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KR-102963261-B1 - All Solid secondary battery, and Method for preparing the same

KR102963261B1KR 102963261 B1KR102963261 B1KR 102963261B1KR-102963261-B1

Abstract

A solid-state secondary battery and a method for manufacturing the same are disclosed, comprising a solid electrolyte layer disposed between a negative electrode layer and a positive electrode layer, wherein the solid electrolyte layer is disposed adjacent to the negative electrode and contains a first solid electrolyte layer containing a first solid electrolyte, and a second solid electrolyte layer disposed adjacent to the positive electrode and contains a second solid electrolyte, wherein the first solid electrolyte has a higher lithium ion conductivity than the second solid electrolyte and the difference in lithium ion conductivity is 2 mS/cm or more.

Inventors

  • 구준환
  • 스기모토 토시노리

Assignees

  • 삼성에스디아이 주식회사

Dates

Publication Date
20260508
Application Date
20200131

Claims (20)

  1. It includes a solid electrolyte layer disposed between the cathode layer and the anode layer, and The above solid electrolyte layer is disposed adjacent to the cathode layer and comprises a first solid electrolyte layer containing a first solid electrolyte, and It comprises a second solid electrolyte layer disposed adjacent to the above-mentioned anode layer and containing a second solid electrolyte, and The first solid electrolyte has a higher lithium ion conductivity compared to the second solid electrolyte, and the difference in lithium ion conductivity is 2 mS/cm or more, and The above first solid electrolyte layer is directly disposed on the cathode layer and The above second solid electrolyte layer is directly disposed on the anode layer, and The above first solid electrolyte is represented by the following chemical formula 1 and comprises a compound having an argyrodite crystal structure, and The above-mentioned second solid electrolyte is represented by the following chemical formula 2 and comprises a compound having an azirodite crystal structure, forming an all-solid-state secondary battery: <Chemical Formula 1> Li a M x PS b (X)c(Cl) d In Chemical Formula 1, M is Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof, and X is Br, I, or a combination thereof, and 0≤x≤0.07, a is a number from 5 to 6 and b is a number from 4 to 6, c>0, d>0, 0<c+d≤2, 5≤a+x≤6, and <Chemical Formula 2> Li a M x PS b (Cl) d In chemical formula 2, M is Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof, and 0≤x≤0.07, a is a number from 5 to 6 and b is a number from 4 to 6, 0<d≤2, 5≤a+x≤6.
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  7. An all-solid-state secondary battery according to claim 1, wherein the difference in ionic conductivity between the first solid electrolyte and the second solid electrolyte is 2 mS/cm to 20 mS/cm.
  8. In paragraph 1, The ratio of packing density to true density of the first solid electrolyte layer and the second solid electrolyte layer is 60% or more, and The ratio of packing density to true density of the first solid electrolyte layer is smaller than the ratio of packing density to true density of the second solid electrolyte layer. All-solid-state secondary battery in which the difference in the ratio of packing density to true density between the first solid electrolyte layer and the second solid electrolyte layer is 2 to 5%.
  9. A solid-state secondary battery according to claim 1, wherein the thickness ratio of the first solid electrolyte layer to the second solid electrolyte layer is 1:1 to 1:10.
  10. A solid-state secondary battery according to claim 1, wherein the thickness of the second solid electrolyte layer is greater than the thickness of the first solid electrolyte, the thickness of the first solid electrolyte layer is 1 to 35 μm, and the thickness of the second solid electrolyte layer is 10 to 60 μm.
  11. The all-solid-state secondary battery according to claim 1, wherein the total thickness of the solid electrolyte layer is 11 to 200 μm.
  12. In claim 1, the compound represented by Chemical Formula 1 is a solid-state secondary battery in which the compound represented by Chemical Formula 3 below. <Chemical Formula 3> Li a M x PS b (Br)c(Cl) d In chemical formula 3, M is Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof, and X is Br, I, or a combination thereof, and 0≤x≤0.07, a is a number from 5 to 6 and b is a number from 4 to 6, c>0, d>0, 0<c+d≤2, 5≤a+x≤6.
  13. In claim 12, an all-solid-state secondary battery in which 0≤x≤0.05 in the above chemical formula 3.
  14. A solid-state secondary battery according to claim 1, wherein the compound represented by Chemical Formula 1 is a compound represented by the following Chemical Formula 4: <Chemical Formula 4> (Li 1-x1 M x1 ) 7-y PS 6-y (Br 1-x2 (Cl) x2 ) y In the four chemical formulas, M is Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof, and 0≤x1<1, 0<x2<1, 0≤y≤2.
  15. In claim 1, the compound represented by the above chemical formula 1 is Li 5.5 PS 4.5 Cl 0.75 Br 0.75 , Li 5.5 PS 4.5 Cl 0.25 Br 1.25 , Li 5.5 PS 4.5 Cl 1.25 Br 0.25 , Li 5.5 PS 4.5 Cl 0.1 Br 1.4 , Li 5.45 Na 0.05 PS 4.5 Cl 0.25 Br 1.25 , Li 5.5 PS 4.5 Cl 0.25 Br 1.25 , Li 5.45 Na 0.05 PS 4.5 Cl 0.1 Br 1.4 , Li 5.45 Na 0.05 PS 4.5 Cl 0.1 Br 1.4 , Li 5 Na 0.05 PS 4 Cl 0.01 Br 1.99 , Li 5.74 PS 4.74 Cl 0.01 Br 1.25 , Li 5 PS 4 Cl 0.01 Br 1.99 , Li 5.45 K 0.05 PS 4.5 Cl 0.25 Br 1.25 , Li 5.45 K 0.05 PS 4.5 Cl 0.1 All-solid-state secondary battery comprising Br 1.4 , Li 5.45 , K 0.05, PS 4.5, Cl 0.1 , Br 1.4 , Li 5 , K 0.05 , PS 4, Cl 0.01 , Br 1.99 , or a combination thereof.
  16. In claim 1, the compound represented by the above chemical formula 1 comprises Li 5.75 PS 4.75 Cl 1.25, Li 5.75 PS 4.5 Cl 1.5, Li 5.5 PS 4.5 Cl 1.5 , Li 5.45 Na 0.05 PS 4.5 Cl 1.5 , Li 5.45 K 0.05 PS 4.5 Cl 1.5 , Li 5.74 PS 4.74 Cl 1.26 , Li 5 Na 0.05 PS 4 Cl 2 , Li 5 K 0.05 PS 4 Cl 2 , Li 5.8 PS 4.8 Cl 1.2 , Li 5.7 Na 0.05 PS 4.75 Cl 1.25 , Li 5.7 Cu 0.05 PS 4.75 Cl 1.25 , and Li 5.65 Cu 0.1 All-solid-state secondary battery of PS 4.75 Cl 1.25 , or a combination thereof.
  17. In claim 1, the first solid electrolyte and the second solid electrolyte are both all-solid-state secondary batteries having an ionic conductivity of 1 mS/cm or more at 25°C.
  18. An all-solid-state secondary battery according to claim 1, wherein the ionic conductivity of the first solid electrolyte at 25°C is 3 to 7 mS/cm, the ionic conductivity at 45°C is 10 to 15 mS/cm, and the ionic conductivity at 60°C is 16 to 20 mS/cm.
  19. An all-solid-state secondary battery according to claim 1, wherein the ionic conductivity of the second solid electrolyte at 25°C is 1 to 5 mS/cm, the ionic conductivity at 45°C is 3 to 8 mS/cm, and the ionic conductivity at 60°C is 5 to 12 mS/cm.
  20. The all-solid-state secondary battery according to claim 1, wherein the first solid electrolyte layer and the second solid electrolyte layer contain one or more binders selected from styrene-butadiene-styrene copolymer, acrylic resin, styrene-butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene, vinylidene fluoride/hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

Description

All Solid secondary battery and method for preparing the same This relates to an all-solid-state secondary battery and a method for manufacturing the same. Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life. Currently commercially available lithium-ion batteries use electrolytes containing flammable organic solvents, so there is a possibility of overheating and fire in the event of a short circuit. In response to this, all-solid-state batteries using a solid electrolyte instead of an electrolyte are being proposed. By not using flammable organic solvents, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes. Sulfide-based solid electrolytes with excellent ionic conductivity are used as the solid electrolyte for all-solid-state batteries, and the batteries are manufactured by interposing them between the anode and cathode layers and applying pressure. However, these all-solid-state batteries exhibit low reversible capacity at high rates or frequent short circuits during repeated charging and discharging, requiring improvements. FIGS. 1a to 1c are graphs showing the voltage change according to the specific capacity of the all-solid-state secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 3. Figure 2 is a graph showing the change in relative capacity according to the discharge rate in the all-solid-state secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 3. Figure 3 is a graph showing the capacity retention rate of all-solid-state secondary batteries of Example 2, Example 3, Comparative Example 1, and Comparative Example 2. Figure 4 is a graph showing the voltage change according to the specific capacity of the all-solid-state secondary batteries of Example 2, Comparative Example 4, and Comparative Example 5. Figure 5 is a graph showing the change in relative capacity according to the discharge rate of the all-solid-state secondary batteries of Example 2, Comparative Example 4, and Comparative Example 5. Figure 6 is a graph showing the voltage change according to the specific capacity of the all-solid-state secondary battery of Example 3. Figure 7 is a graph showing the change in relative capacity according to the discharge rate of the all-solid-state secondary battery of Example 3. FIG. 8 is a graph showing the capacity retention rate of all-solid-state secondary batteries of Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 4, and Comparative Example 5. Figures 9, 10a to 10f show the results of scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDAX) analysis of an all-solid-state secondary battery prepared according to Example 2. FIGS. 11 to 13 are cross-sectional views of an all-solid-state secondary battery according to an exemplary embodiment. A solid-state secondary battery and a method for manufacturing the same according to one embodiment will be described in more detail. An all-solid-state secondary battery is provided, comprising a solid electrolyte layer disposed between a cathode layer and an anode layer, wherein the solid electrolyte layer comprises a first solid electrolyte layer disposed adjacent to the cathode and containing a first solid electrolyte, and a second solid electrolyte layer disposed adjacent to the anode and containing a second solid electrolyte, wherein the first solid electrolyte has a higher lithium ion conductivity than the second solid electrolyte and the difference in lithium ion conductivity is 2 mS/cm or more. The difference in ionic conductivity between the first solid electrolyte and the second solid electrolyte is 2 to 20 mS/cm, for example, 2 to 10 mS/cm. According to another embodiment, the difference in ionic conductivity between the first solid electrolyte layer containing the first solid electrolyte and the second solid electrolyte layer containing the second solid electrolyte is 2 mS/cm or more, for example, 2 to 20 mS/cm, for example, 2 to 10 mS/cm. In the manufacturing of all-solid-state secondary batteries, it is common practice to form a tight interface between the electrode layer and the solid electrolyte layer by interposing a solid electrolyte layer between the anode and cathode layers and applying pressure. However, all-solid-state secondary batteries manufactured according to this method still suffer from problems such as low reversible capacity at high rates or frequent short circuits, necessitating improvements. Accordin