Sodium 4-Vinylbenzenesulfonate as an Interface Stabilizing Additive for Silicon/Graphite Composite Anodes

다국어 초록 (Multilingual Abstract)

Incorporating silicon into graphite-based （Si/Gr） blended anodes raises energy density well beyond the theoretical capacity limit of graphite alone, yet persistent capacity fade under prolonged cycling remains the central obstacle to practical adoption. Two mutually reinforcing degradation mechanisms drive this limitation. Spatially uneven lithium-ion distribution across the electrode thickness concentrates ionic current at discrete reaction sites and drives heterogeneous lithiation, while the large volumetric expansion of silicon during each charge cycle repeatedly fractures the solid electrolyte interphase before a stable passivation layer can develop. This work introduces sodium 4-vinylbenzenesulfonate （SVBS）, a multifunctional molecular additive incorporated into the Si/Gr slurry at 0.5 wt% without altering the conventional electrode fabrication sequence. The aromatic ring of SVBS binds to graphite surfaces through 𝜋 − 𝜋 interaction, while the sulfonate group （–SO3 anchors anionic charge directly at the particle surface. Immobilizing the anions in this manner raises the lithium transference number from 0.198 to 0.586, alleviating concentration polarization under fast charge conditions and establishing a spatially homogeneous lithium-ion flux throughout the electrode. The regulated ionic environment induces interphase formation toward an inorganic-dominant composition enriched in LiF, which is mechanochemically resilient and suppresses continued electrolyte decomposition throughout long-term cycling. The surface fixed anionic charges additionally disperse silicon agglomerates through electrostatic repulsion during slurry mixing, improving electrode cohesion by 28% and adhesion by 23% while reducing post-cycling electrode swelling from 62.8% to 31.1%. In half-cell evaluations, the SVBS anode retained 77.7% of its initial capacity over 100 cycles, compared with 68.1% for the pristine anode. Full-cells pairing the SVBS anode with an NCM811 cathode achieved a capacity retention ratio of 51.0% over 300 cycles at 1C against 35.8% for the pristine anode, with an average coulombic efficiency of 99.8%. These results demonstrate that a single slurry additive can simultaneously govern electrode microstructure, ionic transport and interphase chemistry, offering a practical and scalable pathway to high-energy-density Si/Gr blended anodes with improved cycle life.

목차 (Table of Contents)

• CHAPTER 1. Introduction 1
• CHAPTER 2. Experimental methods 8
• 2.1 Preparation of electrodes 8
• 2.2 Materials characterization 8
• 2.3 Cell fabrication and electrochemical testing 9
• 2.4 Computational details 11
• CHAPTER 3. Results and discussion 13
• 3.1 SVBS additive design and electrode physicochemical properties 13
• 3.2 Li⁺ transport kinetics and interfacial characterization 15
• 3.3 Electrochemical performance and morphological stability 22
• 3.4 Full-cell electrochemical characterization 27
• CHAPTER 4. Conclusions and future directions 33
• 4.1 Conclusions 33
• 4.2 Research limitations and future directions 34
• References 35
• 국문초록 39
• 국문초록 41