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KR-20260065577-A - A current collector for an electrode and a cathode for lithium-sulfur battery comprising the same

KR20260065577AKR 20260065577 AKR20260065577 AKR 20260065577AKR-20260065577-A

Abstract

In this invention, a primer layer is formed between the positive current collector and the positive active material layer, ensuring that the two layers remain in close contact even after repeated charging and discharging. Furthermore, the primer layer contains lithium-substituted carboxymethylcellulose (Li-CMC), which provides a thickening effect. Additionally, by controlling the Na + ion content in the primer layer to produce a binder with a low Na + ion content, electrochemical performance degradation is prevented. Moreover, since an aqueous solvent is used during the primer layer coating process, this invention poses a low risk to the human body and the environment.

Inventors

  • 이미진
  • 김봉수
  • 한동협

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260508
Application Date
20251031
Priority Date
20241031

Claims (18)

  1. The whole house and It includes an anode portion disposed on at least one side surface of the above-mentioned current collector, The above anode comprises an anode active material layer and a primer layer, and The above anode comprises a polymer resin for binder. The polymer resin for the binder above includes a cellulose-based polymer resin and a dot-type polymer resin, and A cathode for a lithium-sulfur battery, wherein the above-mentioned cathode has a sodium ion (Na + ) content of 500 ppm or less relative to the weight of the cathode.
  2. In paragraph 1, The above primer layer comprises a polymer resin for conductive material and binder, and The polymer resin for the binder above includes a cellulose-based polymer resin and a dot-type polymer resin, and A cathode for a lithium-sulfur battery having a sodium ion (Na + ) content of 150 ppm or less relative to the weight of the primer layer.
  3. In paragraph 1, The above positive active material layer comprises a positive active material and a polymer resin for a binder, and The polymer resin for the binder above includes a cellulose-based polymer resin and a dot-type polymer resin, and A cathode for a lithium-sulfur battery having a sodium ion (Na + ) content of 150 ppm or less relative to the weight of the cathode active material layer.
  4. In paragraph 1, A cathode for a lithium-sulfur battery, wherein the above-mentioned cellulose-based polymer resin comprises carboxymethylcellulose (CMC), and the CMC comprises sodium ion-substituted CMC, lithium ion-substituted CMC, or both, which are forms of carboxymethylcellulose substituted with metal ions.
  5. In paragraph 1, A cathode for a lithium-sulfur battery, wherein the polymer resin for the binder comprises 10% to 50% by weight of Li-CMC relative to 100% by weight of the total polymer resin.
  6. In paragraph 1, A positive electrode for a lithium-sulfur battery, wherein the above current collector is a conductive substrate comprising a conductive metal, and the conductive substrate is a polymer-metal composite film comprising a metal thin film or a polymer thin film having a conductive metal formed into a thin plate shape and a conductive metal layer disposed on at least one surface of the polymer thin film.
  7. In paragraph 1, The above current collector is a positive electrode for a lithium-sulfur battery having a thickness of 3㎛ to 12㎛.
  8. In paragraph 1, The above point-shaped polymer resins are styrene butadiene rubber (SBR), butadiene rubber (BR), nitrile butadiene rubber (NBR), styrene butadiene styrene block polymer (SBS), styrene ethylene butadiene block polymer (SEB), styrene-(styrene butadiene)-styrene block polymer, natural rubber (NR), isoprene rubber (IR), ethylene-propylene-diene terpolymer (EPDM), poly(ethylene-co-propylene-co-5-methylene-2-norbornene) polytetrafluoroethylene (PTFE), polyvinylidene fluoride, polyvinyl chloride, polyvinylidene fluoride-co-hexafluoropropylene, and polyvinylidene Polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polyethylhexyl acrylate, polybutylacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, polyethylene, polypropylene, ethylene vinyl acetate copolymer (polyethylene-co-vinyl acetate), polyethylene oxide, polypropylene oxide, polyacrylic acid, polyarylate, cyanoethylpullulan, cyanoethylpolyvinylalcohol, or may comprise two or more of these. Specifically, the binder may be styrene butadiene rubber (SBR), nitrile A positive electrode for a lithium-sulfur battery comprising butadiene rubber (NBR), polymethylmethacrylate, polyethylhexyl acrylate, polybutyl acrylate, or two or more selected from these.
  9. In paragraph 1, The weight per area of the above primer layer is 0.03 mg/ cm² to A positive electrode for a lithium-sulfur battery having a content of 0.5 mg/cm² or less .
  10. In paragraph 1, A positive electrode for a lithium-sulfur battery having a weight per unit area of the positive electrode active material layer of 0.30 mAh/ cm² to 3.5 mAh/ cm² or less.
  11. In paragraph 2, The above conductive material is a positive electrode for a lithium-sulfur battery comprising 20 to 40 weight percent of 100 weight percent of a primer layer.
  12. In paragraph 1, A positive electrode for a lithium-sulfur battery, wherein the polymer resin for the binder is included in an amount of 60% to 80% by weight of the primer layer in 100% by weight of the above-mentioned primer layer.
  13. In paragraph 2, The above conductive material comprises at least one of a conductive metal and a carbon material such as graphene, CNT, carbon black, or carbon fiber. A cathode for a lithium-sulfur battery.
  14. A positive electrode for a lithium-sulfur secondary battery according to claim 1, wherein a positive electrode active material layer is formed on top of the primer layer, and the positive electrode active material layer comprises sulfur ( S8 ) or a sulfur-based compound as the positive electrode active material.
  15. In Paragraph 14, A cathode for a lithium-sulfur secondary battery, wherein the sulfur (S 8 ) and/or sulfur-based compound is included in the cathode active material in the form of a sulfur-carbon composite combined with a porous carbon material.
  16. A lithium-sulfur secondary battery comprising a negative electrode and a positive electrode, wherein the negative electrode comprises lithium metal, an alloy of lithium and a heterogeneous metal, or one or more of these as a negative electrode active material, and the positive electrode conforms to any one of claims 1 to 15.
  17. In Paragraph 16, A lithium-sulfur secondary battery in which the anode and cathode are insulated by a separator or a solid electrolyte membrane.
  18. A current collector for an electrochemical device comprising a primer layer, wherein the primer layer comprises a conductive material and a polymer resin for a binder, wherein the polymer resin for the binder comprises a cellulose-based polymer resin and a dot-shaped polymer resin, and wherein the sodium ion (Na+) content relative to the weight of the primer layer is 150 ppm or less.

Description

A current collector for an electrode and a cathode for a lithium-sulfur battery comprising the same, comprising a primer layer. The present invention relates to an electrode current collector comprising a primer layer and an electrode comprising the same. Furthermore, the present invention relates to a lithium-sulfur secondary battery comprising the electrode. The application range of lithium-ion batteries extends not only to portable electronic devices but also to electric vehicles As applications expand to EVs and energy storage systems (ESS), the demand for high-capacity, high-energy-density, and long-life lithium-ion batteries is increasing. Among various lithium secondary batteries, the lithium-sulfur battery is a battery system that uses a sulfur compound containing a sulfur-sulfur (S-S) bond 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. 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. In addition, the lithium-sulfur battery has a theoretical capacity of 1,675 mAh/g derived from the conversion reaction between lithium ions and sulfur (S8 + 16Li+ + 16e- → 8Li2S) at the cathode, and when lithium metal is used as the anode, the theoretical energy density is 2,600 Wh/kg. Since the theoretical energy density of the lithium-sulfur battery 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), the lithium-sulfur battery is attracting attention among the secondary batteries developed so far as it is a high-capacity, eco-friendly, and low-cost lithium secondary battery. 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. This enables the realization of high-capacity, high-energy-density batteries, and thus, various studies are being conducted on them as next-generation battery systems. However, there is a problem where the electrode active material layer peels off from the current collector due to the volume change of sulfur during charging and discharging, so improvement is required. 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. Figure 1 is a graph comparing the adhesion strength of the anodes prepared in Example 1 and Comparative Example 1, respectively. Figure 2 shows a cross-section of the anode of Example 1, and Figure 3 shows a cross-section of the anode of Comparative Example 1. Figures 4 and 5 are graphs comparing the power density measured for the batteries of Example 1 and Comparative Example 1. Figure 6 shows the discharge capacity per cycle for the batteries of Example 1 and Comparative Example 1. Figure 7 is a graph showing the Coulomb efficiency confirmed for the batteries of Example 1 and Comparative Example 1. Hereinafter, the present invention will be described in more detail to aid in understanding the invention. 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. 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. 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. Throughout this specification, the description of 'A and/or B' means 'A or B or both'. 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 cent