표제지

국문초록

목차

약어목록 14

제1장 서론 (Introduction) 15

1.1. Components of lithium ion batteries 15

1.2. Cathode materials suitable for high energy density 17

1.2.1. Mechanism and properties of Ni-rich NCM cathode 17

1.2.2. Strategies to improve Ni-rich NCM performance 21

1.3. Anode materials suitable for high energy density 24

1.3.1. Mechanism and properties of Si-based anode 24

1.3.2. Strategies to improve Si-based anode 26

제2장 Synergistic effects of boric acid and titanium dioxide-assisted surface modification on Ni-rich LNCM 29

2.1. Introduction 29

2.1.1. Increasing the interfacial stability of Ni-rich LNCM via surface coating 29

2.2. Results and discussion 31

2.2.1. Basic physical properties of TB-based LNCM 31

2.2.2. Electrochemical properties of TB-based LNCM 34

2.2.3. Analyses of TB-based LNCM after cycling performance 37

2.3. Conclusion 43

제3장 1,1,2,2-Tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether as an Interphase Modifier for SiOₓ-based lithium-ion batteries 45

3.1. Introduction 45

3.1.1. Increasing the interfacial stability of SiOₓ via TFE additive 45

3.2. Results and discussion 46

3.2.1. The properties analyses of TFE additives 46

3.2.2. Electrochemical properties of TFE additive for SiOₓ/NCM811 electrode 50

3.2.3. Analyses of TFE additive after cycling performance 54

3.3. Conclusion 59

제4장 Reference 61

제5장 Experimental 72

5.1. TB-LNCM cathode 72

5.1.1. Manufacturing process of TB-LNCM cathode materials 72

5.1.2. Manufacturing TB-LNCM cathode and electrochemical test 72

5.1.3. Analysis of TB-LNCM cathode after cycling performance 73

5.2. TFE electrolyte additive 74

5.2.1. Manufacturing process of TFE electrolyte additive 74

5.2.2. Manufacturing SiOₓ anode slurry and electrochemical test 74

5.2.3. Analysis of SiOₓ anode post cycling performance. 75

5.2.4. Manufacturing NCM811 cathode slurry and electrochemical assessments. 75

ABSTRACT 76

Table 1.1. Characteristics of Li[NixCoyMnz]O₂ cathode materials.[이미지참조] 18

Table 1.2. Residual lithium amounts on the LiNixCoyMnzO₂ cathode materials[이미지참조] 21

Table 1.3. Comparison properties of graphite and Si-based anode. 24

Figure 1.1. Schematic illustration charge and discharge process of LIBs. 16

Figure 1.2. Layered structure of LiCoO₂ cathode materials. 17

Figure 1.3. Microcrack problems of Ni-rich NCM cathode materials. 18

Figure 1.4. Cation mixing problems of Ni-rich NCM cathode materials. 19

Figure 1.5. Surface problems of Ni-rich NCM cathode materials. 20

Figure 1.6. Electrolyte additives for Ni-rich NCM cathode materials. 22

Figure 1.7. Surface coating strategies of Ni-rich NCM cathode materials. 23

Figure 1.8. Alloy reaction mechanism of SiOₓ anode materials. 25

Figure 1.9. Pulverization, delamination, unstable SEI layer fail mechanism of SiOₓ anode. 26

Figure 1.10. Expected effect of FEC and VC electrolyte additive for SiOₓ anode. 27

Figure 2.1. Strategy and expected effect of TB coating LNCM. 29

Figure 2.2. (a) SEM images (b) TEM/EDS mapping images of LNCM and TB modified LNCM. 31

Figure 2.3. XRD spectra of the product obtained from the heat processing of LiOH, H₃BO₃ and TiO₂ precursors. 32

Figure 2.4. (a) Particle hardness values, (b) the amounts of residual lithium, (c) change in internal cell pressure and (d) XRD data of LNCM and modified TB-LNCM. 33

Figure 2.5. GITT graphs of LNCM and 0.75 TB-LNCM. 34

Figure 2.6. (a) Potential profile at 1st cycle, (b) electrochemical test of NCM half-cells at 25 ℃. (c) Potential profile at 1st cycle, (d) cycling performance of NCM half-cells at 45 ℃. DQ/dV...[이미지참조] 36

Figure 2.7. SEM images of (a) LNCM and (b) 0.75 TB-LNCM. CP-SEM images of (c) LNCM and (d) 0.75 TB-LNCM. 38

Figure 2.8. EIS results of LNCM and 0.75 TB-LNCM (a) after 10 cycles and (b) 100 cycles 39

Figure 2.9. DC-IR results of (a) LNCM and (b) 0.75 TB-LNCM 39

Figure 2.10. XPS spectra of LNCM and 75 TB-LNCM for C 1s, B 1s, Ti 2p 40

Figure 2.11. ICP-MS analyses of LNCM and 0.75 TB-LNCM for Li-metal after 100 cycles 41

Figure 2.12. Summary of TB-based LNCM coating 43

Figure 3.1. Strategy of TFE electrolyte additives for SiOₓ anode 45

Figure 3.2. Ionic conductivity of TFE-free electrolyte and 5.0 TFE, 10.0 TFE and 15.0 TFE. 47

Figure 3.3. EVS evaluation of TFE-free electrolyte and 10.0 TFE. 48

Figure 3.4. (a) XPS spectra of TFE-free electrolyte and 10.0 TFE for F 1s. (b) height and area results for LiF peak of TFE-free electrolyte and 10.0 TFE. 49

Figure 3.5. TEM images of (a) TFE-free electrolyte and (b) 10.0 TFE after formation. EDS-mapping of (c) TFE-free electrolyte and (d) 10.0 TFE. 50

Figure 3.6. Scan rate CV of (a) TFE-free electrolyte and (b) 10.0 TFE after formation. (c) initial cycle CV graph at scan rate of 0.1 mV s¯¹. (d) Peak current versus square root of scan rate and... 51

Figure 3.7. (a) Potential profile at initial cycle and (b) electrochemical performance of TFE-free electrolyte, 5.0 TFE, and 10.0 TFE at 25 ℃. (c) Potential profile at initial cycle and (d)... 52

Figure 3.8. (a) Initial coulombic efficiency and (b) average coulombic efficiency for SiOₓ half cell cycling of TFE-free electrolyte and 10.0 TFE. 53

Figure 3.9. EIS graph of TFE-free electrolyte and 10.0 TFE (a) after formation and (b) 100 cycles. 54

Figure 3.10. (a) XPS graphs for C 1s, F 1s and (b) FT-IR analysis for SiOₓ anode of TFE-free electrolyte and 10.0 TFE. 55

Figure 3.11. Cycling performance of NCM811/SiOₓ full cell (a) at 25 ℃ and (b) at 45 ℃ with TFE-free electrolyte, 5.0 TFE, and 10.0 TFE. 56

Figure 3.12. CP-SEM images for SiOₓ anode (a) pristine and (b) TFE-free electrolyte and (c) 10.0 TFE after 300 cycling at 45 ℃. TEM images and EDS-mappings of SiOₓ anode (d) - (e)... 57

Figure 3.13. SEM image of NCM811 cathode with (a) TFE-free electrolyte and (b) 10.0 TFE after 300 cycling at 45 ℃. 58

Figure 3.14. Summary of TFE electrolyte additives techniques for SiOₓ based anode. 59