Advanced Cathode and Interfacial Engineering for High-performance Lithium-ion and Lithium-metal Batteries

다국어 초록 (Multilingual Abstract)

At the forefront of modern energy storage, rechargeable lithium-ion batteries (LIBs) enable the widespread adoption of largescale grid energy storage technologies, electric vehicles and portable electronics. However, LIBs encounter significant challenges associated with cathode instability, limited capacity and energy density, electrolyte decomposition, and uncontrolled interfacial reactions. To surpass these limitations, lithium-metal batteries (LMBs) have gained prominence as a potential alternative; yet, this shift brings its own critical obstacles, notably the severe issues associated with the highly reactive Li-metal anode: uncontrolled interfacial reactions, dendritic growth, and extensive electrolyte decomposition. Addressing these issues requires a dual approach: engineering high-capacity cathode materials with structural stability and designing interfacial strategies to suppress side reactions and ensure safe cycling.
This dissertation focuses on advanced cathode design and interfacial engineering for next-generation Li-based batteries, integrating experimental synthesis, electrochemical analysis, and computational simulations. First, carbon-decorated hydrated vanadium oxide-based nanorods (V10O24·nH2O/C) were prepared via a simple hydrothermal method, delivering superior capacity and stability owing to expanded interlayer spacing, conductive carbon coating, and water-stabilized structures. Building on this, Fe-doped, and Li3PO4 and C double coated Li3V2(PO4)3 cathode active material composite was developed using sol–gel assisted hydrothermally process, achieving enhanced conductivity, capacity retention, and full-cell stability through synergistic effects of doping, surface coating, and carbon engineering. These cathode-centered advancements highlight the promise of structural and compositional tuning for durable LIB electrodes.
Complementing cathode innovations, this work explores electrolyte and interfacial design for LMBs. Through computational methods, encompassing density functional theory and molecular dynamics, co-additives such as urea and acetamide were shown to markedly improve lithium nitrate (LiNO3) solubility in carbonate electrolytes, restructure Li+ solvation environments, and suppress LiPF6 decomposition. Guided by these insights, experimental validation with urea–LiNO3 co-additive electrolytes demonstrated stable Li||Li and Li||NMC811 cells, achieving extended cycling stability and improved efficiency. Together, these findings establish a framework where cathode engineering and interfacial stabilization converge to enable high-performance LIBs and LMBs. The results provide not only fundamental insights but also scalable strategies for advancing sustainable, safe, and energy-dense battery technologies.

목차 (Table of Contents)

• CHAPTER 1. General Introduction １
• 1.1 Energy Demand and Landscape １
• 1.1.1 Role of Energy Storages １
• 1.1.2 Overview of Energy Storage Technologies １
• 1.1.3 The Preeminence of Lithium-Based Batteries １
• 1.2 Fundamentals of Li-Based Batteries ３
• 1.2.1 Operating Mechanisms ３
• 1.2.2 Next-Generation LMBs ３
• 1.2.3 Critical Performance Metrics ４
• 1.3 Key Components and Characterization ５
• 1.3.1 The Energy Density Bottleneck: Cathode Active Materials ５
• 1.3.2 Anode Materials: Transition from Intercalation to Plating/Stripping ６
• 1.3.3 The Electrolyte, Additives and SEI Layer ７
• 1.3.4 Essential Electrochemical Techniques ８
• 1.3.5 Structural and Interfacial Characterization Tools ８
• 1.4 Current Status and Major Challenges ８
• 1.4.1 Challenges in High-Performance Cathode Engineering ８
• 1.4.2 The Interfacial Crisis of Li-metal Batteries ９
• 1.4.3 The Critical Role of Additive-Engineered Electrolytes ９
• 1.4.4 Thesis Scope and Organization ９
• CHAPTER 2. Carbon-coated Hydrated V10O24 Nanorods for Improved Li-ion Cathodes １１
• 2.1 Introduction and Context １１
• 2.1.1 General Background １１
• 2.1.2 Problem Statement １１
• 2.1.3 Literature Reviews １２
• 2.1.4 Study Objectives １４
• 2.2 Experimental １４
• 2.2.1 Materials Synthesis and Preparation １４
• 2.2.2 Characterizations １５
• 2.2.3 Electrochemical Testing １６
• 2.3 Results and Discussion １７
• 2.3.1 Morphology and Structure １７
• 2.3.2 Electro-chemical Performances ２１
• 2.3.3 Comparison with Literature ２７
• 2.4 Conclusions ２９
• 2.4.1 Key Findings ２９
• 2.4.2 Link to the Next Chapter ３０
• CHAPTER 3. Synergistic Effects of Li3PO4 Coating and Fe-doping on Li3V2(PO4)3/C for Enhanced Lithium-ion Storage ３１
• 3.1 Introduction and Context ３１
• 3.1.1 General Background ３１
• 3.1.2 Specific Problem Statement ３１
• 3.1.3 Focused Literature Review ３２
• 3.1.4 Study Objectives ３４
• 3.2 Experimentation ３５
• 3.2.1 Materials Preparations ３５
• 3.2.2 Characterization Techniques ３６
• 3.2.3 Electrochemical Cell Assembly and Testing ３６
• 3.3 Results and Discussion ３７
• 3.3.1 Microscopic and Structural Analysis ３７
• 3.3.2 Electro-chemical Performances ４４
• 3.3.3 Comparison with Literature ５０
• 3.4 Conclusions ５２
• 3.4.1 Key Findings ５２
• 3.4.2 Link to the Next Chapter ５３
• CHAPTER 4. Molecular Mechanisms of Co-Additive-Assisted LiNO3 Solubilization for Stable Lithium Metal Batteries ５５
• 4.1 Introduction and Scientific Context ５５
• 4.1.1 Fundamental Concepts and Background ５５
• 4.1.2 Specific Problem Statement ５５
• 4.1.3 Literature Review ５６
• 4.1.4 Objectives of This Study ５７
• 4.2 Experimentation ５９
• 4.2.1 Preparation of Materials ５９
• 4.2.2 Material Characterizations ５９
• 4.2.3 Electrochemical Cell Assembly and Testing ６０
• 4.2.4 Computational Methods ６１
• 4.3 Results and Discussion ６３
• 4.3.1 Quantum Chemical (DFT) Calculations ６３
• 4.3.2 MD Simulations Results ７８
• 4.3.3 Experimental Investigations and Results ８６
• 4.4 Summary and Conclusions １００
• 4.4.1 Summary of Key Findings. １００
• 4.4.2 Link to the Next Chapter １０２
• CHAPTER 5. Overall Discussion, Key Conclusions, and Future Directions １０３
• 5.1 Chapter Overview １０３
• 5.2 Integrated Discussion of Key Findings １０３
• 5.2.1 Hierarchical Vanadium Oxides (V₁₀O₂₄·nH₂O/C) １０３
• 5.2.2 Fe-Doped Li₃V₂(PO₄)₃–Li₃PO₄/C Composites. １０４
• 5.2.3 Computational Insights on LiNO3 Solubilization １０５
• 5.2.4 Experimental Validation of Urea as a LiNO3 Solubilizer １０５
• 5.3 Multi-Scale Design Framework １０５
• 5.4 General Conclusions １０６
• 5.5 Future Perspectives １０７
• 5.6 Closing Remarks １０７
• Acknowledgements １０８
• References １０９
• Appendices １２２
• 국문초록 １２６