Title Page
Abstract
Contents
Chapter 1. Introduction 17
1.1. General introduction 17
1.2. Objectives and outline of the thesis 22
Chapter 2. Role of carboxymethyl cellulose binder and its effect on the preparation process of anode slurries 24
2.1. Introduction 24
2.2. Experimental section 28
2.2.1. Materials 28
2.2.2. Sample preparation 28
2.2.3. Rheological characterization 29
2.2.4. Adsorption isotherm 29
2.2.5. Microstructure observation 30
2.3. Results and discussion 31
2.3.1. Role of CMC binder in the anode slurry 31
2.3.2. Effect of the preparation process on the slurry dispersion with respect to CMC content 44
2.4. Conclusion 60
Chapter 3. Significant agglomeration of conductive materials and dispersion state change of Ni-rich NMC cathode slurries during storage 64
3.1. Introduction 64
3.2. Experimental section 67
3.2.1. Materials 67
3.2.2. Sample preparation 67
3.2.3. Rheological characterization 71
3.2.4. Microstructure observation 72
3.3. Results and discussion 73
3.3.1. Significant changes in rheological properties and microstructure of cathode slurries during storage 73
3.3.2. Effect of agitation speed on the rheological properties of cathode slurry during storage 77
3.3.3. Effect of matrix viscosity on the rheological properties of cathode slurry during storage 80
3.3.4. Changes in rheological properties and dispersion state of cathode slurry due to hydrodynamic stress 84
3.4. Conclusion 96
Chapter 4. Rheological behavior and microstructure formation of Si/CB anode slurries 100
4.1. Introduction 100
4.2. Experimental section 103
4.2.1. Materials 103
4.2.2. Sample preparation 103
4.2.3. Rheological characterization 104
4.2.4. Microstructure observation 105
4.3. Results and discussion 106
4.3.1. CB/CMC and Si/CMC suspensions 106
4.3.2. Si/CB suspension 115
4.3.3. Si/CB/CMC anode slurry 121
4.4. Conclusion 132
Chapter 5. Concluding remarks 135
Bibliography 139
Abstract (Korean) 151
Figure 1.1. Schematic of the electrode preparation process. 17
Figure 1.2. (a) Steady shear viscosity and (b) frequency dependent storage (G') and loss (G'') modulus of NCM/CB/PVDF/NMP cathode... 19
Figure 1.3. G' (closed symbol) and G'' (open symbol) of 50 wt% graphite slurry as a function of frequency with increasing (a) CMC... 21
Figure 2.1. Storage (closed symbol) and loss (open symbol) modulus of (a) 5 wt% CB suspensions and (b) 45 wt% graphite suspensions... 31
Figure 2.2. Relative viscosity curves of (a) 3 wt% CB suspensions, and (b) 45 wt% graphite suspensions with varying CMC content. 33
Figure 2.3. Adsorption isotherm of (a) CB-CMC and (c) graphite-CMC. Viscosity (shear rate=1 s⁻¹) of (b) 3 wt% CB and (d) 45... 35
Figure 2.4. (a) frequency sweep results of the CMC solution with varying CMC content. (b) Tan(𝛿)=G''/G' at frequency=1 rad/s... 38
Figure 2.5. Optical micrographs of 5 wt% CB suspensions with (a) no CMC, (b) CMC 0.2 wt% (below optimum graft density), and (c) CMC... 40
Figure 2.6. (a) Storage and loss modulus of the anode slurries (graphite 36 wt%, CB 1.8 wt%) at frequency=1 rad/s with varying... 41
Figure 2.7. Optical micrographs of the anode slurries (graphite 36 wt%, CB 1.8 wt%) with (a) no CMC (b) CMC 0.2 wt% (below optimum... 43
Figure 2.8. Images of the anode slurries (graphite 36 wt%, CB 1.8 wt%) with varying CMC content. 44
Figure 2.9. Three anode slurry preparation processes with different mixing sequence of CMC and the two particles (graphite, CB).... 45
Figure 2.10. CMC content (0.13 wt%) lower than the optimum graft density; (a) Storage and loss modulus of P1C, P1G, P2C, and P2G at... 47
Figure 2.11. Optical micrographs of the (a) P1C, (b) P2C, (c) P1G, and (d) P2G when the CMC content (0.13 wt%) is lower than the... 48
Figure 2.12. CMC content (0.13 wt%) lower than the optimum graft density. Optical micrographs of the anode slurries; (a, b) P1 slurry,... 49
Figure 2.13. Storage and loss modulus (circular symbol, at frequency=1 rad/s), and yield stress (diamond symbol) of P1'(graphite 36... 52
Figure 2.14. CMC content (1.9 wt%) higher than the optimum graft density; (a) Storage and loss modulus of P1C, P1G, P2C, and P2G at... 53
Figure 2.15. Optical micrographs of the (a) P1C, (b) P2C, (c) P1G, and (d) P2G when the CMC content (1.9 wt%) is higher than the... 55
Figure 2.16. CMC content (0.13 wt%) higher than the optimum graft density. Optical micrographs of the anode slurries; (a, b) P1 slurry,... 56
Figure 2.17. Schematic of the mechanism of the slurry microstructure change according to the CMC mixing sequence. 57
Figure 2.18. (a) Storage modulus (frequency=1 rad/s), and (b) viscosity (shear rate=1s⁻¹) of the anode slurries according to the... 59
Figure 2.19. Schematic of the role of CMC and how it affects the slurry preparation process. 60
Figure 3.1. Schematic diagram of storage tank and stirrer with dimensions. 69
Figure 3.2. (a) Image of the slurry sampled after 3 hours of storage in a storage tank (b) slurry density as a function of tank height. 70
Figure 3.3. Storage (closed symbol) and loss (open symbol) modulus of cathode slurry (NMC 25 vol%, AB 1.5 vol%, PVDF 2.5 wt%) as a... 73
Figure 3.4. Optical microscopic images of cathode slurry(NMC 4.2 vol%, AB 1.25 vol%, PVDF 4.2 wt%): (a) & (b) right after mixing, (c)... 74
Figure 3.5. FE-SEM surface images of cathode (NMC 95.7 wt%, AB 2.7 wt%, PVDF 1.6 wt%): (a) & (c) right after mixing, (b) & (d)... 76
Figure 3.6. Storage (closed symbol) and loss (open symbol) modulus of cathode slurry (NMC 25 vol%, AB 1.5 vol%, PVDF 2.5 wt%) as a... 77
Figure 3.7. Storage modulus (G') of cathode slurry (at angular frequency=1 rad/s) as a function of total strain during storage at... 78
Figure 3.8. Flow curves of (a) PVDF (700K) solution, and (b) PVDF (320K) solution. 80
Figure 3.9. Storage (closed symbol) and loss (open symbol) modulus of cathode slurry (NMC 25 vol%, AB 1.5 vol%) as a function of... 80
Figure 3.10. Rotational speed dependence of storage modulus (at angular frequency=1 rad/s) of the cathode slurries (NMC 25 vol%,... 82
Figure 3.11. Storage modulus (at angular frequency=1 rad/s) of the cathode slurries (NMC 25 vol%, AB 1.5 vol%, PVDF(700K) 2.5, 3.5,... 84
Figure 3.12. Optical micrographs of cathode slurries (NMC 4.2 vol%, AB 0.25 vol%) after 3 hours agitation at each stress conditions: (a)... 88
Figure 3.13. Changes in rheological properties of (a) NMC/AB/PVDF cathode slurry, and (b) graphite/AB/PVDF anode slurry after storage... 90
Figure 3.14. Changes in microstructure of (a) NMC/AB/PVDF cathode slurry, and (b) graphite/AB/PVDF anode slurry after storage... 90
Figure 3.15. Agglomerate (particle) size distribution by image processing of optical microscopic images of cathode slurries: (a)... 92
Figure 3.16. (a) Peak hold test results of cathode slurries (NMC 25 vol%, AB 1.5 vol%, PVDF (700K) 2.5 wt%) at γ̇=20s⁻¹ (τ=0.8 Pα)...[이미지참조] 94
Figure 3.17. Schematic of the changes in rheological properties and microstructure of the cathode slurry during storage according to the... 96
Figure 3.18. FE-SEM surface images of cathode (NMC 95.7 wt%, AB 2.7 wt%, PVDF 1.6 wt%) prepared from the cathode slurry stored... 99
Figure 4.1. (a) frequency sweep results and (b) plateau modulus (at angular frequency=1 rad/s) of CB suspension (CB/water) with... 106
Figure 4.2. (a) storage modulus (G') and (b) loss modulus (G'') of 5 wt% CB suspension with varying CMC content as a function of angular... 108
Figure 4.3. (a) adsorption isotherm of CMC-CB and CMC-Si. (b) Viscosity (shear rate=0.1 s⁻¹, closed symbol, left) and tan(𝛿)=... 109
Figure 4.4. Optical micrographs of 5 wt% CB suspensions with (a) no CMC, (b) CMC 0.2 wt% (below optimum graft density), (c) CMC 1.0... 112
Figure 4.5. Optical micrographs of 30 wt% Si suspension with (a) no CMC, (b) CMC 0.2 wt%, (c) CMC 1.0 wt%, and (f) CMC 2.0 wt%.... 113
Figure 4.6. Images of the (a) 5 wt% CB suspension, and (b) 30 wt% Si suspension with varying CMC content. 115
Figure 4.7. (a) Storage modulus (frequency=1 rad/s), and (b) viscosity (shear rate=0.1 s⁻¹) of Si and Si/CB suspensions with... 115
Figure 4.8. Optical micrographs of Si/CB suspension containing (a) CB 0.23 vol%/Si 2 vol%, (b) CB 0.23 vol%/Si 5 vol%, (c) CB 0.23... 117
Figure 4.9. Optical micrographs of Si/CB suspension containing (a) CB 2.3 vol%/Si 2 vol%, (b) CB 2.3 vol%/Si 5 vol%, (c) CB 2.3 vol%/Si... 118
Figure 4.10. (a) Storage modulus (frequency=1 rad/s), and (b) viscosity (shear rate=0.1 s⁻¹) of CB and Si/CB suspensions with... 120
Figure 4.11. Storage modulus of Si/CB/CMC anode slurry containing Si 15 vol% with (a) no CMC, (b) CMC 0.5 wt%, (c) CMC 1.0 wt%... 121
Figure 4.12. Rheological properties of Si/CB/CMC anode slurries containing Si 0/2/15 vol% and CB 2.3 vol% with varying CMC content:... 123
Figure 4.13. Optical micrographs of Si/CB/CMC anode slurry containing Si 15 vol% and CB 2.3 vol% with increasing CMC content:... 126
Figure 4.14. Optical micrographs of Si/CB/CMC anode slurry containing Si 2 vol% and CB 2.3 vol% with increasing CMC content:... 128
Figure 4.15. Optical micrographs of Si/CB/CMC anode slurry containing Si 15 vol% and CB 2.3 vol% with (a) CMC 2.0 wt%, (b)... 129
Figure 4.16. Viscosity (shear rate=0.1 s⁻¹, closed symbol, left) and tan(𝛿)=G''/G' (frequency=1 rad/s, red symbol, right) of Si/CB... 130
Figure 4.17. Schematic of the rheological behavior and microstructure formation of the Si/CB/CMC anode slurries. 132