A Synergistic Dual Architecture : Bridging Internal Voids of Micro-sized Porous Silicon with Conformally Wrapped rGO Networks for Durable Lithium Storage Anodes

다국어 초록 (Multilingual Abstract)

Silicon is attracting attention as a next-generation lithium-ion battery anode material due to its high theoretical capacity （4200 mAh g-1）. However, extreme volume expansion during the cycling process causes particle fragmentation and the continuous formation of an unstable solid electrolyte interphase （SEI） layer, leading to a rapid decrease in capacity. In this study, a mesoporous silicon composite covalently anchored rGO nanosheets （mPSi@rGO） was developed to address these issues. This structure is obtained by maintaining an internal porous framework of mPSi while uniformly wrapping the mPSi surface with a reduced graphene oxide （rGO） network through strong covalent bonding. The internal pores effectively accommodate volume expansion and facilitate rapid lithium-ion transport. At the same time, the wrapped rGO network significantly enhances the electrical conductivity of silicon particles, while providing mechanical restraint, and maintaining electrical connectivity within the particles even if internal fragmentation occurs.
Electrochemical evaluation results showed that the mPSi@rGO electrode achieved a high initial discharge capacity of 3638 mAh g-1 and an initial Coulombic efficiency of 87.37%. In particular, it maintained an excellent reversible capacity of 3219 mAh g-1 after 50 cycles at a current density of 0.5 A g-1 and recorded a high capacity retention rate of 87.96% even after 100 cycles, demonstrating superior stability compared to pristine mSi and mPSi. Furthermore, it exhibited an excellent rate capability performance by achieving a high discharge capacity of 1357 mAh g-1 even at a high current density of 4.0 A g-1. These results suggest that the dual-structure hierarchical design of mPSi@rGO composite effectively stabilizes the SEI layer and prevents irreversible lithium-ion loss, presenting a scalable paradigm for the commercialization of high-energy-density silicon-based batteries.

목차 (Table of Contents)

• CHAPTER 1. Introduction 1
• 1.1 An overview of Li-ion batteries and Si anodes 1
• 1.2 Literature Reviews 5
• 1.3 Research trends & objectives 14
• 1.3.1 Limitations of the existing silicon anode research paradigm 14
• 1.3.2 Strategy for reconciling structural stability and energy density 15
• CHAPTER 2. Material and Method 18
• 2.1 Chemical materials 18
• 2.2 Experiment methods 18
• 2.2.1 Synthesis of porous mSi samples (mPSi) 18
• 2.2.2 Piranha solution treated porous mSi (mPSi-OH) 21
• 2.2.3 APTES aminated porous mSi (mPSi-NH2) 23
• 2.2.4 Graphene oxide-coated mPSi (mPSi@GO) 25
• 2.2.5 Preparation of mPSi@rGO composite 27
• 2.2.6 Li-ion batteries 29
• 2.3 Analyses 30
• 2.3.1 Scanning Electron Microscopy (SEM) 30
• 2.3.2 Transmission Electron Microscope (TEM) 30
• 2.3.3 X-ray Diffraction (XRD) 30
• 2.3.4 X-ray Photoelectron Spectroscopy (XPS) 30
• 2.3.5 Raman spectroscopy 31
• 2.3.6 Brunauer Emmett Teller (BET) 31
• 2.3.7 Thermogravimetric Analysis (TGA) 31
• 2.3.8 Electrochemical instrument 31
• CHAPTER 3. Results and Discussion 34
• 3.1 Characterization of as-prepared mPSi@rGO samples 34
• 3.1.1 SEM 34
• 3.1.2 HR-TEM & EDS 36
• 3.1.3 XRD 39
• 3.1.4 XPS 41
• 3.1.5 Raman 45
• 3.1.6 BET 47
• 3.1.7 TGA 51
• 3.2 Electrochemical properties and performance 53
• 3.2.1 Cyclic voltammetry 53
• 3.2.2 Cyclic performance 57
• 3.2.3 Post-cycling analysis of the anodes 62
• 3.3 Plausible mechanism for improved performance 64
• CHAPTER 4. Conclusion 67
• References 68
• 국문초록 73