Optimizing the Chain Arrangement of Styrene Butadiene Rubber Enables a High-Performance Aqueous-Based Binder in Lithium-Ion Batteries

For the development of environmentally sustainable and cost-effective manufacturing processes in the lithium-ion battery industry, the adoption of aqueous-based binders holds significant promise. To date, the combination of styrene butadiene rubber (SBR) emulsion and carboxymethyl cellulose sodium (CMC) remains the most widely utilized binder system in anode fabrication owing to its strong adhesion and excellent mechanical properties. However, the concentrated and entangled SBR chains fail to provide sufficient space for the embedding of adjacent CMC molecules, resulting in high isolating characteristics and heterogeneous dispersion between the two components. Herein, a coupling reaction for SBR (SBRS) is conducted using dichlorodimethoxysilane as the coupling reagent to optimize the chain distribution. This reaction promotes the ordered arrangement of SBR chains and CMC molecules, while the formed coupling network further enhances the uniformity and structural integrity of the binder. Leveraging these advantages, the graphite-Li half-cell prepared with SBRS+CMC delivers discharge capacities of 351 and 226 mAh g–1 at current rates of 0.1 and 0.6C, respectively, along with a capacity retention rate of ∼60% after 90 cycles and a decent rate capability. The performance of the SBRS+CMC half-cell is superior to that of the SBR+CMC half-cell. This work thus presents an efficient strategy for designing high-performance aqueous-based binders for lithium-ion batteries.