Search

KR-102962370-B1 - electrochemical device

KR102962370B1KR 102962370 B1KR102962370 B1KR 102962370B1KR-102962370-B1

Abstract

The present invention relates to an electrochemical device capable of preventing the depletion of salts and additives in an electrolyte. An electrochemical device according to one embodiment of the present invention may comprise: a positive electrode; a lithium metal negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte comprising tin chloride ( SnCl2 ).

Inventors

  • 이도중
  • 김기현

Assignees

  • 주식회사 엘지에너지솔루션

Dates

Publication Date
20260507
Application Date
20220111

Claims (14)

  1. An electrochemical device comprising: a positive electrode; a lithium metal negative electrode; a separator interposed between the positive electrode and the negative electrode; and a non-aqueous electrolyte comprising tin chloride ( SnCl₂ ); The content of the tin chloride is 0.5% to 4% by weight relative to 100% by weight of the total non-aqueous electrolyte, and An electrochemical device characterized in that the above electrochemical device is a lithium-sulfur battery.
  2. delete
  3. In paragraph 1, An electrochemical device characterized by the content of the tin chloride being 1% to 2% by weight relative to 100% by weight of the total non-aqueous electrolyte.
  4. In paragraph 1, An electrochemical device characterized by including a Li-Cl and Li-Sn alloy protective layer on the surface of the above lithium metal negative electrode.
  5. In paragraph 1, The above-mentioned non-aqueous electrolyte comprises a first solvent comprising a heterocyclic compound that has or does not contain one or more double bonds and contains one or more of an oxygen atom and a sulfur atom; A second solvent comprising one or more of ether-based compounds, ester-based compounds, amide-based compounds, and carbonate-based compounds; lithium salt; and An electrochemical device characterized by further including lithium nitrate.
  6. In paragraph 5, The above-mentioned lithium salt is an electrochemical device characterized by comprising LiCl, LiBr , LiI , LiClO₄ , LiBF₄ , LiB₁₀Cl₁₀ , LiPF₆ , LiCF₃SO₃ , LiCF₃CO₂, LiC₄BO₅ , LiAsF₆ , LiSbF₆, LiAlCl₄, CH₃SO₃Li, CF₃SO₃Li, (C₂F₅SO₂)₂NLi, (SO₂F)₂NLi, (CF₃SO₂ ) ₂NLi , ( CF₃SO₂ ) ₃Cl₆ , lithium chloroborane , lithium lower aliphatic carboxylate having 4 or fewer carbon atoms, lithium 4 - phenylborate, lithium imide, or two or more of these.
  7. In paragraph 5, An electrochemical device characterized by the concentration of the lithium salt being 0.2 to 2.0 M.
  8. In paragraph 5, The electrochemical element is characterized in that the above heterocyclic compound is a heterocyclic compound of 3 to 15 members substituted or unsubstituted with one or more 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, an amine group, and a sulfonyl group, or a polycyclic compound of a heterocyclic compound and one or more of a cyclic alkyl group having 3 to 8 carbon atoms and an aryl group having 6 to 10 carbon atoms.
  9. In paragraph 5, The above heterocyclic compounds are 1,3-dioxolane, 4,5-diethyl-1,3-dioxolane, 4,5-dimethyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 4-ethyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, 4-methyl-1,3-dioxane and 2-methyl-1,3-dioxane, 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, An electrochemical device characterized by comprising 2-methylthiophene, 2-ethylthiophene, 2-propylthiophene, 2-butylthiophene, 2,3-dimethylthiophene, 2,4-dimethylthiophene, 2,5-dimethylthiophene, or two or more of these.
  10. In paragraph 5, The electrochemical element is characterized in that the ether-based compound of the second solvent comprises dimethyl ether, diethyl ether, dipropyl ether, methyl ethyl ether, methyl propyl ether, ethyl propyl ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol methyl ether, polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol methyl ether, or two or more of these.
  11. In paragraph 1, The above-mentioned non-aqueous electrolyte is an electrochemical device characterized by further including lanthanum nitrate, potassium nitrate, cesium nitrate, magnesium nitrate, barium nitrate, lithium nitrite, potassium nitrite, cesium nitrite, or two or more of these.
  12. In paragraph 1, The above-mentioned non-aqueous electrolyte is characterized by further comprising 1,3 - dioxolane as a first solvent, dimethoxyethane as a second solvent, ( CF₃SO₂ ) ₂NLi as a lithium salt, and lithium nitrate.
  13. delete
  14. delete

Description

electrochemical device The present invention relates to an electrochemical device, and more specifically, to an electrochemical device with improved lifespan characteristics by preventing the depletion of salts and additives in the electrolyte. As interest in energy storage technology continues to grow, research and development in electrochemical devices are steadily increasing as application fields expand to include mobile phones, tablets, laptops, camcorders, and even electric vehicles (EVs) and hybrid electric vehicles (HEVs). Electrochemical devices are receiving the most attention in this regard, and recently, research and development in the design of new electrodes and batteries has been leading to improvements in capacity density and specific energy for the development of these devices. Among such electrochemical devices, lithium metal secondary batteries that use lithium metal as the negative electrode, such as lithium-sulfur batteries (Li-S batteries), are attracting attention as next-generation high-capacity batteries because they use lightweight lithium metal as the negative electrode active material and have a very high theoretical capacity of 3,862 mAh/g. In lithium-sulfur batteries, the reduction reaction of sulfur and the oxidation reaction of lithium metal occur during discharge, and at this time, sulfur forms a linear structure of lithium polysulfide (LiPS) from a cyclic structure of S8 . Such lithium-sulfur batteries are characterized by exhibiting stepwise discharge voltages until the polysulfide is completely reduced to Li2S . However, in lithium metal secondary batteries such as lithium-sulfur batteries, the charge/discharge efficiency decreases during the charge/discharge process due to reasons such as side reactions of the electrolyte (deposition of by-products due to the decomposition of the electrolyte) and instability of lithium metal (short circuits caused by the growth of dendrites on the lithium metal negative electrode), and the battery life deteriorates. In particular, lithium metal, which is the negative electrode active material, easily forms large-area dendrites and reacts with salts and additives in the electrolyte to form SEI (solid electrolyte interphase), thereby continuously consuming the salts and additives in the electrolyte and consequently accelerating the degradation of the battery. Therefore, in order to use lithium metal as the anode, it is necessary to develop technology to prevent the depletion of salts and additives in the electrolyte. 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 figure showing the interfacial resistance of a lithium-lithium symmetric cell prepared in Example 2-1. Figure 2 is a figure showing the interfacial resistance of a lithium-lithium symmetric cell prepared in Example 2-2. Figure 3 is a figure showing the interfacial resistance of the lithium-lithium symmetric cell prepared in Example 2-3. Figure 4 is a figure showing the interfacial resistance of the lithium-lithium symmetric cell prepared in Example 2-4. Figure 5 is a figure showing the interfacial resistance of the lithium-lithium symmetric cell prepared in Example 2-5. Figure 6 is a figure showing the interfacial resistance of the lithium-lithium symmetric cell prepared in Example 2-6. Figure 7 is a figure showing the interfacial resistance of a lithium-lithium symmetric cell prepared in Comparative Example 2-1. Figure 8 is a figure showing the cycle life performance of the lithium-lithium symmetric cell prepared in Example 2-1. Figure 9 is a figure showing the cycle life performance of the lithium-lithium symmetric cell prepared in Example 2-1. Figure 10 is a figure showing the cycle life performance of the lithium-lithium symmetric cell prepared in Example 2-1. Figure 11 is a figure showing the cycle life performance of the lithium-lithium symmetric cell prepared in Example 2-1. Figure 12 is a figure showing the cycle life performance of the lithium-lithium symmetric cell prepared in Example 2-1. Figure 13 is a figure showing the cycle life performance of the lithium-lithium symmetric cell prepared in Example 2-1. Figure 14 is a figure showing the cycle life performance of the lithium-lithium symmetric cell prepared in Example 2-1. FIG. 15 is a figure showing the cycle life performance of lithium-sulfur batteries prepared in Examples 3-1 to 3-6 and Comparative Example 3-1. Figure 16 is a figure showing the surface of the lithium metal negative electrode after operating the lithium-sulfur battery prepared in Example 3-3 for 100 cycles. Hereinafter, preferred embodiments of the present invention will be described in detail. Prior to this, terms