A Study on Lithium Surface Stabilization in Lithium Metal Batteries Using Organic-Inorganic Composite Materials

다국어 초록 (Multilingual Abstract)

The development of lithium metal batteries faces challenges due to dendrite formation during lithium plating and stripping, causing performance degradation and safety risks. To address these issues, two strategies were adopted: achieving uniform lithium ion flux and controlling lithium nucleation. First, a composite solid electrolyte (CSE) was developed using aluminum- doped Li₇La₃Zr₂O₁₂ (Al-LLZO) nanofibers and PVDF-HFP with succinonitrile. This design provided high ionic conductivity of 3.26×10⁻⁴ S cm⁻¹ and a lithium ion transfer number of 0.78. The Li|Li symmetric cell exhibited stable overpotential for 1000 h, and the Li|LiFePO₄ full cell retained 83% capacity after 1000 cycles at 5C. Second, a MnCO₃/PVDF-HFP composite protective layer was introduced on the lithium metal surface to reduce nucleation overpotential. The MnCO₃ promoted rapid lithium ion diffusion through Mn–O bonds and facilitated the formation of Mn-rich lithiophilic site and Li₂CO₃-rich SEI layer. The Li|Cu half-cell achieved a Coulombic efficiency of 97% over 200 cycles at 1 mA cm⁻², demonstrating stable cycling. These results highlight the effectiveness of uniform lithium ion flux and controlled nucleation in suppressing dendritic growth, offering a promising strategy for enhancing the performance and safety of lithium metal batteries.

목차 (Table of Contents)

• Chapter Ⅰ. Introduction 1
• Ⅰ-1. Lithium-Metal Batteries 1
• Ⅰ-2. All-Solid-State Batteries 1
• Ⅰ-2-1. Classification of Solid-State Electrolytes 4
• Ⅰ-2-2. Ionic Conduction Mechanism of Solid State Electrolytes 7
• Ⅰ-3. Uniform Lithium-Ion Flux Control 12
• Ⅰ-3-1. Chazalviel’s Space Charge Theory 12
• Ⅰ-4. Lithium Nucleation Site Control 13
• Ⅰ-4-1. Effect of Lithiophilic Materials 13
• Ⅰ-5. References 15
• Chapter Ⅱ. Electrospun 1D Al-LLZO Incorporated PVDF- HFP Composite Electrolyte with Fast Li+ Pathway Derived from Highway-Traction Effect for High Performance Lithium Metal Batteries 25
• Ⅱ-1. Introduction 25
• Ⅱ-2. Experimental 29
• Ⅱ-2-1. Materials Preparation 29
• Ⅱ-2-2. Synthesis of Al-LLZO Nanofibers: Electrospinning 30
• Ⅱ-2-3. Synthesis of ALPHC@SN Solid Composite Electrolyte 32
• Ⅲ-2-4. Materials Characterization 34
• Ⅲ-2-5. Cell assembly and Electrochemical Measurement 35
• Ⅱ-3. Results and Discussion 37
• Ⅱ-3-1. Synthesis and Characterization of ALPHC@SN 37
• Ⅱ-3-2. Thermal and Mechanical Properties of Electrolyte 45
• Ⅱ-3-3. Ionic Conductivity and Li+ Transference Number 49
• Ⅱ-3-4. Cycling Stability of Li
• Li Symmetric Cells 52
• Ⅱ-3-5. Electrochemical Performance of Li
• ALPHC@SN
• LFP Full Cells 57
• Ⅱ-3-6. Analysis of Interfacial Stability between Lithium Metal Interface . 62
• Ⅱ-4. Summary 66
• Ⅱ-5. References 67
• Chapter Ⅲ. Interfacial Stabilization of Lithium Metal Anodes Using Lithiophilic Transition Metal Carbonates 80
• Ⅲ-1. Introduction 80
• Ⅲ-2. Experimental 84
• Ⅲ-2-1. Synthesis of MnCO3 Microsphere 84
• Ⅲ-2-2. Preparation of MnCO3/PVDF-HFP@Cu Protective Layer 85
• Ⅲ-2-3. Materials Characterization 85
• Ⅲ-2-4. Cell Assembly and Electrochemical Measurement 86
• Ⅲ-3. Results and Discussion 87
• Ⅲ-3-1. Characterization of Synthesized MnCO₃ microspheres 89
• Ⅲ-3-2. Chemical Analysis of MnCO3/PVDF-HFP@Cu 89
• Ⅲ-3-3. Electrochemical Measurement of MnCO3/PVDF-HFP@Cu 94
• Ⅲ-3-4. Analysis of SEI Layers on MnCO₃/PH@Cu electrodes 99
• Ⅲ-3-5. Analysis of lithium nucleation overpotential and Li dendrite morphology 105
• Ⅲ-4. Summary 110
• Ⅲ-5. References 111
• Chapter Ⅳ. Conclusion 119
• Ⅳ-1. Conclusion 119