Title Page
Contents
Abstract 10
Chapter 1. INTRODUCTION 12
1.1. Limitation of Lithium-Ion Battery 12
1.2. Solid electrolyte types for Lithium-Ion batteries 17
1.3. Garnet-type Li7la3Zr2O12 electrolyte[이미지참조] 23
Chapter 2. EXPERIMENT 26
2.1. Synthesis of Pristine Li7La3Zr2O12 with a heating rate 5 ℃/min[이미지참조] 26
2.2. Synthesis of Li7-xAlxLa3Zr2O12 with a heating rate of 5℃/min(x=0.25, 0.5, 0.75, 1, 1.25)[이미지참조] 29
2.3. Sample Characterization 32
Chapter 3. Results and discussion 33
3.1. Ionic Conductivity and EDS analysis of Pristine Li7La3Zr2O12[이미지참조] 33
3.2. Ionic Conductivity and EDS analysis of Al-doped Li7La3Zr2O12[이미지참조] 44
1) stabilization of cubic phase Li7-xAlxLa3Zr2O12 by adding Al mole ratio at 1100℃[이미지참조] 44
2) stabilization of cubic phase Li7-xAlxLa3Zr2O12 by adding Al mole ratio at 1200 ℃[이미지참조] 49
3) stabilization of cubic phase Li7-xAlxLa3Zr2O12 by adding Al mole ratio at 1000 ℃[이미지참조] 54
4) Comparison of Pristine LLZO and Al-LLZO optimized for each temperature 59
Chapter 4. Conclusion 61
References 63
논문요약 67
Table 1-1. Summary of lithium-ion solid electrolyte materials 20
Table 3-1. Total resistance of pristine LLZO and ionic conductivity. 42
Table 3-2. Total resistance of Al-LLZO calcined for 24h at 1100℃ and ionic conductivity. 48
Table 3-3. Total resistance of Al-LLZO calcined for 24h at 1200℃ and ionic conductivity. 53
Table 3-4. Total resistance of Al-LLZO calcined for 24h at 1200℃ and ionic conductivity. 58
Figure 1-1. Energy densities of the standard cylindrical 18650 LIB cells (with a... 14
Figure 1-2. Three stages for the thermal runaway process. 16
Figure 1-3. Performance of different solid electrolyte materials. 18
Figure 1-4. Ionic conductivities of solid electrolytes are shown in comparison to... 19
Figure 1-5. (a) Three-dimensional network structure of the Li atomic arrangement in... 25
Figure 2-1. A schematic diagram of the LLZO synthesis process, Black Line :... 28
Figure 2-2. A schematic diagram of the Al-LLZO synthesis process, Black Line :... 31
Figure 3-1. XRD data of LLZO Synthesis preliminary experiment (heating rate... 36
Figure 3-2. TG/DTA curves of (a) LiOH·H₂O precursor and (b) LLZO mixture.... 37
Figure 3-3. TG curves of the mixed raw materials 38
Figure 3-4. 3 types of crucibles used during heat treatment and the presence or... 39
Figure 3-5. XRD data of 3 types of crucibles used during heat treatment and the... 40
Figure 3-6. XRD data of pristine LLZO. (from the bottom,) last heat treatment... 41
Figure 3-7. Nyquist plot and equivalent of pristine LLZO under the conditions of... 42
Figure 3-8. (a) Cross-sectional SEM image of pristine LLZO pellet fracture surface... 43
Figure 3-9. XRD data of Al-LLZO calcined for 24h at 1100℃ (from the top)... 46
Figure 3-10. Nyquist Plot of Al-LLZO calcined for 24h at 1100℃ (a) x= 0.25 (b) x=... 47
Figure 3-11. (a) Cross-sectional SEM image of 0.75 Al-LLZO pellet fracture... 48
Figure 3-12. XRD data of Al-LLZO calcined for 24h at 1200℃ (from the top)... 51
Figure 3-13. Nyquist Plot of of Al-LLZO calcined for 24h at 1200℃ (a) x= 0.25 (b) x=... 52
Figure 3-14. (a) Cross-sectional SEM image of 0.25 Al-LLZO pellet fracture... 53
Figure 3-15. XRD data of Al-LLZO calcined for 24h at 1200℃ (from the top)... 56
Figure 3-16. Nyquist Plot of Al-LLZO calcined for 24h at 1200℃ (a) x= 0.5 (b) x=... 57
Figure 3-17. (a) Cross-sectional SEM image of 1.25 Al-LLZO pellet fracture surface... 58
Figure 3-18. cross-sectional images of pristine LLZO and Al-LLZO optimized for... 60
Figure 3-19. Ionic conductivity characteristics for each molar ratio 60