표제지
목차
Abstract (Korean) 7
Abstract 10
Chapter 1. Introduction 16
Chapter 2. Theoretical Background 20
2.1. Garnet-like solid electrolyte 20
2.1.1. Characterization of garnet-like structure 20
2.1.2. Type of metal doped Li₇La₃Zr₂O₁₂ synthesis 23
2.2. Mechanism of Ion conduction for Solid electrolyte 26
Chapter 3. Experimental Method 30
3.1. Solid electrolyte for all solid-state Li-ion battery 30
3.1.1. Synthesis of cubic phase Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ powder through high frequency focused homogeneous 30
3.1.2. Fabrication of solid electrolyte pellet 31
3.1.3. Fabrication of composite solid electrolyte sheet 32
3.2. Characterization of powder, pellet and sheet 36
Chapter 4. Result and Discussion 47
4.1. Characterization of powder 47
4.2. Characterization of pellet 57
4.3. Characterization of sheet 64
Chapter 5. Conclusion 73
Reference 76
Figure 1. Ionic conductivity of various solid electrolytes 22
Figure 2. Schematic diagram of the crystal structure and lithium arrangement of tetragonal and cubic LLZO, Crystal structure of (a)... 24
Figure 3. Schematic diagram of the crystal structure of Ga doped LLZO and Li pathway (a) Garnet structure of GaxLi₇-₃xLa₃Zr₂O₁₂...[이미지참조] 25
Figure 4. Diagram of Ionic point defect types 29
Figure 5. Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ synthesis process 34
Figure 6. Press routine of fabrication pellet 35
Figure 7. X-ray Diffraction (SmartLab, Rigaku) 40
Figure 8. Particle size analyzer (Zetasizer Nano ZS, Malvern) 41
Figure 9. FE-SEM (Sirion TM, XFLASH 6160) and TEM (TF30ST, FEI) 42
Figure 10. Thinky mixer (ARE-310) 43
Figure 11. EIS equipment for sheet 44
Figure 12. EIS equipment for pellet 45
Figure 13. Electrochemical Impedance Spectroscopy (SP-240) 46
Figure 14. TGA/DSC analysis of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ 52
Figure 15. XRD of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ powders by calcination temperature (a) 700℃, (b) 750℃, (c) 800℃, (d) 850℃, and (e) 900℃ 53
Figure 16. XRD of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ powders by calcination time of (a) 5 min, (b) 30 min, (c) 60 min, (d) 120 min, (e) 180 min,... 54
Figure 17. (a) SEM and (b) TEM images of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ powder. 55
Figure 18. Particle size of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ powders by high frequency focused homogenization time 56
Figure 19. XRD of 6,000 kg pressed Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ pellets by heat treatment temperature, (a) 800℃, (b) 900℃, (c) 1,000℃, (d) 1,150℃ 60
Figure 20. XRD of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ pellets by pressure of (a) 1,150℃ heat treatment powder, (b) 100 kg, (c) 300 kg, (d) 500 kg,... 61
Figure 21. SEM images of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ pellets cross-sec-tion by press of (a) 900 kg, (b) 2,500 kg, (c) 5,000 kg, and (d) 6,000 kg 62
Figure 22. (a) Impedance and (b) Ion conductivity of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ pellets by pressure changes 63
Figure 23. (a) SEM images of sheet and EDS elements mapping of (b) La, (c) Zr, and (d) O 67
Figure 24. Impedance of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ sheet by heat temperature changes (a) Impedance plot, (b) Ion conductivity plot 68
Figure 25. Impedance of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ sheet by heat aging time changes (a) 25℃ Impedance plot, (b) 70℃ Impedance plot 69
Figure 26. Ion conductivity of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ sheets by heat aging time changes in 70℃ 70
Figure 27. Impedance and Ion conductivity of Ga₀.₂₅Li₆.₂₅La₃Zr₂O₁₂ sheets by 70, 80, 90, and 100℃ 71
Figure 28. Coin cell (CR2032) Test of (a) charge/discharge plot, (b) C-rate, (c) Cycle test 72