmett-Teller) method using nitrogen gas or ASTM D-2873. Alternatively, the true density can be calculated from the density (apparent density) of the sample being measured, the composition ratio of the materials contained in the sample being measured, and the density of each component, and the porosity of the electrode can be measured by calculating the difference between the apparent density and the true density (net density). For example, the porosity can be calculated by the following Equation 1.

[0165]

[0166] [Equation 1]

[0167] Porosity (Volume %) = {1 - (Apparent Density / True Density)} x 100

[0168] In the above Equation 1, the apparent density can be calculated from the following Equation 2.

[0169]

[0170] [Equation 2]

[0171] Apparent density (g / cm³) 3 ) = (Weight of electrode (g)) / {(Thickness of electrode (cm))x(Area of ​​electrode (cm²)} 2 ))}

[0172]

[0173] Apparent density, or generally bulk density, is a measure indicating how much space a material occupies per unit volume, including the voids or empty spaces contained within it. In other words, apparent density includes the material in its solid state as well as the voids within its volume. Apparent density can be calculated by dividing the mass of the material by its total volume. This includes all pores or empty spaces within the material. The formula for calculating apparent density is as follows:

[0174]

[0175] (Equation) Apparent Density = Mass / Total Volume

[0176]

[0177] The above mass can be measured using a balance. In the case of materials of a regular shape (e.g., cube, cylinder, etc.), the corresponding dimensions can be measured using appropriate tools such as a tape measure or calipers, which is a method widely known in the art to which the invention pertains. In the case of samples of an irregular shape, the volume can be measured by measuring the displacement of the liquid to determine the known change in volume. The change in volume may be equal to the volume of the material. A person skilled in the art may apply other known methods for measuring the volume or apparent density.

[0178] Net density (true density) refers to the density of a material without considering any voids or pores contained within it. It is the value obtained by dividing the mass of a solid material by its actual volume, excluding empty spaces from the volume. Net density can be calculated by dividing the mass of the material by its solid, non-empty volume. The formula for calculating net density is as follows:

[0179]

[0180] (Equation) True density = Mass / Solid volume (void volume not considered)

[0181]

[0182] Unlike apparent density, true density, which does not take into account the total volume excluding voids, represents the intrinsic density of the material. True density can be determined according to the methods mentioned above, or using the gas pollnometer method according to ISO 12154:2014 or other measurement methods known to experts in the field.

[0183]

[0184] If the average diameter of the pores is smaller than the above range, the pore size is merely at the molecular level, making sulfur impregnation impossible. Conversely, if the average diameter of the pores exceeds the above range, the mechanical strength of the porous carbon material weakens, making it undesirable for application in the electrode manufacturing process.

[0185] The shape of the above porous carbon material may be spherical, rod, needle, plate, tube, or bulk, and can be used without limitation as long as it is commonly used in lithium-sulfur batteries.

[0186] The porous carbon material may have a porous structure or a high specific surface area, and may be one commonly used in the industry. For example, the porous carbon material may include graphite; graphene; carbon black such as Denka black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black; carbon nanotubes (CNT) such as single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT); carbon fibers such as graphite nanofibers (GNF), carbon nanofibers (CNF), and activated carbon fibers (ACF); graphite such as natural graphite, artificial graphite, and expanded graphite; activated carbon, etc. Preferably, the porous carbon material may be a carbon nanotube.

[0187] The above sulfur-carbon composite may contain a sulfur content of 60 to 90 parts by weight, preferably 65 to 85 parts by weight, and more preferably 70 to 80 parts by weight, per 100 parts by weight of the sulfur-carbon composite. If the sulfur content is lower than the above range, the content of porous carbon material within the sulfur-carbon composite increases relatively, thereby increasing its specific surface area and consequently increasing the amount of binder used relative to the sulfur content during the manufacture of the anode. This increase in the amount of binder used ultimately increases the sheet resistance of the anode and acts as an insulator that blocks the passage of electrons, thereby degrading the performance of the battery. Conversely, if the sulfur content exceeds the above range, sulfur that cannot bond with the porous carbon material aggregates or re-leaches to the surface of the porous carbon material, making it difficult to accept electrons and unable to participate in electrochemical reactions, resulting in a decrease in battery capacity.

[0188] In addition, in the sulfur-carbon composite, sulfur may be located on the surface of the aforementioned porous carbon material, for example, on at least one of the inner and outer surfaces of the porous carbon material. In this case, sulfur may be present in an area of ​​less than 100%, preferably 1 to 95%, and more preferably 60 to 90% of the total inner and outer surfaces of the porous carbon material. When sulfur is present on the inner and outer surfaces of the porous carbon material within the above range, it can exhibit maximum effects in terms of electron transfer area and wettability with the electrolyte. Specifically, since sulfur is thinly and uniformly impregnated on the inner and outer surfaces of the porous carbon material within the above range, the electron transfer contact area can be increased during the charge-discharge process. If sulfur is located on 100% of the total area of ​​the inner and outer surfaces of the porous carbon material, the carbon material is completely covered with sulfur, resulting in poor wettability with the electrolyte and poor contact with the included electrically conductive material, so it cannot receive electrons from the electrode and cannot participate in the electrochemical reaction.

[0189] The method for manufacturing the above sulfur-carbon composite is not particularly limited in the present invention, and methods commonly used in the art may be used. For example, a method of simply mixing sulfur and a porous carbon material and then heat-treating them to form a composite may be used.

[0190] In addition to the above, the positive electrode active material may further include transition metal elements, Group IIIA elements, Group IVA elements, sulfur compounds of these elements, alloys of these elements and sulfur, and one or more additives selected from the aforementioned components.

[0191] The above transition metal elements may include Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Os, Ir, Pt, Au, Hg, etc., and group IIIA elements may include Al, Ga, In, Tl, etc., and group IVA elements may include Ge, Sn, Pb, etc.

[0192] The sulfur may be included in an amount of 40 to 95 weight%, preferably 50 to 90 weight%, and more preferably 60 to 85 weight%, relative to 100 weight% of the positive active material layer constituting the positive electrode. In one embodiment of the present invention, when a sulfur-carbon composite is used as the positive active material, the sulfur-carbon composite may be included in an amount of 90 weight% to 97 weight% relative to 100 weight% of the positive active material layer. If the content of the positive active material is less than the above range, it is difficult to sufficiently exhibit the electrochemical reaction of the positive electrode. Conversely, if the content exceeds the above range, the content of the conductive material and binder described below is relatively insufficient, causing the resistance of the positive electrode to increase and the physical properties of the positive electrode to deteriorate.

[0193] The above positive active material layer may optionally further include a conductive material that enables electrons to move smoothly within the positive electrode (specifically, the positive active material) and a binder that effectively attaches the positive active material to the current collector.

[0194] The above conductive material is a substance that electrically connects the electrolyte and the positive active material, serving as a pathway for electrons to move from the current collector to the positive active material. The above conductive material may be used without limitation as long as it possesses electrical conductivity.

[0195] For example, the conductive material may be used alone or in combination with graphite, such as natural graphite or artificial graphite; carbon black, such as Super-P, Denka Black, Acetylene Black, Ketjen Black, Channel Black, Furnace Black, Lamp Black, and Thermal Black; carbon derivatives, such as carbon nanotubes and fullerenes; electrically conductive fibers, such as carbon fibers and metal fibers; fluorocarbon; metal powders, such as aluminum and nickel powders; or electrically conductive polymers, such as polyaniline, polythiophene, polyacetylene, and polypyrrole.

[0196] The conductive material may be included in an amount of 0.01 to 30 weight% relative to 100 weight% of the total positive active material layer constituting the positive electrode. If the content of the conductive material is lower than the above range, it is difficult for electrons to move between the positive active material and the current collector, resulting in a decrease in voltage and capacity. Conversely, if the content exceeds the above range, the relative proportion of the positive active material decreases, which may reduce the total energy (charge amount) of the battery. Therefore, it is desirable to determine the content of the conductive material to be an appropriate amount within the aforementioned range.

[0197] The binder serves to hold the positive active material in the positive current collector and organically connect the positive active materials to increase the bonding strength between them, and any binder known in the art may be used.

[0198] For example, the binder comprises a fluoropolymer-based binder including polyvinylidene fluoride (PVdF) or polytetrafluoroethylene (PTFE); a rubber-based binder including styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber and styrene-isoprene rubber; a cellulose-based binder including carboxymethylcellulose (CMC), starch, hydroxypropylcellulose and regenerated cellulose; a polyalcohol-based binder; a polyolefin-based binder including polyethylene and polypropylene; a polyimide-based binder; a polyester-based binder; and a silane-based binder, or a mixture or copolymer of two or more of these.

[0199] The content of the binder may be 0.5 to 30 weight percent based on 100 weight percent of the total positive active material layer constituting the positive electrode. If the binder content is less than 0.5 weight percent, the physical properties of the positive electrode may deteriorate, causing the positive active material and the conductive material to delaminate. If the content exceeds the above range, the ratio of the positive active material to the conductive material within the positive electrode may decrease relatively, which may reduce the capacity of the battery. Therefore, it is desirable to determine the binder content to an appropriate amount within the aforementioned range.

[0200] In the present invention, the method of manufacturing the anode is not particularly limited, and methods known to those skilled in the art or various modified methods may be used.

[0201] For example, the anode can be manufactured by preparing an anode slurry composition containing the above-described components and then applying it to at least one surface of an anode current collector.

[0202] The above-described anode slurry composition comprises the anode active material, conductive material, and binder described above, and may further include solvents other than those mentioned above.

[0203] The above solvent may be one capable of uniformly dispersing the positive active material, the conductive material, and the binder. Such a solvent may be an aqueous solvent, and water is most preferable; in this case, the water may be distilled water or deionized water. However, it is not necessarily limited thereto, and if necessary, a lower alcohol that can be easily mixed with water may be used. Examples of lower alcohols include methanol, ethanol, propanol, isopropanol, butanol, etc., and preferably, they may be used mixed with water.

[0204] The above solvent may be included at a concentration that facilitates coating, and the specific content varies depending on the application method and device.

[0205] The above anode slurry composition may additionally include materials commonly used in the relevant technical field to enhance its function as needed. Examples include viscosity modifiers, fluidizing agents, fillers, etc.

[0206] In the present invention, the method of applying the anode slurry composition is not particularly limited, and methods such as the doctor blade method, die casting method, comma coating method, and screen printing method may be used. In addition, after forming on a separate substrate, the anode slurry can be applied onto the anode current collector by a press or lamination method.

[0207] After the above coating, a drying process may be performed to remove the solvent. The drying process is performed at a temperature and time sufficient to remove the solvent, and since the conditions may vary depending on the type of solvent, they are not specifically limited in the present invention. Examples of drying methods may include drying methods using warm air, hot air, or low-humidity air, vacuum drying methods, and drying methods using (far-infrared) radiation or electron beam irradiation. The drying speed can generally be adjusted so that the solvent is removed as quickly as possible within a speed range where cracks do not occur in the positive active material layer due to stress concentration and the positive active material layer does not peel off from the positive current collector.

[0208] In addition, the density of the positive active material within the positive electrode can be increased by applying pressure to the current collector after the above drying. Examples of pressing methods include mold pressing and roll pressing.

[0209] The porosity of the anode, specifically the anode active material layer manufactured by the composition and manufacturing method described above, may be 50 vol% to 80 vol%, preferably 60 vol% to 75 vol%. If the porosity of the anode is less than 50 vol%, the packing density of the anode slurry composition, which includes the anode active material, conductive material, and binder, becomes too high. Consequently, a sufficient amount of electrolyte capable of exhibiting ion conduction and / or electrical conductivity cannot be maintained between the anode and the cathode, leading to a deterioration in the output characteristics or cycle characteristics of the battery and a severe decrease in overvoltage and discharge capacity. Conversely, if the porosity of the anode exceeds 80 vol% and is excessively high, the physical and electrical connection with the current collector deteriorates, resulting in reduced adhesion and difficulty in reaction. Additionally, the increased pores are filled with electrolyte, causing a decrease in the energy density of the battery. Therefore, the porosity of the anode is appropriately adjusted within the above range.

[0210] In addition, the loading amount of heavy sulfur in the anode according to the present invention, that is, the mass of sulfur per unit area of ​​the anode active material layer, is 0.5 to 15 mg / cm² 2 , preferably 1 to 10 mg / cm² 2 It could be.

[0211]

[0212] The lithium-sulfur battery according to the present invention may include an electrolyte. The electrolyte contains lithium ions and is intended to cause electrochemical oxidation or reduction reactions at the positive and negative electrodes.

[0213] The above electrolyte may be a non-aqueous electrolyte or a solid electrolyte that does not react with lithium metal, but preferably may be a non-aqueous electrolyte. The above non-aqueous electrolyte comprises a lithium salt and an organic solvent.

[0214] The above lithium salt may further include lithium salts commonly used in electrolytes for lithium secondary batteries. Such lithium salts include LiCl, LiBr, LiI, LiClO4, LiBF4, and LiB 10 Cl 10 It may include LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, (CF3SO2)2NLi, LiN(SO2F)2, lithium chloroborane, lithium lower aliphatic carboxylate, tetraphenyl lithium borate, lithium imide, lithium bis(fluorosulfonyl)imide (LiFSI), LiHFDF, LiBETi, or two or more of these. For example, the lithium salt may include (CF3SO2)2NLi.

[0215] The concentration of the lithium salt in the above electrolyte may be 0.2 to 2 M, specifically 0.4 to 2 M, more specifically 0.4 to 1.7 M, depending on various factors such as the precise composition of the electrolyte solvent mixture, the solubility of the salt, conductivity, the conductivity of the dissolved salt, the charge / discharge conditions of the battery, the operating temperature, and other factors known in the field of lithium batteries. If the concentration of the lithium salt is less than 0.2 M, the conductivity of the electrolyte decreases, which may degrade the performance of the electrolyte. If the concentration of the lithium salt exceeds 2 M, the viscosity of the electrolyte increases, which may reduce the mobility of lithium ions.

[0216]

[0217] In one embodiment of the present invention, the organic solvent included in the electrolyte may be any solvent commonly used in lithium secondary battery electrolytes without limitation. For example, ethers, esters, amides, chain carbonates, cyclic carbonates, etc., may be used alone or in combination of two or more. Among these, ether-based compounds may be included as a representative example.

[0218]

[0219] The above ether-based compounds may include acyclic ethers and cyclic ethers.

[0220] For example, the above-mentioned acyclic ether may be one or more selected from the group consisting of dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, dimethoxyethane, diethoxyethane, ethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol methyl ethyl ether, polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, and polyethylene glycol methyl ethyl ether.

[0221] For example, the cyclic ether is 1,3-dioxolane, 4,5-dimethyl-dioxolane, 4,5-diethyl-dioxolane, 4-methyl-1,3-dioxolane, 4-ethyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, 2,5-dimethoxytetrahydrofuran, 2-ethoxytetrahydrofuran, 2-methyl-1,3-dioxolane, 2-vinyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxolane, 2-methoxy-1,3-dioxolane, 2-ethyl-2-methyl-1,3-dioxolane, tetrahydropyran, 1,4-dioxane, 1,2-dimethoxybenzene, It may be one or more selected from the group consisting of 1,3-dimethoxybenzene, 1,4-dimethoxybenzene, and isosorbid dimethyl ether, but is not limited thereto.

[0222] Examples of the esters of the above organic solvents include, but are not limited to, any one selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone and mixtures of two or more of these.

[0223] Specific examples of the above linear carbonate compounds include, but are not limited to, any one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate and ethylpropyl carbonate, or a mixture of two or more of these.

[0224] In addition, specific examples of the above-mentioned cyclic carbonate compounds may include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate, vinylethylene carbonate, and their halides, or mixtures of two or more of these. Examples of such halides include, but are not limited to, fluoroethylene carbonate (FEC).

[0225] In one embodiment of the present invention, it is preferable that the organic solvent has a solubility of the lithium salt exceeding 0.1 M. In this regard, the organic solvent may include dimethoxyethane (DME).

[0226] Meanwhile, in one embodiment of the present invention, the electrolyte may further include a non-solvent in an amount of 50% by weight or less, 30% by weight or less, or 25% by weight or less relative to 100% by weight of the organic solvent. The non-solvent means having a solubility of lithium salt of 0.1M or less. The non-solvent may include 2-Me-Furan.

[0227] In one embodiment of the present invention, the electrolyte may be a mixture of 1,3-Dioxolane (DOL) and 1,2-Dimethoxyethane (DME) mixed in a volume ratio of 1:1 as an organic solvent.

[0228] The above electrolyte may further include a nitric acid or nitrite-based compound as an additive in addition to the aforementioned electrolyte salt and organic solvent. The nitric acid or nitrite-based compound has the effect of improving charge / discharge efficiency by forming a stable film on the lithium metal electrode serving as the negative electrode.

[0229] The above nitric acid or nitrite-based compounds are not specifically limited in the present invention, but include inorganic nitric acid or nitric acid compounds such as lithium nitrate (LiNO3), potassium nitrate (KNO3), cesium nitrate (CsNO3), barium nitrate (Ba(NO3)2), ammonium nitrate (NH4NO3), lithium nitrite (LiNO2), potassium nitrite (KNO2), cesium nitrite (CsNO2), and ammonium nitrite (NH4NO2); organic nitric acid or nitrite compounds such as methyl nitrate, dialkylimidazolium nitrate, guanidine nitrate, imidazolium nitrate, pyridinium nitrate, ethyl nitrite, propyl nitrite, butyl nitrite, pentyl nitrite, and octyl nitrite; It may be one or more selected from organic nitro compounds such as nitromethane, nitropropane, nitrobutane, nitrobenzene, dinitrobenzene, nitropyridine, dinitropyridine, nitrotoluene, dinitrotoluene, and combinations thereof, and mixtures of selected components among these, preferably lithium nitrate is used. In one embodiment of the present invention, the nitrite compound may be included in a ratio of about 6 weight% relative to 100 weight% of the electrolyte.

[0230]

[0231] The above-mentioned electrolyte injection can be performed at an appropriate stage of the electrochemical device manufacturing process depending on the manufacturing process and required characteristics of the final product. That is, the injection can be performed before the electrochemical device assembly or at the final stage of the electrochemical device assembly.

[0232]

[0233] The lithium-sulfur secondary battery according to the present invention may include additional components known in the art, for example, may additionally include a separator or a solid electrolyte membrane for electrical insulation of the negative electrode and the positive electrode.

[0234] In one embodiment, the lithium-sulfur battery may have a separator interposed between the positive electrode and the negative electrode. The separator may be made of a porous, non-conductive, or insulating material that separates or insulates the positive electrode and the negative electrode and enables the transport of lithium ions between the positive electrode and the negative electrode. The separator may be used without particular limitation as long as it is used as a separator in a conventional lithium-sulfur battery. The separator may be an independent member such as a film or may include a coating layer added to the positive electrode and / or the negative electrode.

[0235] It is desirable that the separator has excellent wettability to the electrolyte and low resistance to ion movement of the electrolyte. The separator may be made of a porous substrate, and any porous substrate commonly used in lithium-sulfur batteries may be used. A porous polymer film may be used alone or in a laminated form. For example, a nonwoven fabric with a high melting point, such as glass fiber or polyethylene terephthalate fiber, or a polyolefin-based porous membrane may be used, but is not limited thereto.

[0236] The material of the porous substrate is not particularly limited in the present invention, and any material that is a porous substrate generally used in electrochemical devices may be used. For example, porous substrates may include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides, polyacetals, polycarbonates, polyimides, polyetheretherketones, polyethersulfones, polyphenylene oxide, polyphenylene sulfide, polyethylene naphthalate, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyacrylonitrile, cellulose, poly(p-phenylenebenzobisoxazole), polyarylates, etc.

[0237] The thickness of the porous substrate is not particularly limited, but may be 1 to 100 μm, preferably 5 to 50 μm. Although the thickness range of the porous substrate is not specifically limited to the above range, if the thickness is excessively thin compared to the lower limit, the mechanical properties may deteriorate, and the separator may be easily damaged during battery use.

[0238] The average diameter and porosity of the pores present in the porous substrate are not particularly limited, but may be 0.001 μm to 50 μm and 10 vol% to 95 vol%, respectively. The method for measuring porosity may refer to the above-described content.

[0239]

[0240] The lithium secondary battery according to the present invention can be manufactured through lamination, stacking, and folding processes of a separator and an electrode in addition to a conventional winding process.

[0241] The shape of the above lithium secondary battery is not particularly limited and can be of various shapes, such as a cylindrical shape, a laminate shape, or a coin shape.

[0242] In addition, the present invention provides a battery module comprising the above-described lithium-sulfur battery as a unit cell.

[0243] The above battery module can be used as a power source for medium to large-sized devices that require high-temperature stability, long-cycle characteristics, and high-capacity characteristics.

[0244] Examples of such medium-to-large devices may include, but are not limited to, power tools driven and moved by electric motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), etc.; electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf carts; power storage systems, etc.

[0245]

[0246] Specific embodiments of the present invention are described below. However, the following embodiments are merely illustrative of the present invention, and various changes and modifications are possible within the scope of the present invention, and it will be obvious to those skilled in the art that such changes and modifications are also within the scope of the present invention. Meanwhile, the aforementioned embodiments may each be implemented independently. Alternatively, it is obvious that two or more of the aforementioned embodiments may be implemented in combination.

[0247]

[0248] Preparation of porous particles

[0249] [PCMS Manufacturing]

[0250] First, a 500 ml three-necked round-bottom flask was evacuated with nitrogen gas, and 5 ml of chloromethylstyrene (CMS), 0.1 ml of divinylbenzene (DVB), and 100 ml of deionized water were added. Subsequently, 0.0560 g of V-50 (2,2'-Azobis(2-methylpropionamidine)dihydrochloride) (1 wt% of the monomer) was dissolved in 1 ml of deionized water as an initiator and added to the flask. The mixture was then reacted by stirring with a mechanical stirrer at 75 °C for 24 hours. After the reaction, the mixture was washed five times with deionized water and dried under vacuum conditions at 60 °C. The specific surface area, total pore volume, and average pore size of the obtained PCMS are summarized in Table 1 below.

[0251]

[0252] [xPCMS Manufacturing]

[0253] After setting a 250 ml round-bottom flask to a nitrogen atmosphere, 3.5 g of PCMS and 50 ml of 1,2-dichloroethane were added and stirred overnight at room temperature. Next, 3.7 g of FeCl3 was dissolved in 12 ml of 1,2-dichloroethane and added to the flask, after which the reaction was carried out by stirring at 80 ℃ for 24 hours. After the reaction, the mixture was washed three times with a mixed solution of 600 ml of water, 300 ml of acetone, and 100 ml of hydrochloric acid, and then dried under vacuum at 60 ℃ to obtain xPCMS. The specific surface area, total pore volume, and average pore size of the obtained xPCMS are summarized in Table 1 below.

[0254]

[0255] [Manufacture of f-xPCMS (xPCMS-gP(LiMTFSI))]

[0256] First, a 100 ml shrink flask was set to a nitrogen atmosphere, and then 0.2 g of xPCMS, 0.2 g of LiMTFSI, and 4 ml of DMF were added. LiMTFSI can be represented by Chemical Formula 2c above. Subsequently, oxygen and external air were removed from the reactants through three freeze-pump-thaw cycles, 22.5 mg of CuBr was added, and the freeze-pump-thaw cycle was repeated twice. Then, 33 µl of PMDETA was added, and the freeze-pump-thaw cycle was repeated three more times. Next, the mixture was washed three times each with water, methanol, and acetone, and dried under vacuum conditions at 60 °C. Porous particles were obtained by this method. For the obtained f-xPCMS, the specific surface area, total pore volume, and average pore size are summarized in Table 1 below.

[0257]

[0258] Specific surface area [m 2 / g]Total pore volume (p / p0=0.990) [cm 3 / g]Average pore diameter [nm]PCMS4.1460.0395638.17xPCMS1,3300.78442.396f-xPCMS1,0620.56602.133

[0259]

[0260] As shown in Table 1 above, the f-xPCMS obtained in the above preparation example has a very large specific surface area and porous characteristics with pores at the nanometer level. The porosity of the protective layer could be secured by introducing such porous particles.

[0261] Figure 1 shows the FT-IR analysis results of the products manufactured at each stage in the manufacture of the protective layer according to the present invention. Referring to this, it was confirmed that hyper cross-linking occurred well in xPCMS through the reduction of the C-Cl peak. In addition, it was confirmed that SI-ATRP (Surface-initiated atom transfer radical polymerization) occurred well through the assignment of characteristic peaks of P(LiMTFSI).

[0262]

[0263] Meanwhile, FIGS. 3 to 5 show SEM images of the manufacturing results at each stage in the manufacture of a protective layer according to the present invention. Referring to these figures, it was confirmed that particles having a uniform shape were manufactured.

[0264]

[0265] In addition, Figures 6a to 6g respectively show TEM and SEM images of f-xPCMS according to the present embodiment, and each element constituting f-xPCMS was identified.

[0266]

[0267] Particle size distribution measurement

[0268] Figure 2 shows the size distribution of f-xPCMS particles obtained in Examples 1 to 5. The particle size distribution was confirmed using the Dynamic Light Scattering method, whereby the particle sizes were found to have a distribution of approximately 400 nm to 800 nm. Specifically, for the measurement method, a solution was prepared by dispersing the f-xPCMS particles in water at a concentration of 0.1 mg / mL, placing it in a quartz cuvette, and applying it to a DLS instrument.

[0269]

[0270] Method for measuring the total pore volume, pore size, and specific surface area of ​​particles

[0271] The specific surface area and total pore volume were measured using the Brunauer-Emmett-Teller (BET) method. The experiment was conducted under atmospheric pressure conditions (approximately 1 atm) at the nitrogen boiling point temperature of -196°C. The specific surface area was calculated based on the nitrogen adsorption amount measured at relative pressures (P / P0) ranging from 0.05 to 0.3, while the total pore volume was calculated based on the relative pressure (P / P0) of 0.990. Meanwhile, the average pore diameter was calculated using the equation below. In the equation below, a constant 4 was added to balance the ratio of volume to surface area of ​​circular or spherical pores.

[0272]

[0273] (Equation) Average pore diameter = {4 × (Total pore volume)} / Specific surface area

[0274]

[0275] In the above formula, the unit of total pore volume is cm³ 3 / g can be used. Also, in the above formula, the unit of specific surface area is cm² 2 / g can be used.

[0276]

[0277] Example: Preparation of the cathode

[0278] 2.55 g of THF and 0.45 g of NMP were mixed and added to a 20 ml vial. Subsequently, the porous particles obtained above and polyvinylidene fluoride (PVDF, 450 kDa) were added in the amounts shown in Table 2 below and stirred to prepare a coating composition. After sonicating the obtained coating composition for 20 minutes, 100 μm of the composition was dropped onto a lithium metal (thickness 200 μm) cathode active material using a micropipette, and the cathode was obtained by drying under room temperature and vacuum conditions. The thickness of the protective layer was approximately 5 μm. Figure 9 is an SEM image of the surface of the cathode prepared in Example 3, and by referring to this, it was confirmed that the protective layer coating was well formed.

[0279]

[0280] Porous particle fluorinated polymer Example 11.8 mg 9 mg Example 22.25 mg 9 mg Example 33 mg 9 mg Example 44.5 mg 9 mg Example 59 mg 9 mg Example 61.5 mg 9 mg

[0281]

[0282] Manufacturing of lithium-sulfur batteries

[0283] The anode and battery were prepared as follows. Sulfur and Ketjen black were mixed in a 7:3 weight ratio, ground using a mortar and pestle, and heat-treated at 155°C for 30 minutes to prepare an anode active material in the form of a sulfur / carbon composite. The prepared anode active material, PAA binder, and conductive material (Super P) were mixed in a weight ratio of 80:10:10, and then 3 wt% of PVA dispersant was added and mixed in an aqueous solution using a thinky mixer to prepare an anode slurry. The prepared anode slurry was coated onto aluminum foil to a thickness of 150 μm using a doctor blade, and then dried at 55°C for approximately 14 hours.

[0284] The anode prepared in this manner was assembled into a coin-type cell together with the cathodes of Examples 1 to 5. The anode active material loading amount of the anode was 2.60 mAh / cm² 2And, the porosity was 78%. Meanwhile, a 10㎛ polyethylene porous film (porosity 68%) was used as a separator.

[0285]

[0286] Comparative Example 1

[0287] A lithium-sulfur battery was prepared in the same manner as in Example 1, except that a lithium anode with a thickness of 200 μm without a protective layer was applied. Figure 10 shows an SEM image of the surface of the anode prepared in Comparative Example 1.

[0288]

[0289] Comparative Example 2

[0290] 2.55 g of THF and 0.45 g of NMP were mixed and added to a 20 ml vial. Then, 9 mg of polyvinylidene fluoride (PVDF, 450 kDa) was added and stirred to prepare a coating composition. After sonicating the obtained coating composition for 20 minutes, 100 μm of the composition was dropped onto a lithium metal (thickness 200 μm) which was the negative electrode active material using a micropipette, and the negative electrode was obtained by drying under room temperature and vacuum conditions. The thickness of the protective layer was approximately 5 μm. A lithium-sulfur battery was manufactured in the same manner as in Example 1, except for applying the negative electrode prepared in this way.

[0291]

[0292] Comparative Example 3

[0293] 2 ml of 1 M LiOH aqueous solution was added to 10 ml of 20 wt% Nafion aqueous solution (Chemous Inc.), and the mixture was stirred at 100°C for 2 hours. Afterward, the reaction mixture was sufficiently cooled, and residual LiOH and impurities were removed through a dialysis process. The purified solution was vacuum dried at 100°C to obtain lithium-ion substituted Nafion (LN). 9 mg of the obtained LN and 3 g of DMSO were placed in a 20 ml vial and stirred to prepare a coating composition. The formation of the negative electrode protective layer and the manufacturing process of the lithium-sulfur battery were carried out in the same manner as in Example 1. The Nafion used has the structure of Chemical Formula 4 below.

[0294]

[0295] [Chemical Formula 4]

[0296]

[0297]

[0298] In the above chemical formula 3, x and z represent integers from 1 to 10, y represents an integer less than 1000, and A represents the element Li.

[0299] Figure 14 shows the FT-IR spectrum of the synthesized lithium-substituted Nafion (LN). Referring to this, the characteristic peak of the -SO3H group has almost disappeared, and at approximately 1060 cm⁻¹ -1 SO3 in the vicinity - From the appearance of the ion absorption band, it can be confirmed that the sulfonic acid group was successfully substituted into the lithium sulfonate (-SO3Li) form. Also, at 1150 cm⁻¹ -1 The nearby CF stretching vibration peak is maintained, indicating that the fluorinated polymer main chain structure of Nafion was stably maintained even during the lithium substitution process.

[0300]

[0301] Comparative Example 4

[0302] Except for using 0.2 g of PEGMA (Mn=360, Sigma-Aldrich) instead of 0.2 g of LiMTFSI, the rest of the process was synthesized in the same manner as f-xPCMS (xPCMS-gP(LiMTFSI)). Figure 15 shows the FT-IR spectra of xPCMS and xPCMS-g-PPEGMA. In the xPCMS-g-PPEGMA spectrum, C-Cl (684 cm⁻¹), which was observed in xPCMS, -1 ) and C=C (1,645,989 cm -1 The peak disappears, and instead, C=O(1,725 ​​cm⁻¹) -1 ) and COC(1,260, 1,104 cm -1 A new peak appears. Also, at 2,916 cm -1 CH stretching vibrations of the PEG chain were detected in the vicinity. From these results, it can be seen that the double bond of PEGMA was opened and bonded to the chloromethyl group of xPCMS, thereby forming a graft copolymer (xPCMS-g-PPEGMA).

[0303] Subsequently, 2.25 mg of LN and 9 mg of xPCMS-g-PEGMA were dissolved in 3 g of DMSO to prepare a composition for LN / xPCMS-g-PEGMA coating.

[0304] Meanwhile, the formation of the negative electrode protective layer and the manufacturing process of the lithium-sulfur battery were carried out in the same manner as in Example 1.

[0305]

[0306] Evaluation of battery life characteristics (1) 0.2C charge / discharge conditions

[0307] For the batteries of Examples 1 to 5 and Comparative Examples 1 to 2, two discharges were performed at room temperature (25°C) at a rate of 0.1 C in the range of 2.5 V to 1.8 V, followed by repeated charge-discharge cycles at a rate of 0.2 C in the range of 1.8 V to 2.5 V. Figure 11 shows a graph of the discharge capacity measured according to the cycle. Referring to this, it was confirmed that the discharge capacity of Comparative Examples 1 and 2 was lower across the entire cycle range compared to the batteries of Examples 1 to 5. Comparative Example 1 exhibited a rapid capacity drop at the beginning of the cycle, indicating instability at the electrode-electrolyte interface, while Comparative Example 2 showed some improvement in initial stability due to the application of a single polymer protective layer, but a continuous decrease in capacity was observed thereafter. In contrast, Examples 1 to 5 all exhibited higher initial capacities and superior capacity retention rates than the Comparative Examples; in particular, Examples 2 to 5 showed approximately 700-750 mAh g as the cycle progressed. -1 A stable capacity of the level was maintained. This is interpreted as a result of the composite protective layer according to the present invention inducing uniform movement of lithium ions and suppressing interfacial resistance and dendrite growth, thereby significantly improving long-term cycle stability.

[0308] Meanwhile, FIG. 16 shows the results of measuring the change in discharge capacity of lithium-sulfur batteries with the protective layers of Comparative Examples 1 to 4 and Example 2 applied over 100 cycles at a rate of 0.2 C. Comparative Example 1 shows a rapid decrease in capacity, and Comparative Example 2 shows some stabilization effect, but the capacity decrease persists due to low ion conductivity. Comparative Example 3 is Li +Although conductivity was improved, resulting in a high capacity retention rate (75.7%) compared to Comparative Example 2, performance degradation occurred due to mechanical brittleness during long-term cycles. Comparative Example 4 showed a capacity retention rate of approximately 80% due to improved flexibility and interfacial adhesion caused by the PEGMA graft, but the capacity degradation was greater than that of Example 2, and performance also deteriorated in terms of long-term cycle stability. On the other hand, Example 2 was confirmed to exhibit the best cycle stability by maintaining a high capacity retention rate of 88.3% even after 100 cycles.

[0309]

[0310] Evaluation of Battery Life Characteristics (2) 0.5C Charge / Discharge Conditions

[0311] For the batteries of Examples 2, 3, and 6, and Comparative Examples 1 and 2, charge-discharge cycles were repeated at room temperature (25°C) at a rate of 0.5 C in the range of 1.8 V to 2.5 V. Figure 12 shows a graph of the discharge capacity measured according to the cycle. Referring to this, it was confirmed that the discharge capacity of Comparative Examples 1 and 2 was lower over the entire cycle range compared to the batteries of Examples 2, 3, and 6. In particular, the battery of Example 2 showed approximately 750 mAh g even after 50 cycles. -1 The best results were achieved by maintaining the above capacity. It was confirmed that the battery of the example exhibited superior discharge characteristics compared to the comparative example under high rate conditions, which appears to be a useful characteristic for use as a high-output power source.

[0312] Figure 13 shows the results of evaluating charge-discharge durability at a higher current density (0.5 C). As the current density increases, the initial capacity of all samples decreases, but Example 2 exhibits the best stability with a high capacity retention rate of 87.5%. On the other hand, Comparative Example 2 and Comparative Example 3 showed retention rates of 70.1% and approximately 72%, respectively, which is interpreted as being affected by increased charge transfer resistance and interfacial non-uniformity under high-speed charge-discharge conditions. From these results, it can be confirmed that the protective layer according to the present invention provides excellent cycle durability even under high-speed charge-discharge conditions by simultaneously securing mechanical stability, ion conductivity, and interfacial adhesion.

[0313]

[0314] Manufacturing of the protective layer

[0315] 2.55 g of THF and 0.45 g of NMP were mixed and added to a 20 ml vial. Subsequently, the porous particles obtained above and polyvinylidene fluoride (PVDF, 450 kDa) were added in the amounts specified in Table 3 below and stirred to prepare a composition for forming a protective layer. After sonicating the obtained composition for forming a protective layer for 20 minutes, the volumes specified in Table 3 below were dropped onto a slide glass (2.5 cm x 2.5 cm) using a micropipette, and a free-standing type protective layer was obtained by drying under room temperature and vacuum conditions. The thickness of the obtained protective layers was approximately 25 µm.

[0316]

[0317] Porous Particle Fluorinated Polymer Dropping Amount Example 1 - 215mg 75mg 360µl Example 2 - 218.75mg 75mg 375µl Example 3 - 225mg 75mg 400µl Example 4 - 237.5mg 75mg 450µl Example 5 - 275mg 75mg 600µl Example 6 - 212.5mg 75mg 350µl Comparative Example 2 - 2NA 75mg 300µl

[0318]

[0319] Ion conductivity measurement

[0320] The free-standing type protective layer obtained after drying was detached from the slide glass and impregnated in 1M (CF3SO2)2NLi in DIOX / DME (1:1 v / v%) + 2 wt% LiNO3 for 12 hours. Next, a symmetric coin-type cell was fabricated by interposing the protective layer between Su layers, and the ionic conductivity was calculated by measuring the resistance at 30°C using EIS (Electrochemical Impedance Spectroscopy). The calculation of ionic conductivity is given by Equation 1 below.

[0321]

[0322] [Formula 1]

[0323] Ionic conductivity (σ(S cm) -1 ))=(1 / R b ) X (Length(l) / Area(A ))

[0324]

[0325] In Equation 1 above, l is the thickness of the cell, A is the area of ​​the cell, and R b represents the resistance of the cell.

[0326]

[0327] Measurement of electrolyte impregnation of the protective film

[0328] The electrolyte impregnation of the protective film was calculated by measuring the initial weight of the protective film and its weight after impregnation in the electrolyte, determining the change in weight, and expressing the result as a percentage of the change relative to the initial weight.

[0329]

[0330] Measurement of porosity of the protective layer For each protective layer obtained above, the porosity was calculated according to Equation 1 below. The porosity measurement above calculated the porosity of the electrode from the difference between the apparent density and the net density of each component included in the protective layer. The calculated results are summarized in Table 4 below.

[0331]

[0332] [Equation 1]

[0333] Porosity (Volume %) = {1 - (Apparent Density / True Density)} x 100

[0334]

[0335] Meanwhile, the apparent density in the above Equation 1 can be calculated from the following Equation 2.

[0336]

[0337] [Equation 2]

[0338] Apparent density (g / cm³) 3 ) = (Electrode weight (g) / {(Electrode thickness (cm)) x (Electrode area (cm²)} 2 ))}

[0339]

[0340] Porosity (vol%) Example 1-229 Example 2-244 Example 3-245 Example 4-244 Example 5-246 Example 6-223 Comparative Example 2-215

[0341]

[0342] FIG. 7 is a free-standing film prepared to measure the ion conductivity of the protective layers according to Examples 1-2 to 5-2 and Comparative Example 2-2. Meanwhile, FIG. 8 shows the results of measuring the ion conductivity of the protective layers according to Examples 1-2 to 5-2 and Comparative Example 2-2. Referring to this, it was confirmed that the protective film of the Examples had higher electrolyte impregnation compared to Comparative Example 2-2, and accordingly, exhibited superior ion conductivity. Furthermore, Example 5-2, which had the highest content of porous particles, showed the best electrolyte impregnation and ion conductivity.

Claims

1. It includes a negative electrode active material layer and a protective layer disposed on the surface of the negative electrode active material layer, The above protective layer comprises porous particles and a polymer matrix in which the porous particles are dispersed, and The above porous particles comprise a vinyl polymer in which benzene rings are bonded to carbons of the main chain, have a hyper-crosslinked structure, and have one or more moiety A grafted to the main chain. The above moiety A is terminally substituted by a single ion-conducting functional group, and The above polymer matrix is ​​a cathode for an electrochemical device comprising a fluorine-based polymer.

2. A cathode for an electrochemical device, wherein the vinyl polymer comprises one or more units derived from a styrene derivative in its main chain, and the units derived from the styrene derivative comprise divinylbenzene, chloromethylstyrene, or both.

3. In Paragraph 1, The above moiety A is a cathode for an electrochemical device that is bonded to the benzene ring portion of the main chain.

4. In Paragraph 1, A cathode for an electrochemical device comprising the above single ion-conducting functional group represented by the following chemical formula 1: [Chemical Formula 1] R in Chemical Formula 1 above 1 It comprises fluorine (F), a perfluoroalkyl group having 1 to 6 carbon atoms, a perfluoroalkoxy group having 1 to 6 carbon atoms (C1-C6 perfluoroalkoxy), a fluoroalkyl group, a fluorosubstituted alkyl group, a trifluoromethyl group, or one or more of these, and * indicates a point where the functional group of Formula 1 is bonded to moiety A.

5. In Paragraph 4, R in Chemical Formula 1 above 1 A cathode for an electrochemical device comprising a perfluoroalkyl group having 1 to 6 carbon atoms, a perfluoroalkoxy group having 1 to 6 carbon atoms (C1-C6 perfluoroalkoxy), a fluoroalkyl group, a fluorosubstituted alkyl group, a trifluoromethyl group, or one or more of these, wherein a portion thereof is substituted with an atom other than fluorine.

6. A cathode for an electrochemical device according to claim 1, wherein the single ion-conducting functional group comprises a group represented by the following chemical formula 1a: [Chemical Formula 1a] In the above chemical formula 1a, * represents a point where the functional group of the above chemical formula 1 is attached to moiety A.

7. In Paragraph 1, The above moiety A is a cathode for an electrochemical device having a structure derived from a vinyl group terminally substituted with a single ion-conducting functional group.

8. In Paragraph 1, A cathode for an electrochemical device, wherein the above moiety A comprises one or more compounds derived from chemical formulas 2a to 2h below. [Chemical Formulas 2a to 2h] 9. In Paragraph 1, The above-mentioned styrene-based polymer having a hyper-crosslinked structure is a compound represented by Chemical Formula 3 below, and is a cathode for an electrochemical device. [Chemical Formula 3] In the above chemical formula 3, n, m, l, and k are each independently integers greater than or equal to 1, and At least two units are benzene rings bonded to each other, or at least one unit is grafted with a polystyrene chain.

10. In Paragraph 1, The above-mentioned fluorine-based polymer is a cathode for an electrochemical device comprising polyvinylidene fluoride.

11. In Paragraph 1, The above-mentioned negative electrode active material layer comprises lithium metal, an alloy of lithium and a heterogeneous metal, or both, for a negative electrode for an electrochemical device.

12. In Paragraph 11, The above-mentioned heterogeneous metal is a cathode for an electrochemical device comprising aluminum (Al), magnesium (Mg), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), tin (Sn), or two or more of these.

13. In Paragraph 1, The above protective layer is a cathode for an electrochemical device having a thickness of 0.1 μm to 10 μm.

14. In Paragraph 1, A cathode for an electrochemical device in which the protective layer comprises 30 wt% to 95 wt% of a fluorine-based polymer relative to 100 wt% of the protective layer.

15. In Paragraph 1, The above protective layer is a cathode for an electrochemical device having a porosity of 20 vol% to 80 vol%.

16. In Paragraph 1, The above porous particle is a cathode for an electrochemical device composed of a core portion having a porous structure and a shell portion having a brush structure grafted onto the core portion.

17. Includes an anode, a cathode, and an electrolyte, The above anode includes sulfur (S8), a sulfur-based compound, or both as an anode active material, and The above-mentioned negative electrode is a lithium-sulfur secondary battery according to any one of claims 1 to 16.

18. In Paragraph 17, A lithium-sulfur secondary battery in which the above sulfur (S8) and / or sulfur-based compound is included in the positive active material in the form of a sulfur-carbon composite combined with a porous carbon material.

Images