Title Page
Abstract
Contents
CHAPTER 1. Introduction 12
CHAPTER 2. Experimental 15
2.1. Materials and Reagents 15
2.2. Recycling of Degraded NCM Materials 15
2.3. Physical Characterization 16
2.4. Cell Assembly and Electrochemical Measurement 17
CHAPTER 3. Results and Discussion 19
3.1. Electrochemical delamination of NCM from spent cathode 19
3.2. Regeneration of degraded NCM and electrochemical performances 33
CHAPTER 4. Conclusion 48
References 50
Table 1. ICP-OES results of electrolytes before and after process iteration 32
Table 2. Results of Rietveld refinement of RNCM, SNCM and CNCM. 37
Table 3. ICP-OES results of RNCM, SNCM and CNCM. 47
Table 4. Resistance and diffusion coefficient values of RNCM, RNCM-2nd, SNCM and CNCM.[이미지참조] 47
Figure 1. Capacity retention rate of commercial cylindrical 18650 LIB at 2.0 C (1 C=2500 mA g⁻¹). 20
Figure 2. Schematical illustration for the electrochemical exfoliating process under (a) DC and (d) AC conditions. Current density-time profiles and pH... 23
Figure 3. Photographs showing the treated electrode for the following conditions: (a) DC conditions, (b) AC conditions with four-times-alternation for each holding... 24
Figure 4. (a) Scanning electron microscopy (SEM) image of aluminum current collector after electrochemical exfoliating process. Energy dispersive X-ray... 24
Figure 5. SEM images of NCM particles after annealing process without delamination process. 25
Figure 6. SEM images of spent electrode after the exfoliation process: (a) and (b) anode and (c) and (d) cathode under DC conditions, (e) and (f) electrode under... 26
Figure 7. Photographs showing the treated electrodes for the following areas: (a) 2×2 cm², (b) 3×3 cm², (c) 4×4 cm². (d) Current density-time profiles for various... 29
Figure 8. Photographs showing the (a) electrolyte changes and (b) current density profile changes according to the number of processes. 31
Figure 9. (a) X-ray diffraction pattern (XRD) of suspended matter. (b) Thermogravimetric analysis (TGA) curve of suspended matter. 31
Figure 10. Photograph showing the treated electrode of 17th and 18th iteration.[이미지참조] 32
Figure 11. High-resolution transmission electron microscopy (HR-TEM) images and fast Fourier transform (FFT) patterns of (a) SNCM and (b) RNCM. (c) X-ray... 36
Figure 12. HR-TEM images and FFT patterns of CNCM. 37
Figure 13. X-ray photoelectron spectroscopy (XPS) results for SNCM and RNCM: (a) Ni 2p spectra and (b) contribution of Ni species determined by Ni 2p... 39
Figure 14. Cycle performance of RNCM-H and RNCM-S at 0.2 C (1 C=150 mA g⁻¹). 41
Figure 15. Electrochemical performances of CNCM, SNCM and RNCM. Voltage profiles of (a) RNCM, (b) SNCM, and (c) CNCM for the first to second cycle in... 45
Figure 16. Nyquist plot of RNCM-2nd.[이미지참조] 46
Figure 17. Graphs depicting Z' in relation to ω-1/2 within the low-frequency range. 46
Scheme. Schematical illustration for direct recycling process of spent NCM523. 19