Electrode for lithium sulfur battery and high energy density lithium sulfur battery comprising same

Abstract

The present invention relates to an electrode for a lithium sulfur battery, the electrode being for improving energy density, and comprising a current collector and an electrode active material layer disposed on at least one surface of the current collector, wherein the electrode active material layer contains a sulfur-carbon composite and a binder, the sulfur-carbon composite includes a porous carbon material and a sulfur-based material, and the current collector includes aluminum (Al) and has a thickness of about 9 µm or less.

Description

Electrode for lithium sulfur battery and high energy density lithium sulfur battery containing same

[0001] The present invention relates to an electrode for a lithium sulfur battery and a lithium sulfur battery including the same.

[0002] This application claims priority to Korean Patent Application No. 10-2023-0167317, filed with the Korean Intellectual Property Office on November 27, 2023, the entire disclosure of which is incorporated herein by reference.

[0003] As the scope of application of lithium secondary batteries expands beyond portable electronic devices to include electric vehicles (EVs) and energy storage systems (ESSs), the demand for lithium secondary batteries with high capacity, high energy density, and long lifespan is increasing.

[0004] Among various lithium secondary batteries, the lithium-sulfur battery is a battery system that uses a sulfur-based material containing a sulfur-sulfur bond as a positive electrode active material, and lithium metal, a carbon-based material in which lithium ions can be inserted / deinserted, or silicon or tin that forms an alloy with lithium as a negative electrode active material.

[0005] Sulfur, the main material of the cathode active material in lithium-sulfur batteries, has the advantages of being a low atomic weight, abundant in resources, easy to supply, inexpensive, non-toxic, and environmentally friendly material.

[0006] The present invention

[0007] An object of the present invention is to provide an electrode for implementing a high-energy-density lithium-sulfur battery and a lithium-sulfur battery including the same.

[0008] In one aspect, the present invention aims to provide an electrode capable of reducing the weight of the electrode, thereby increasing the proportion of the active material relative to the total weight of the electrode, and lowering the weight ratio of the current collector.

[0009] In one aspect, the present invention seeks to provide an electrode capable of increasing the proportion of active material relative to the total weight of the electrode even if the electrode has a low loading.

[0010] In one aspect, the present invention seeks to provide a lithium sulfur battery that realizes high energy density by having a high proportion of active material relative to the total weight of the electrode.

[0011] According to one aspect of the present invention, electrodes of the following embodiments are provided.

[0012] The electrode according to the first embodiment is:

[0013] An electrode comprising a current collector and an electrode active material layer positioned on at least one side of the current collector,

[0014] The electrode active material layer includes a sulfur-carbon composite and a binder, the sulfur-carbon composite includes a porous carbon material and a sulfur-based material, and the current collector includes aluminum (Al) and has a thickness of about 9 ㎛ or less.

[0015] According to the second embodiment, in the first embodiment,

[0016] The above electrode has a value of 90 cm according to the following equation 1. 2 / mAh or more can be satisfied.

[0017] [Formula 1]

[0018]

[0019] In the above equation 1,

[0020] The unit of weight of the electrode and the weight of the current collector is grams (g).

[0021] The loading amount of the electrode is the loading amount of sulfur in the electrode, and the unit is mAh / cm 2 am.

[0022] According to the third embodiment, in the first embodiment or the second embodiment,

[0023] The value according to the above formula 1 is 100 to 150 cm 2 / mAh can be satisfied.

[0024] According to the fourth embodiment, in any one of the first to third embodiments,

[0025] The thickness of the above-mentioned collector may be 5 ㎛ to 9 ㎛.

[0026] According to the fifth embodiment, in any one of the first to fourth embodiments,

[0027] The content of the sulfur-based material in the electrode active material layer may be 65 wt% or more.

[0028] According to the sixth embodiment, in any one of the first to fifth embodiments,

[0029] The sulfur loading is 5 mAh / cm 2 It could be as follows:

[0030] According to the seventh embodiment, in any one of the first to sixth embodiments,

[0031] The sulfur loading is 3.5 mAh / cm 2 It could be as follows:

[0032]

[0033] According to another aspect of the present invention, lithium sulfur batteries of the following embodiments are provided.

[0034] A lithium sulfur battery according to the 8th embodiment,

[0035] It comprises a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte,

[0036] At least one of the positive and negative electrodes may be an electrode according to any one of the first to seventh embodiments.

[0037] According to the ninth embodiment, in the eighth embodiment,

[0038] The weight ratio of the electrolyte and sulfur (El / S) may be 3.5 g / g or less.

[0039] According to the tenth embodiment, in the eighth or ninth embodiment,

[0040] The energy density of the above lithium sulfur battery may be 350 Wh / kg or more.

[0041] According to one aspect of the present invention, there is an advantage of increasing the weight ratio of the active material to the total weight of the electrode.

[0042] In addition, in a low-loading electrode of active material, it can show the advantage of increasing the energy density of a battery using it by increasing the weight ratio of the active material to the total weight of the electrode.

[0043] In addition, according to one aspect of the present invention, the weight ratio of the current collector to the total weight of the electrode is low, so that a lithium sulfur battery with high energy density can be realized.

[0044] Figure 1 is a graph showing the weight ratio of the current collector in a pouch-type battery according to the thickness of the current collector (Al foil) of Comparative Examples 1 to 6 and Examples 1 to 4.

[0045] Figure 2 is a graph showing the relative energy density values ​​of the batteries according to the thickness of the current collector (Al foil) of Comparative Examples 1 to 6 and Examples 1 to 4.

[0046] Hereinafter, the present invention will be described with examples.

[0047] 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 spirit 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 possible manner.

[0048] Throughout this specification, whenever a part is said to “include” or “have” a component, this does not mean that other components are excluded, but rather that other components may be included, unless otherwise specifically stated.

[0049] In addition, the terms "about", "substantially", etc. used throughout this specification are used in the sense of numerical values ​​or near numerical values ​​when manufacturing and material tolerances inherent to the meanings stated are presented, and are used to prevent unscrupulous infringers from unfairly exploiting disclosures that mention exact or absolute values ​​to aid understanding of this specification.

[0050] Throughout this specification, the description of “A and / or B” means “A or B or both.”

[0051] In the present invention, the “specific surface area” is measured by the BET method, and can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77 K) using, for example, BELSORP-mini II of BEL Japan.

[0052] The term "(poly)sulfide" as used herein means "(poly)sulfide ion (Sx 2- , 1 ≤ x ≤ 8)" and "lithium (poly)sulfide (Li2S x or LiS x - , 1 ≤ x ≤ 8)" is a concept that includes all of them.

[0053] The term "polysulfide" as used herein means "polysulfide ion (Sx 2- , 1 < x ≤ 8)" and "lithium polysulfide (Li2S x or LiS x - , 1 < x ≤ 8)" is a concept that includes all of them.

[0054] The term "composite" used in this specification refers to a material in which two or more materials are combined to form physically and chemically different phases and exhibit more effective functions.

[0055] The term "porosity" used in this specification means the ratio of the volume occupied by pores to the total volume of a structure, and uses vol% as its unit, and can be used interchangeably with terms such as void ratio and porosity.

[0056] Unless otherwise specified in this specification, the porosity may have a value obtained by measuring the apparent density of the target material and using the actual density calculated based on the actual density and composition of the components constituting the target material, using the following relationship.

[0057] Porosity (vol%) = {1 - (apparent density / actual density)} x 100

[0058] In the present invention, "particle diameter D 10 " means the particle size based on 10% of the volume cumulative particle size distribution of the target particle, and " particle diameter D 50 " means the particle size at 50% of the volume cumulative particle size distribution of the target particle, and " particle diameter D 90 " refers to the particle size at 90% of the volume cumulative particle size distribution of the target particle.

[0059] Above diameter D 10 , D 50 and D 90Each can be measured using a laser diffraction method. For example, after dispersing the target particle powder in a dispersion medium, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz with an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then finding the particle sizes corresponding to 10%, 50%, and 90% of the volume cumulative distribution, respectively.

[0060] The present invention relates to an electrode for an electrochemical device and an electrochemical device, for example, a secondary battery, comprising the electrode. The secondary battery may be a lithium secondary battery. The electrode according to the present invention may be at least one of a positive electrode and a negative electrode, and may be, for example, a positive electrode comprising sulfur as an active material. In addition, the electrode may comprise a sulfur-based material as an active material, and the lithium secondary battery comprising such an electrode may be a lithium-sulfur secondary battery (or lithium sulfur battery).

[0061] Lithium-sulfur batteries are a conversion reaction between lithium ions and sulfur at the cathode (S8+ 16Li + + 16e - -> The theoretical specific capacity from 8Li2S reaches 1,675 mAh / g, and when lithium metal is used as the negative electrode, it shows a theoretical energy density of 2,600 Wh / kg. This is a very high number compared to the theoretical energy density of other battery systems currently being studied (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) and lithium ion batteries (250 Wh / kg), and therefore, it is attracting attention as a high-capacity, eco-friendly, and low-cost lithium secondary battery among the secondary batteries being developed so far.

[0062] However, due to issues such as the large amount of electrolyte, decreased anode efficiency, and cathode degradation, the theoretical capacity cannot be fully realized, preventing sufficiently high energy density. Accordingly, research is ongoing to develop lithium-sulfur batteries with high energy density.

[0063] Since the density of the sulfur-carbon complex used in the positive electrode of a lithium-sulfur battery is low, when the current collector is coated with the sulfur-carbon complex, the density of the current collector becomes relatively high, so the weight ratio of the current collector to the total electrode weight increases. Therefore, the weight ratio of the current collector to the electrode is relatively high, making it difficult to implement a high-energy-density battery (e.g., a pouch-type battery). In addition, when implementing a low-loading electrode by lowering the loading amount for various purposes, such as increasing the surface utilization of carbon in the positive electrode and thus increasing the electrochemical reaction rate, the ratio of the active material in the electrode is reduced, making it difficult to implement a high-energy-density battery likewise.

[0064] According to one embodiment of the present invention, an electrode is provided that can reduce the weight of the electrode, thereby increasing the proportion of an active material relative to the total weight of the electrode and lowering the weight ratio of a current collector.

[0065]

[0066] Electrode

[0067] According to one aspect of the present invention, an electrode comprises:

[0068] An electrode comprising a current collector and an electrode active material layer positioned on at least one side of the current collector, wherein the electrode active material layer comprises a sulfur-carbon composite and a binder.

[0069] According to one aspect of the present invention, the sulfur-carbon composite includes a porous carbon material and a sulfur-based material.

[0070] According to one aspect of the present invention, the thickness of the entire body is about 9 ㎛ or less.

[0071]

[0072] sulfur-carbon complex

[0073] According to one embodiment of the present invention, the electrode may be characterized in that the thickness of the current collector is relatively thin compared to a conventional electrode that uses a sulfur-carbon composite as an active material, in which a sulfur-based material is supported on a porous carbon material, thereby implementing an electrode that can be used in an electrochemical device having a high energy density.

[0074] For example, in one embodiment of the present invention, the sulfur-carbon composite may include an active material of the positive electrode, and may be bound by the binder to form an electrode active material layer. The sulfur-carbon composite includes a porous carbon material and a sulfur-based material.

[0075] In one embodiment of the present invention, the sulfur-based material is included as an active material in an electrochemical device, for example, a secondary battery, a lithium secondary battery, a lithium sulfur battery, etc., and can be used as a sulfur-based material without limitation as long as it is used as an active material in a lithium sulfur battery. For example, the sulfur-based material may be inorganic sulfur (S8), lithium (poly)sulfide (Li2S). x or LiS x - , 1 ≤ x ≤ 8), an organic sulfur compound, a carbon-sulfur polymer, or a mixture of two or more thereof. In one embodiment of the present invention, the organic sulfur compound may be, for example, 2,5-dimercapto-1,3,4-thiadiazole, 1,3,5-trithiocyanuic acid, or a mixture thereof, but is not limited thereto. In one embodiment of the present invention, the carbon-sulfur polymer may be a carbon-sulfur polymer represented by the chemical formula (C2S x ) n(x=2.5 to 50, n≥2) can be given as an example, but the present invention is not limited thereto.

[0076] In one embodiment of the present invention, the porous carbon material may be any carbon material with a porous structure and electrical conductivity for supporting the sulfur-based material in order to improve the electrical conductivity of the electrode active material layer while using the sulfur-based material having no or very low electrical conductivity in the electrode active material layer, without limitation. For example, the porous carbon material may be carbon nanotubes, carbon black, graphite, activated carbon, graphene, or a mixture of two or more thereof, but the present invention is not limited thereto.

[0077] For example, the sulfur-carbon composite may have a structure in which the sulfur-based material is supported on the outer surface and / or the inner surface of the pores of the porous carbon material, but is not limited thereto.

[0078] In one embodiment of the present invention, the sulfur-based material in the sulfur-carbon composite may be included by physical adsorption with the porous carbon material, or by chemical bonding such as covalent bonding or van der Waals forces between sulfur element (S) and carbon in the porous carbon material. In particular, the sulfur-based material may be chemically bonded to the surface of the porous carbon material to form a composite.

[0079] In one embodiment of the present invention, the sulfur-carbon composite may be a composite formed by simply mixing the sulfur-based material and the carbon material, or may have a core-shell structured coating form or a supported form. The core-shell structured coating form is one in which either the sulfur-based material or the carbon material coats another material, for example, the surface of the carbon material may be wrapped with sulfur, or vice versa. In addition, the supported form may be a form in which the sulfur-based material is filled inside the carbon material, particularly in the internal pores. Any form of the sulfur-carbon composite may be used as long as it satisfies the content ratio of the sulfur and carbon material presented above, and is not limited thereto in the present invention.

[0080] In one embodiment of the present invention, the sulfur-carbon complex may have a content of elemental sulfur (S) of about 60 wt% or more, 70 wt% or more, or 75 wt% or more, and 99 wt% or less, relative to 100 wt% of the sulfur-carbon complex. For example, the sulfur-carbon complex may have a content of elemental sulfur (S) of about 60 wt% to 99 wt%, 70 wt% to 99 wt%, 60 wt% to 90 wt%, 75 wt% to 90 wt%, 70 wt% to 85 wt%, 70 wt% to 80 wt%, 75 wt% to 80 wt%, or 70 wt% to 75 wt%, relative to 100 wt% of the sulfur-carbon complex.

[0081] In the sulfur-carbon composite according to the present invention, the sulfur-based material is located on at least one of the outer surface and the inner surface of the pores of the porous carbon material, and at this time, it may be present in an area of ​​less than 100% of the entire inner and outer surface of the porous carbon material, for example, about 1% to 95%, or about 60% to 90%. When the sulfur is present on the surface of the porous carbon material within the above range, it can exhibit the maximum effect in terms of electron transfer area and electrolyte wettability. For example, since the sulfur is thinly and evenly impregnated on the surface of the porous carbon material in the above range, the electron transfer contact area can be increased during the charge and discharge process. If the sulfur is located in an area of ​​100% of the entire surface of the porous carbon material, the porous carbon material is completely covered with sulfur, so that the wettability of the electrolyte is reduced and the contact with the conductive material included in the electrode is reduced, so that electron transfer is not received and the reaction cannot be participated in.

[0082] Next, an example of a method for manufacturing the above sulfur-carbon composite will be described. The method for manufacturing the sulfur-carbon composite according to the present invention can be manufactured by a compounding method comprising the steps of (S1) mixing a porous carbon material and a sulfur-based material, and then (S2) compounding.

[0083] The mixing in step (S1) is intended to increase the degree of mixing between the sulfur-based material and the porous carbon material, and may be performed using a stirring device according to one embodiment. At this time, the mixing time and speed may also be selectively adjusted depending on the content and conditions of the raw materials.

[0084] The compounding method of the above (S2) step is not particularly limited in the present invention, and for example, a wet compounding method such as dry compounding or spray coating can be used. For example, a method can be used in which the mixture of sulfur and carbon material obtained after mixing is pulverized by ball milling and then placed in an oven at about 120°C to 160°C for about 20 minutes to 1 hour so that the molten sulfur can evenly coat the inner and outer surfaces of the carbon material.

[0085] The sulfur-carbon composite manufactured through the above-described manufacturing method has a structure in which the specific surface area is high, the sulfur loading amount is high, and the sulfur utilization rate is improved, so that not only the electrochemical reactivity of sulfur is improved, but also the accessibility and contactability of the electrolyte are improved, thereby improving the capacity and life characteristics of the lithium-sulfur battery.

[0086] In one embodiment of the present invention, the sulfur-carbon complex is about 1.5 g / cm 3 It may have a density of about 1.5 g / cm. For example, the sulfur-carbon complex may have a density of about 1.5 g / cm. 3 3.0 g / cm 3 may have a density of about 1.8 g / cm. Alternatively, the sulfur-carbon complex may have a density of about 1.8 g / cm. 3 2.5 g / cm 3 , about 1.8 g / cm 3 2.1 g / cm 3 , or about 1.9 g / cm 3 2.1 g / cm 3 , for example, about 2.0 g / cm 3 It may have a density of .

[0087]

[0088] Electrode thickness and equation 1

[0089] An electrode comprising a sulfur-based material as an active material may be configured by forming an electrode active material layer using a sulfur-based material, a conductive material, a binder, etc. That is, an electrode having a high density of the electrode active material layer may be implemented by including the sulfur-based material structurally independently from the conductive material. In the present invention, the sulfur-based material is supported on a porous carbon material and used as an active material as a sulfur-carbon composite, so the density of the electrode active material layer may be implemented to be lower than that of an electrode in which the sulfur-based material is included structurally independently from the conductive material.

[0090] Accordingly, the present invention is to provide an electrode in which the weight ratio of the current collector is relatively reduced in order to increase the density of the electrode active material layer, for example, the density of the sulfur-carbon complex in the electrode, by using the above-described sulfur-carbon complex and binding it with a binder to form an electrode active material layer.

[0091] For this purpose, the thickness of the entire collector may be limited to about 9 ㎛ or less, but the reason for limiting the thickness of the entire collector in this way is not limited to this.

[0092] For example, in one embodiment of the present invention, the electrode active material layer may have a porosity of about 60 vol% to 85 vol%. For example, the porosity of the electrode active material layer may be about 60 vol% to 80 vol%, 65 vol% to 80 vol%, 70 vol% to 80 vol%, or 75 vol% to 80 vol, for example, about 78 vol%.

[0093] In this specification, the term "porosity" refers to the ratio of the volume occupied by pores to the total volume of a structure, and uses vol% as its unit, and can be used interchangeably with terms such as porosity and porosity. The porosity can be measured according to the method of ISO 15901:2019 known in the art.

[0094] In one embodiment of the present invention, the porosity of the electrode active material layer can be measured, for example, by a mercury penetrant method (Hg porosimeter), and can be measured, for example, using a mercury porosimeter (Micromeritics AUTOPORE V). In addition, the porosity of the positive electrode active material layer can be measured using a BET (Brunauer-Emmett-Teller) measurement method using an adsorbed gas such as nitrogen, and can be measured, for example, using an analyzer of the BELSORP series of BEL Japan, such as mini II, but the present invention is not limited thereto. The porosity measured by this method can mean the total volume of pores formed in the positive electrode active material layer. In addition, the porosity can be measured by calculating from the true density of the materials constituting the positive electrode active material layer, the apparent density of the manufactured positive electrode active material layer, and the thickness of the positive electrode. For example, the porosity can be calculated as a value of [(true density - apparent density) / true density] X 100(%) of the positive electrode active material layer.

[0095] An electrode according to one embodiment of the present invention has a value of 90 cm according to the following formula 1. 2 / It may satisfy more than mAh.

[0096] [Formula 1]

[0097]

[0098] In the above equation 1,

[0099] The unit of weight of the electrode and the weight of the current collector is grams (g).

[0100] The loading amount of the electrode is the loading amount of sulfur in the electrode, and the unit is mAh / cm 2 am.

[0101]

[0102] In one embodiment of the present invention, since the current collector does not affect the capacity expression of the electrode, the lower the weight ratio of the current collector based on the total weight of the electrode, that is, the higher the weight ratio of the component (e.g., electrode active material layer) excluding the current collector from the total weight of the electrode, the more advantageous the implementation of high energy density can be.

[0103] In one embodiment of the present invention, the 'loading amount of the electrode' is the amount of active material per unit area of ​​the electrode, for example, converted to the capacity value of the electrode per unit area of ​​the electrode, mAh / cm 2 It can be expressed as a value of . At this time, as the loading amount of the electrode increases, the content of the active material in the electrode increases, and accordingly, the total weight of the electrode may increase. Therefore, the weight increase due to loading can be corrected by dividing by the loading amount value of the electrode in Equation 1.

[0104] Therefore, a higher value according to the above equation 1 may indicate an electrode suitable for use in an electrochemical device having a high energy density.

[0105] For example, according to one embodiment of the present invention, the value according to the above formula 1 is about 90 cm 2 An electrode may be provided that exhibits more than / mAh. For example, a value according to the above formula 1 may be about 90 cm 2 / mAh to 200 cm 2 / mAh, 90 cm 2 / mAh to 180 cm 2 / mAh, 90 cm 2 / mAh to 160 cm 2 / mAh or 90 cm 2 / mAh to 150 cm 2 / mAh electrodes may be provided. In one embodiment, the value according to the above formula 1 is 95 cm 2 / mAh to 150 cm 2 / mAh, 100 cm 2 / mAh to 145 cm2 / mAh or 105.5 cm 2 / mAh to 142.5 cm 2 An electrode having a capacity of / mAh may be provided. When the electrode has the value of the above-described formula 1, it may exhibit a beneficial effect in implementing an electrode and electrochemical device having a high energy density, but the present invention is not limited thereto.

[0106] For the above-described reason, the thinner the current collector is, the more advantageous it is for implementing high energy of the electrode. According to one embodiment of the present invention, the thickness of the current collector may be, for example, about 9 ㎛ or less, for example, about 1 ㎛ to 9 ㎛, 2 ㎛ to 9 ㎛, 3 ㎛ to 8.5 ㎛, 4 ㎛ to 8.5 ㎛, 5 ㎛ to 8.5 ㎛, 5.5 ㎛ to 8.5 ㎛, 6 ㎛ to 8 ㎛, 5.5 ㎛ to 7 ㎛, or 5.5 ㎛ to 6.5 ㎛. When the thickness of the current collector is in the above-described range, it is possible to implement a high energy density without significantly increasing the weight of the electrode relative to its capacity, and may also exhibit an advantageous effect in terms of preventing the problem of the current collector being torn or damaged, but the present invention is not limited thereto.

[0107] In one embodiment of the present invention, the "thickness" of the current collector may be measured using a known thickness value of the current collector being used, or may be a value measured using a known thickness measuring device. The thickness measuring device may be, for example, a thickness measuring device manufactured by Mitutoyo Corporation. Alternatively, the thickness of the current collector may be measured using an electron microscope photograph of the electrode cross-section.

[0108] As described above, in one embodiment of the present invention, if the electrode loading amount is too high, even if the thickness of the current collector is within the above-described range, a phenomenon may occur in which the energy density of the battery is not significantly improved. To this end, in one embodiment of the present invention, when the electrode loading amount is below a certain level, a current collector having the above-described thickness may be used.

[0109] In one embodiment of the present invention, the loading amount of the electrode is, for example, about 10 mAh / cm 2 It may be less than or equal to. For example, the loading amount of the electrode is about 0.5 mAh / cm 2 10 mAh / cm 2 It could be.

[0110] In another embodiment of the present invention, the loading amount of the electrode is, for example, about 9 mAh / cm 2 Below, 8 mAh / cm 2 Below, 7 mAh / cm 2 Below, 6 mAh / cm 2 Less than or equal to 5 mAh / cm 2 It may be less than or equal to. Alternatively, the loading amount of the electrode may be, for example, about 4.5 mAh / cm 2 Below, 4.0 mAh / cm 2 Less than or equal to 3.5 mAh / cm 2 It could be as follows:

[0111] In another embodiment of the present invention, the loading amount of the electrode is, for example, about 1 mAh / cm 2 5 mAh / cm 2 , 1.5 mAh / cm 2 5 mAh / cm 2 , 2 mAh / cm 2 5 mAh / cm 2 , 2.1 mAh / cm 2 5 mAh / cm 2 , 2.2 mAh / cm 2 5 mAh / cm 2, 2.3 mAh / cm 2 5 mAh / cm 2 or 2.3 mAh / cm 2 5.0 mAh / cm 2 , 2.3 mAh / cm 2 4.5 mAh / cm 2 , 2.3 mAh / cm 2 4.0 mAh / cm 2 , 2.3 mAh / cm 2 3.5 mAh / cm 2 It could be.

[0112] In one embodiment of the present invention, the 'loading amount of the electrode' indicates the loading amount of sulfur (S) in the electrode, and may be measured according to a known method for measuring the loading amount of sulfur in the electrode. For example, the loading amount of the electrode may be a value calculated from the total weight of sulfur (S) included as an electrode active material in the electrode. At this time, the weight of sulfur in the electrode may be measured from the amount of the electrode active material input during the manufacturing step, and may be measured through thermogravimetric analysis (TGA) of the electrode after manufacturing. Meanwhile, when obtaining an electrode by disassembling a manufactured lithium-sulfur battery, the charged lithium-sulfur battery is disassembled under an inert atmosphere to obtain an electrode, and then the electrode is washed and dried using an appropriate washing solvent, and the electrode active material layer is scraped off. The resultant product may be subjected to thermogravimetric analysis (TGA) to measure the content of sulfur (S) derived from the active material, and the calculation may be performed, but the measuring method is not limited thereto. At this time, the actual capacity of sulfur (1,200 mAh / g) was calculated from the weight of sulfur obtained above. s ) can be used to calculate the sulfur loading amount.

[0113]

[0114] Electrode active material layer

[0115] In one embodiment of the present invention, the electrode may be an electrode containing a high content of active material, to solve the problem of the increase in energy density being disproportional to the increase in electrode density.

[0116] For example, the electrode may have a sulfur-based material content of about 65 wt% or more in the electrode active material layer. For example, the sulfur-based material content in the electrode active material layer may be about 65 wt% to 99 wt%, 65 wt% to 95 wt%, 65 wt% to 90 wt%, 65 wt% to 85 wt%, 70 wt% to 85 wt%, 70 wt% to 80 wt%, 70 wt% to 75 wt%, 72.5 wt% to 75 wt%, or 70 wt% to 72.5 wt%, but the present invention is not limited thereto. In the present invention, when the content of the sulfur-based material in the electrode active material layer is within the above-described range, there may be an advantageous effect of increasing the capacity of the active material in the electrode while maintaining the content of the conductive carbon material and the content of the binder at a certain level to realize high electrical conductivity and / or excellent bonding strength between the active materials, but the present invention is not limited thereto.

[0117] In one embodiment of the present invention, the content of the sulfur-based material in the electrode active material layer may be calculated from the weight of the sulfur-based material introduced in the manufacturing step of the electrode active material layer based on the total weight of the electrode material introduced. Alternatively, the content of the sulfur-based material may be calculated from the analyzed value of the total weight of the electrode active material layer, excluding the weight of the current collector in the electrode, based on the manufactured electrode. In this case, the method for analyzing the content of the sulfur-based material in the electrode active material layer may refer to the method for measuring the loading amount described above.

[0118]

[0119] Whole house

[0120] According to one aspect of the present invention, the entire body comprises aluminum (Al).

[0121] For example, in one embodiment of the present invention, the current collector may be a current collector that can be used for the positive electrode and may include aluminum.

[0122] In another embodiment of the present invention, the collector may be made only of aluminum (Al).

[0123] In another embodiment of the present invention, the current collector may include aluminum and further include a current collector component used in the positive electrode. For example, the current collector may include aluminum, stainless steel, nickel, titanium, calcined carbon, silver, or two or more of these components.

[0124] In one embodiment of the present invention, when the collector further includes a component other than aluminum, for example, a component in which stainless steel is laminated on the surface of aluminum, aluminum is laminated on the surface of stainless steel, or aluminum is surface-treated with nickel, titanium, carbon, silver, or two or more of these components may be used.

[0125] In one embodiment of the present invention, in order to improve the bonding strength with the electrode active material layer formed on the surface of the current collector, fine irregularities may be formed on the surface of the current collector, but the present invention is not limited thereto.

[0126] In one embodiment of the present invention, the current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc., and for example, the current collector may be aluminum foil.

[0127]

[0128] Hereinafter, other components of the electrode according to one aspect of the present invention will be described in detail.

[0129] In one embodiment of the present invention, the binder serves to improve adhesion between active material particles and adhesion between the active material and the current collector, and examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The above binder resin may be included in an amount of about 1 wt% to 30 wt%, for example, 1 wt% to 20 wt%, or 1 wt% to 10 wt%, based on the total weight of the positive electrode active material layer.

[0130] In one embodiment of the present invention, the electrode active material layer may further include other additives such as a conductive agent in addition to the sulfur-carbon composite and the binder.

[0131] The conductive material is used, for example, to provide conductivity to the electrode, and can be used without any particular limitation as long as it does not cause a chemical change in the battery to be formed and has electronic conductivity. Examples thereof include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, and carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. When the conductive material is used, the conductive material may typically be included in an amount of about 1 wt% to 30 wt%, for example, 1 wt% to 20 wt%, or 1 wt% to 10 wt%, based on the total weight of the positive electrode active material layer.

[0132] In one embodiment of the present invention, the electrode active material layer may further include other active materials in addition to the above-described sulfur-carbon composite.

[0133] At this time, other active materials that may be further included may not be particularly limited, for example, if they can be used as active materials in lithium secondary batteries. Such active materials may include, for example, lithium transition metal oxide; lithium metal iron phosphate; lithium nickel-manganese-cobalt oxide; lithium nickel-manganese-cobalt oxide, an oxide in which some of the nickel-manganese-cobalt oxide is substituted with another transition metal; or two or more thereof, but are not limited thereto. For example, the positive electrode active material may include, for example, a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; a compound having the chemical formula Li 1+x Mn 2-xLithium manganese oxides such as O4 (where x is 0 to 0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, LiV3O4, V2O5, Cu2V2O7; chemical formula LiNi 1-x M x Ni-site type lithium nickel oxide represented by O2 (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); chemical formula LiMn 2-x M x Lithium manganese composite oxides represented by O2 (wherein M = Co, Ni, Fe, Cr, Zn or Ta and x = 0.01 to 0.1) or Li2Mn3MO8 (wherein M = Fe, Co, Ni, Cu or Zn); lithium metal phosphate LiMPO4 (wherein M = Fe, CO, Ni or Mn); lithium nickel-manganese-cobalt oxide Li 1+x (Ni a Co b Mn c ) 1-x O2(x = 0 ~ 0.03, a = 0.3 ~ 0.95, b = 0.01 ~ 0.35, c = 0.01 ~ 0.5, a+b+c=1); Lithium nickel-manganese-cobalt oxide partially substituted with aluminum a [Ni b Co c Mn d Al e ] 1-f M1 f O2 (M1 is at least one selected from the group consisting of Zr, B, W, Mg, Ce, Hf, Ta, La, Ti, Sr, Ba, F, P and S, and 0.8≤a≤1.2, 0.5≤b≤0.99, 0 <c<0.5, 0<d<0.5, 0.01≤e≤0.1, 0≤f≤0.1); 리튬 니켈-망간-코발트 산화물에 일부가 다른 전이금속으로 치환된 산화물 Li 1+x (Ni a Cob Mn c M d ) 1-x O2(x = 0 ~ 0.03, a = 0.3 ~ 0.95, b = 0.01 ~ 0.35, c = 0.01 ~ 0.5, d = 0.001 ~ 0.03, a+b+c+d=1, M is any one selected from the group consisting of Fe, V, Cr, Ti, W, Ta, Mg and Mo), disulfide compounds; Fe2(MoO4)3, etc., but are not limited thereto.

[0134]

[0135] Lithium sulfur battery

[0136] According to another aspect of the present invention, a lithium sulfur battery comprises:

[0137] It comprises an anode, a cathode, a separator interposed between the anode and the cathode, and an electrolyte, and at least one of the anode and the cathode is the above-described electrode.

[0138] In one embodiment of the present invention, the positive electrode of the lithium sulfur battery may be the electrode described above. For example, the positive electrode may be an electrode including a current collector and an electrode active material layer positioned on at least one side of the current collector, wherein the electrode active material layer includes a sulfur-carbon composite and a binder, the sulfur-carbon composite includes a porous carbon material and a sulfur-based material, and the current collector includes aluminum (Al) and may have a thickness of about 9 μm or less.

[0139] In one embodiment of the present invention, the unit structure of the positive electrode / separator / cathode may be referred to as an electrode assembly, and the electrode assembly may be formed by, for example, stacking the separator between the negative electrode and the positive electrode to form a stacked or stacked / folded structure, or may be wound to form a jellyroll structure. In addition, when the jellyroll structure is formed, a separator may be additionally arranged on the outside to prevent the negative electrode and the positive electrode from coming into contact with each other.

[0140] In one embodiment of the present invention, when the anode is the electrode described above, the cathode is described in detail.

[0141] The above negative electrode may have a structure in which a negative electrode active material layer is formed on one or both sides of a long sheet-shaped negative electrode collector, and the negative electrode active material layer may include a negative electrode active material and a binder resin. In addition, the negative electrode active material layer may further include a conductive material as needed.

[0142] For example, the negative electrode can be manufactured by applying a negative electrode slurry prepared by dispersing a negative electrode active material, a conductive material, and a binder in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water to one or both sides of a long sheet-shaped negative electrode collector, removing the solvent of the negative electrode slurry through a drying process, and then rolling. Meanwhile, an negative electrode including a non-coated region can be manufactured by not applying the negative electrode slurry to a part of the negative electrode collector, for example, one end of the negative electrode collector, when applying the negative electrode slurry.

[0143] The above negative active material is lithium (Li) + ) can be reversibly intercalated or deintercalated, a material that can reversibly form a lithium-containing compound by reacting with lithium ions, lithium metal or a lithium alloy. The material that can reversibly intercalate or deintercalate lithium ions can be, for example, crystalline carbon, amorphous carbon or a mixture thereof, and examples thereof include, but are not limited to, artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, soft carbon, hard carbon, etc.

[0144] The material capable of reversibly forming a lithium-containing compound by reacting with the lithium ions may be, for example, tin oxide, titanium nitrate, or a silicon-based compound.

[0145] The lithium alloy may be, for example, an alloy of a metal selected from the group consisting of lithium (Li) and sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn). For example, the negative electrode active material may be lithium metal, and may be in the form of, for example, a lithium metal thin film or lithium metal powder.

[0146] The above silicon compound is Si, Si-Me alloy (wherein Me is at least one selected from the group consisting of Al, Sn, Mg, Cu, Fe, Pb, Zn, Mn, Cr, Ti, and Ni), SiO y (Here, 0 <y<2), Si-C 복합체 또는 이들의 조합일 수 있으며, 예를 들면 SiO y (Here, 0 <y<2)일 수 있다. 실리콘계 화합물은 높은 이론 용량을 가지기 때문에 실리콘계 화합물을 음극 활물질로서 포함할 경우, 용량 특성을 향상시킬 수 있다.

[0147] As the negative electrode current collector, for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. The negative electrode current collector can typically have a thickness of about 3 µm to 500 µm, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0148] The above binder serves to improve adhesion between negative electrode active material particles and adhesion between the negative electrode active material and the negative electrode current collector. Examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The above binder may be included in an amount of about 1 wt% to 30 wt%, for example, 1 wt% to 20 wt%, or 1 wt% to 10 wt%, based on the total weight of the negative electrode active material layer.

[0149] The conductive material included as needed is used to provide conductivity to the negative electrode, and can be used without special restrictions as long as it does not cause chemical changes in the battery to be constructed and has electronic conductivity. Examples thereof include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, and carbon nanotube; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One of these may be used alone or a mixture of two or more may be used. When the conductive material is used, the conductive material may typically be included in an amount of about 1 wt% to 30 wt%, for example, about 1 wt% to 20 wt%, or 1 wt% to 10 wt%, based on the total weight of the negative electrode active material layer.

[0150] The separator is disposed within the electrode assembly in such a way that it is interposed between the negative electrode and the positive electrode. The separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used as a separator in lithium secondary batteries may be used without particular limitations. For example, the separator may be a porous polymer film, such as a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may also be used. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength.

[0151] In one embodiment of the present invention, the lithium sulfur battery may be provided in a form in which an electrode assembly comprising, for example, the positive electrode, negative electrode, and separator as constituent units is housed together with an electrolyte in a battery case.

[0152] In one embodiment of the present invention, the battery case may be selected without any particular limitation as long as it is a type commonly used in the field of technology, such as a pouch type, a metal can type, a cylindrical type, a stack type, or a coin type.

[0153] In one embodiment of the present invention, the lithium-sulfur battery may be a pouch-type, coin-type, or cylindrical battery, and may be, for example, a pouch-type battery, but the present invention is not limited thereto.

[0154] In one embodiment of the present invention, the electrolyte may be, for example, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc., and the type thereof is not particularly limited.

[0155] In one embodiment of the present invention, the electrolyte may include a lithium salt.

[0156] In another embodiment of the present invention, the electrolyte may include a lithium salt and a non-aqueous solvent.

[0157] In another embodiment of the present invention, the electrolyte may include a lithium salt, a non-aqueous solvent, and an additive.

[0158] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. For example, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably used within the range of about 0.1 M to 5.0 M, for example, about 0.1 M to 3.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0159] In one embodiment of the present invention, the lithium salt may include LiTFSI.

[0160] The above non-aqueous solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. For example, the non-aqueous solvent may be an ester solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, or ε-caprolactone; an ether solvent such as dibutyl ether or tetrahydrofuran; a ketone solvent such as cyclohexanone; an aromatic hydrocarbon solvent such as benzene or fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used.

[0161] Meanwhile, in one embodiment of the present invention, the electrolyte may include a heterocyclic compound containing an oxygen atom or a sulfur atom in terms of forming a polymer protective film capable of suppressing the formation of lithium dendrites, reducing electrolyte decomposition and side reactions on the surface of a lithium-based metal. The heterocyclic compound may be a 3 to 15-membered, for example, a 3 to 7-membered, or a 5 to 6-membered heterocyclic compound. The heterocyclic compound is a heterocyclic compound unsubstituted or substituted with at least one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, an aryl group having 6 to 10 carbon atoms, a halogen group, a nitro group (-NO2), an amine group (-NH2), and a sulfonyl group (-SO2); Or it may be a multi-cyclic compound of at least one selected from the group consisting of a cyclic alkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 10 carbon atoms and a heterocyclic compound. When the heterocyclic compound is a heterocyclic compound substituted with an alkyl group having 1 to 4 carbon atoms, the radical is stabilized, so that a side reaction between the additive and the electrolyte can be suppressed. In addition, when the heterocyclic compound is substituted with a halogen group or a nitro group, a functional protective film can be formed on the surface of the lithium-based metal. The functional protective film is a stable, compact protective film, which enables uniform deposition of the lithium-based metal and can suppress a side reaction between the polysulfide and the lithium-based metal.

[0162] The heterocyclic compounds include, for example, furan, 2-methylfuran, 3-methylfuran, 2-ethylfuran, 2-propylfuran, 2-butylfuran, 2,3-dimethylfuran, 2,4-dimethylfuran, 2,5-dimethylfuran, pyran, 2-methylpyran, 3-methylpyran, 4-methylpyran, benzofuran, 2-(2-Nitrovinyl)furan, thiophene, thiophene, It may include at least one selected from the group consisting of 2-methylthiophene, 2-ethylthiphene, 2-propylthiophene, 2-butylthiophene, 2,3-dimethylthiophene, 2,4-dimethylthiophene, and 2,5-dimethylthiophene, and for example, it may include at least one selected from the group consisting of 2-methylfuran and 2-methylthiophene.

[0163] Meanwhile, in one embodiment of the present invention, the non-aqueous solvent of the electrolyte may include an ether solvent in order to improve the charge / discharge performance of the battery. These ether solvents include cyclic ethers (e.g., 1,3-dioxolane, tetrahydrofuran, tetrohydropyran, etc.), linear ether compounds (e.g., 1,2 dimethoxyethane, etc.), low viscosity fluorinated ethers, such as (1H,1H,2'H,3H-decafluorodipropyl ether), difluoromethyl 2,2,2-trifluoroethyl ether, 1,2,2,2-tetrafluoroethyl trifluoromethyl ether, 1,1,2,3,3,3-hexafluoropropyl difluoromethyl There are ethers (1,1,2,3,3,3-Hexafluoropropyl difluoromethyl ether), 1H,1H,2'H,3H-decafluorodipropyl ether, pentafluoroethyl 2,2,2-trifluoroethyl ether, 1H,1H,2'H-perfluorodipropyl ether), and a mixture of one or more of these may be included as a non-aqueous solvent.

[0164] In one embodiment of the present invention, the non-aqueous solvent may include a mixture of 2-methyl furan and dimethoxyethane.

[0165] In one embodiment of the present invention, the non-aqueous solvent may include a mixture of 2-methyl furan and dimethoxyethane having a volume ratio of about 5:1 (v / v) to 1:5 (v / v), for example, about 1:1 (v / v) to 1:5 (v / v).

[0166] In one embodiment of the present invention, the additive may be used without particular limitation as long as it is an additive that can be used in a lithium sulfur battery for the purpose of improving the life characteristics of the battery, suppressing the decrease in battery capacity, improving the discharge capacity of the battery, etc. The additive may be included in an amount of about 0.1 wt% to 10 wt%, for example, 0.1 wt% to 5 wt%, based on the total weight of the electrolyte.

[0167] In one embodiment of the present invention, the additive may include, for example, a nitrogen compound, and may include, for example, LiNO3.

[0168] Meanwhile, in one embodiment of the present invention, the lithium-sulfur battery of the present invention may have a ratio (El / S) of the total weight of the electrolyte to the total weight of the sulfur element (S) in the positive electrode of, for example, 3.5 g / g or less, for example, 3.3 g / g or less, or 3.2 g / g or less. In addition, the lithium-sulfur battery may have a ratio (El / S) of the total weight of the electrolyte to the total weight of the sulfur element (S) in the positive electrode of about 2.0 g / g to 3.5 g / g, for example, 2.0 g / g to 3.0 g / g, or 2.5 g / g to 3.0 g / g. When the sulfur-carbon composite according to the present invention is used, a lithium-sulfur battery having an El / S ratio within the above-described range can be realized, and thus, an effect of improving energy density can be exhibited. However, a lithium-sulfur battery using the sulfur-carbon composite having an El / S ratio higher than the above-described range can also be realized, and the present invention is not limited thereto.

[0169] In one embodiment of the present invention, the El / S ratio can be calculated by measuring the weight of sulfur from a sulfur-based material introduced into the positive electrode and measuring the weight of the electrolyte introduced in the manufacturing step of a lithium sulfur battery.

[0170] In one embodiment of the present invention, the El / S ratio may be measured by measuring the weight of sulfur in the positive electrode according to the method for measuring the sulfur loading amount in the positive electrode based on the manufactured and finished lithium sulfur battery, disassembling the battery at a state of charge, for example, SOC (State of Charge) 100%, extracting the electrolyte from the positive electrode, negative electrode, separator, and case, measuring the weight of all remaining components, and then using the value obtained by subtracting the weight of the remaining components after extraction from the weight of the finished lithium sulfur battery as the weight of the electrolyte.

[0171] In one embodiment of the present invention, the lithium sulfur battery may be a battery having a high energy density, for example, a battery having an energy density of 350 Wh / kg or more.

[0172] For example, the energy density of the lithium sulfur battery may be, but is not limited to, about 350 Wh / kg to 450 Wh / kg.

[0173] In one embodiment of the present invention, the energy density of the lithium sulfur battery can be calculated according to the following equation by measuring the discharge capacity by discharging to 1.8 V at a rate of 0.5 C in CC (Constant Current) mode at 25°C and charging to 2.5 V at a constant current of 0.2 C.

[0174] Energy density = [(discharge capacity X driving voltage)] / (cell weight)

[0175]

[0176] In addition, according to another aspect of the present invention, a battery module including the lithium-sulfur battery as a unit cell is provided.

[0177] The above battery module can be used as a power source for medium and large-sized devices that require high-temperature stability, long cycle characteristics, and high capacity characteristics.

[0178] Examples of the above medium- to large-sized devices include, but are not limited to, power tools powered by an electric motor; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (Escooters); electric golf carts; and power storage systems.

[0179]

[0180] Hereinafter, the present invention will be described in detail with reference to examples, drawings, etc.

[0181] [Manufacturing of lithium sulfur batteries]

[0182] Manufacturing of anodes

[0183] An aluminum foil was prepared as a current collector, and an electrode slurry prepared by mixing 96 wt% of a sulfur-carbon composite (S8:CNT = 75:25) and 4 wt% of polyacrylic acid (PAA, poly(acrylic acid)) was applied to one surface of the prepared current collector, and then dried to prepare a positive electrode.

[0184] Tables 1 and 2 below list the thickness of the current collector used in the manufacture of the electrode, the loading amount of sulfur (S8) in the electrode, and the values ​​according to Equation 1 below.

[0185] [Formula 1]

[0186]

[0187] In the above equation 1,

[0188] The unit of weight of the electrode and the weight of the current collector is grams (g).

[0189] The loading amount of the electrode is the loading amount of sulfur in the electrode, and the unit is mAh / cm 2 am.

[0190]

[0191] Manufacturing of lithium sulfur batteries

[0192] The electrode manufactured above was used as an anode, and lithium metal having a thickness of 60 μm was prepared as an anode.

[0193] An electrode assembly was prepared by positioning the positive and negative electrodes so that they face each other and interposing a 12 ㎛ thick polyethylene separator (Celgard, PE12) between them.

[0194] The prepared electrode assembly was stored in a pouch-type case, and an electrolyte solution containing 0.75 M lithium salt (LiTFSI) and 3 wt% lithium nitrate (LiNO3) dissolved in an organic solvent mixed with 2-methyl furan (2-MeF) and dimethoxyethane (DME) in a volume ratio of 3:7 was injected so that the El / S ratio became 2.5 g / g, thereby manufacturing a lithium sulfur battery.

[0195] Table 1, Table 2 and Figure 1 below show the weight ratio of the positive electrode current collector (Al foil) in the manufactured pouch-type battery.

[0196]

[0197] [Performance Evaluation of Lithium Sulfur Battery]

[0198] energy density

[0199] Each of the lithium sulfur batteries manufactured above was discharged at a constant current (CC) mode at room temperature (25°C) at a 0.5 C rate until 1.8 V, and then charged at a constant current (CC) mode at a 0.3 C rate until 2.5 V, and the discharge capacity per weight of sulfur (mAh / g (weight of sulfur)) was measured.

[0200] Meanwhile, the energy density was measured from the measured discharge capacity according to Equation 2 below, and the relative values ​​of the energy density when each of Comparative Example 1 (Table 1) and Comparative Example 4 (Table 2) using a current collector with a thickness of 20 ㎛ for each loading amount was used as a reference were shown in Table 1, Table 2, and Fig. 2.

[0201] [Formula 2]

[0202] Energy density (Wh / kg) = {[(discharge capacity (mAh / g) X operating voltage (V)) / 1000] / (cell weight (kg))}

[0203]

[0204] Sulfur (S8) content (%) in sulfur-carbon composite, current collector thickness (㎛), loading (mAh / cm 2 )Equation 1 Weight ratio of Al foil in the battery (%) Energy density (relative value, %) Comparative example 175 205.04 2.20 11.38 100.0 Comparative example 275 125.07 0.34 7.18 104.8 Comparative example 375 105.08 4.40 6.05 106.5 Example 175 8 5.01 05.5 4.90 107.8 Example 275 6 5.01 40.73.72 109.1

[0205] Sulfur (S8) content (%) in sulfur-carbon composite, current collector thickness (㎛), loading (mAh / cm 2 )Equation 1 Weight ratio of Al foil in the battery (%) Energy density (relative value, %) Comparative example 475 20 2.34 2.75 20.86 100.0 Comparative example 575 122.37 1.25 13.70 109.5 Comparative example 675 102.38 5.5 111.69 112.1 Example 375 8 2.31 06.9 9.59 115.0 Example 475 6 2.31 42.5 7.37 117.8

[0206] In Table 1, the loading amount of the electrode in Comparative Examples 1, 2, 3 and Examples 1 and 2 was 5.0 mAh / cm 2 In the case of a relatively high-loading electrode, the loading amount of the electrode in Comparative Examples 4, 5, 6 and Examples 3 and 4 in Table 2 is 2.3 mAh / cm 2This is the case of a relatively low loading electrode. Referring to Fig. 1, in the case of a high loading electrode (loading amount 5.0 mAh / cm 2 )(Comparative Examples 1, 2, 3 and Examples 1, 2) Low loading electrode (loading amount 2.3 mAh / cm 2 )(Comparative Examples 4, 5, 6 and Examples 3, 4) it can be confirmed that the mass ratio of the aluminum thin film is relatively high. This indicates that the smaller the loading amount, the greater the change in the weight ratio of the current collector. In addition, it can be confirmed that the mass ratio of the aluminum thin film naturally decreases as the thickness of the aluminum thin film decreases.

[0207] Referring to Figure 2, when the loading amount is small (loading amount 2.3 mAh / cm 2 )(Comparative Examples 4, 5, 6 and Examples 3, 4), since the specific gravity of aluminum in the electrode is relatively large. Compared to the high-loading electrode (loading amount 5.0 mAh / cm 2 )(Comparative Examples 1, 2, 3 and Examples 1, 2) It can be confirmed that the slope of increase in energy density becomes steeper as the thickness of the aluminum thin film decreases.

[0208]

[0209] [Evaluation Results]

[0210] From the results in Tables 1 and 2 above, it was confirmed that by using an electrode using an aluminum thin film current collector with a thickness of 9 ㎛ or less, the energy density of a lithium sulfur battery can be greatly improved compared to when the thickness is greater than 9 ㎛. For example, in the case of a high-loading electrode (loading amount 5.0 mAh / cm) as shown in Table 1, 2 ) When comparing Comparative Example 1, in which the thickness of the aluminum thin film collector was 20 ㎛, with Example 2, in which the thickness of the aluminum thin film collector was 8 ㎛, it was confirmed that the energy density increased by about 10% (about 9.1% to be exact). Meanwhile, the values ​​of Equation 1 in Examples 1 and 2 were 105.5 cm , respectively. 2 / mAh and 140.7 cm2 / mAh as 90 cm 2 / You can see that it is more than mAh.

[0211] Meanwhile, for electrodes with low loading as shown in Table 2 (loading amount 2.3 mAh / cm 2 ), when comparing Comparative Example 4, where the thickness of the aluminum thin film collector was 20 ㎛, with Example 4, where the thickness of the aluminum thin film collector was 6 ㎛, the relative value of the energy density increased by about 17.8%, which was confirmed to be almost twice as much as the increase in energy density compared to the electrode with a relatively high loading amount. Meanwhile, the values ​​of Equation 1 in Examples 3 and 4 were 106.9 cm 2 / mAh and 142.5 cm 2 90 cm as / mAh 2 / You can see that it is more than mAh.

[0212] Meanwhile, in the comparative examples and examples above, when an aluminum thin film was used as a current collector, a parameter of about 9 ㎛ or less was calculated based on the thickness thereof, but it is not limited thereto, and the present invention may calculate parameters based on, for example, the type of current collector metal used, and the weight and density of these metals. For example, when Al, Ni, Cu, or Sus is used as a current collector, the density (d) (g / cm) of these metals 3 ) and the weight per unit area of ​​the metal (mg / cm) based on the weight value 2 ) can also be selected as a condition for the value to be less than a specific value. For example, according to one embodiment, the weight per unit area of ​​the entire collector (mg / cm 2 ) value is less than or equal to "0.9xd", the energy density of the sulfur battery can be improved, as in the case where the thickness of the aluminum thin film collector is less than 9 ㎛. In this case, the densities of Al, Ni, Cu, and Sus are each 2.7 g / cm 3 , 8.91 g / cm 3 , 8.96 g / cm 3 and 7.93 g / cm 3When the relationship of "0.9xd" is applied, the weight per unit area of ​​the collector is 2.43 mg / cm for the Al collector. 2 In the case of the Ni collector, the weight per unit area of ​​the collector is 8.019 mg / cm 2 In the case of Cu collector, the weight per unit area of ​​the collector is 8.064 mg / cm 2 In the case of the Sus collector, the weight per unit area of ​​the collector is 7.137 mg / cm 2 In the case below, the condition corresponding to the condition that the aluminum thin film current collector described above is 9 ㎛ or less is met.

[0213] Although the present disclosure has been described above with reference to embodiments thereof, it will be understood by those skilled in the art or those with ordinary knowledge in the art that various modifications and changes to the present invention may be made without departing from the spirit and technical scope of the present invention as set forth in the claims below. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

Claims

1. The entire house and An electrode comprising an electrode active material layer positioned on at least one side of the above-mentioned collector, The above electrode active material layer comprises a sulfur-carbon complex and a binder, The above sulfur-carbon composite comprises a porous carbon material and a sulfur-based material, The above electrode comprises aluminum (Al) and has a thickness of about 9 ㎛ or less.

2. In claim 1, The above electrode has a value of about 90 cm according to the following equation 1. 2 Electrode satisfying / mAh or more: [Formula 1] In the above equation 1, The unit of weight of the electrode and the weight of the current collector is gram (g). The electrode loading amount is the sulfur loading amount in the electrode, and the unit is mAh / cm. 2 am.

3. In claim 2, The value according to the above formula 1 is approximately 100 cm 2 / mAh to 150 cm 2 / Electrode satisfying mAh.

4. In claim 1, An electrode having a thickness of the entire body of the electrode of about 5 ㎛ to 9 ㎛.

5. In claim 1, An electrode, wherein the content of sulfur-based material in the electrode active material layer is about 65 wt% or more.

6. In claim 1, The sulfur loading is about 5 mAh / cm 2 Below, electrode.

7. In claim 1, The sulfur loading is about 3.5 mAh / cm 2 Below, electrode.

8. In claim 1, The above electrode is made only of aluminum (Al).

9. In claim 1, The above-mentioned electrode comprises aluminum, stainless steel, nickel, titanium, calcined carbon, silver or two or more of these components.

10. In claim 1, The above electrode is in the form of a film, a sheet, a foil, a net, a porous body, a foam, or a non-woven fabric.

11. The entire house and An electrode comprising an electrode active material layer positioned on at least one side of the above-mentioned collector, The above electrode active material layer comprises a sulfur-carbon complex and a binder, The above sulfur-carbon composite comprises a porous carbon material and a sulfur-based material, The above-mentioned collector comprises a specific metal, and the weight per unit area of ​​the specific metal (mg / cm) 2 ) Electrode whose value satisfies the value of “0.9xdensity(d)” or less.

12. In claim 11, The above specific metal is an electrode made of any one of aluminum (Al), nickel (Ni), copper (Cu) or stainless steel (Sus).

13. In claim 11, The above electrode is in the form of a film, a sheet, a foil, a net, a porous body, a foam, or a non-woven fabric.

14. Including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte; At least one of the positive and negative electrodes comprises a current collector and an electrode active material layer positioned on at least one side of the current collector, The above electrode active material layer comprises a sulfur-carbon complex and a binder, The above sulfur-carbon composite comprises a porous carbon material and a sulfur-based material, A lithium sulfur battery, wherein the entire body contains aluminum (Al) and has a thickness of about 9 ㎛ or less.

15. In claim 14, A lithium sulfur battery, wherein the weight ratio of the electrolyte and sulfur (El / S) is about 3.5 g / g or less.

16. In claim 14, A lithium sulfur battery having an energy density of about 350 Wh / kg or more.

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