Search

KR-20260064272-A - Solid electrolyte, all solid secondary battery comprising the same, and manufacturing method thereof

KR20260064272AKR 20260064272 AKR20260064272 AKR 20260064272AKR-20260064272-A

Abstract

An embodiment of the present invention provides a solid electrolyte for an all-solid-state secondary battery, comprising: a first solid electrolyte layer; and a second solid electrolyte layer disposed on the first solid electrolyte layer, wherein the second solid electrolyte layer is porous and includes pores with an average size of 1 to 3 μm.

Inventors

  • 이상민
  • 김찬명
  • 이다온
  • 고수민

Assignees

  • 포항공과대학교 산학협력단

Dates

Publication Date
20260507
Application Date
20241031

Claims (20)

  1. As a solid electrolyte for all-solid-state secondary batteries, A first solid electrolyte layer; and It includes a second solid electrolyte layer disposed on the first solid electrolyte layer, and The above second solid electrolyte layer is porous and includes pores of an average size of 1 to 3 μm, a solid electrolyte.
  2. In paragraph 1, The pore inner walls of the second solid electrolyte layer are coated with Ag, a solid electrolyte.
  3. In paragraph 2, A solid electrolyte having a thickness of 40 to 60 nm of the Ag layer formed on the inner wall of the pores by applying the above Ag.
  4. In paragraph 1, A solid electrolyte having a porosity of 7.0% to 12.8% for the second solid electrolyte layer.
  5. In paragraph 1, The first solid electrolyte layer and the second solid electrolyte layer are solid electrolytes comprising Li 6 PS 5 Cl.
  6. In paragraph 1, The first solid electrolyte layer comprises a dense solid electrolyte, a solid electrolyte.
  7. In paragraph 1, A solid electrolyte having a ratio of the thickness of the first solid electrolyte layer to the thickness of the second solid electrolyte layer of 88:12 to 92:8.
  8. In Paragraph 7, A solid electrolyte, wherein the thickness (t2) of the second solid electrolyte layer is 4 to 80 μm.
  9. In paragraph 1, The solid electrolyte included in the first solid electrolyte layer above is a solid electrolyte comprising solid electrolyte particles having a particle size of 1 to 12 μm.
  10. In paragraph 1, The solid electrolyte included in the second solid electrolyte layer above is a solid electrolyte comprising solid electrolyte particles having a particle size of 1 to 5 μm.
  11. A solid-state secondary battery comprising: an anode layer; a cathode layer; and a solid electrolyte layer disposed between the anode layer and the cathode layer, The above-mentioned solid electrolyte layer comprises a solid electrolyte according to any one of claims 1 to 8, in an all-solid-state secondary battery.
  12. In Paragraph 11, The above cathode layer includes a cathode current collector and a cathode active material layer, and The above-mentioned negative electrode active material layer is a lithium metal layer, an all-solid-state secondary battery.
  13. In Paragraph 11, The above all-solid-state secondary battery is an all-solid-state secondary battery having an operating pressure of 2 to 6 MPa.
  14. A step of preparing a mixture by mixing solid electrolyte powder and a pore-forming agent in a ratio of 2:1 to 7:1 based on mass ratio (wt%); A step of molding the above mixture by pressing; A method for manufacturing a solid electrolyte comprising the step of heat-treating the molded mixture to remove the pore-forming agent, The above solid electrolyte is porous, comprising pores formed by removing the pore-forming agent, and A method for manufacturing a solid electrolyte in which the above pores have an average size of 1 to 3 μm.
  15. In Paragraph 14, A method for manufacturing a solid electrolyte, wherein the solid electrolyte comprises Li 6 PS 5 Cl.
  16. In Paragraph 14, A method for manufacturing a solid electrolyte, wherein the above-mentioned pore-forming agent comprises polystyrene particles.
  17. In Paragraph 16, A method for manufacturing a solid electrolyte, wherein the size (D50) of the polystyrene particles is 2.5 to 3.5 μm.
  18. In Paragraph 14, A method for manufacturing a solid electrolyte in which Ag is applied to the surface of the above-mentioned pore-forming agent.
  19. In Paragraph 18, A method for manufacturing a solid electrolyte, wherein the thickness (t3) of the Ag layer formed by applying the above Ag is 40 to 60 nm.
  20. In Paragraph 14, A method for manufacturing a solid electrolyte, wherein the solid electrolyte powder comprises particles having a particle size of 1 to 5 μm.

Description

Solid electrolyte, all solid secondary battery comprising the same, and manufacturing method thereof The present invention relates to a porous solid electrolyte, an all-solid-state secondary battery comprising the same, and a method for manufacturing the same. Conventional lithium-ion batteries use liquid electrolytes, which can easily ignite when exposed to water in the air, raising safety concerns. This safety issue is becoming an even greater concern as electric vehicles become more widespread. Consequently, research on all-solid-state secondary batteries utilizing solid electrolytes made of inorganic materials has recently been actively conducted to improve safety. All-solid-state secondary batteries are attracting attention as next-generation secondary batteries in terms of high energy density, high power output, and long lifespan, while solving safety issues caused by leakage or overheating. All-solid-state secondary batteries consist of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, among which the solid electrolyte layer requires high ionic conductivity and low electron conductivity. Meanwhile, lithium metal is considered a promising anode for next-generation batteries due to its high theoretical capacity and low standard reduction potential. However, due to its high reactivity, lithium metal induces the continuous formation and decomposition of the solid electrolyte interphase (SEI) during repeated charge-discharge cycles, leading to electrolyte depletion and causing lithium dendrite formation and severe volume changes. This degrades Coulomb efficiency and lifespan characteristics, and leads to internal short circuits and safety issues in the battery. Short circuit problems caused by metal cathodes occur in all-solid-state batteries just as severely as, or even more severe than, those in lithium-ion batteries using liquid electrolytes. To address this issue, short-circuit prevention technologies utilizing uniform lithium electrodeposition and deposition are being developed. However, short circuits still occur depending on the operating conditions of all-solid-state batteries. FIG. 1 is a cross-sectional view showing the structure of an all-solid-state secondary battery according to an embodiment of the present invention. Figure 2 is an SEM image showing a pore-forming agent according to one embodiment of the present invention. Figure 3 is an SEM image showing a pore-forming agent according to another embodiment of the present invention. Figure 4 is a step-by-step SEM image of the pore-forming agent of Figure 3. Figure 5 is a diagram showing a cross-sectional view of the pores of a solid electrolyte prepared using the pore-forming agent of Figure 3. Figure 6 is a diagram showing the XRD analysis results for the pore-forming agent. Figure 7 is a diagram comparing the XRD analysis results of a solid electrolyte according to an embodiment of the present invention and a solid electrolyte of a comparative example. FIG. 8 is a diagram comparing the EIS and CA analysis results for a solid electrolyte according to an embodiment of the present invention and a solid electrolyte of a comparative example. FIG. 9 is a diagram comparing the change in internal cell pressure of an all-solid-state secondary battery using a solid electrolyte according to an embodiment of the present invention and a solid electrolyte of a comparative example. FIG. 10 is a diagram comparing the Coulomb efficiency of an all-solid-state secondary battery using a solid electrolyte according to an embodiment of the present invention and a solid electrolyte of a comparative example. FIG. 11 is a flowchart showing a method for manufacturing a solid electrolyte according to an embodiment of the present invention. Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components regardless of drawing symbols are assigned the same reference number, and redundant descriptions thereof will be omitted. In the following description of embodiments according to the present invention, where each layer (film), region, pattern, or structure is described as being formed "on" or "under" of a substrate, each layer (film), region, pad, or pattern, "on" and "under" include both being formed "directly" and "indirectly" through another layer. Furthermore, the reference for the "on" or "under" of each layer is described based on the drawings. In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically depicted for convenience and clarity of explanation. Also, the size of each component does not entirely reflect its actual size. In this description, expressions such as “include,” “equip,” or “compose” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more