Unveiling the Critical Binder Requirements for High-Energy-Density Silicon-Based Pouch Cell.

Silicon is gradually replacing graphite as a novel anode material for high-energy-density lithium-ion batteries. However, the substantial volume changes of silicon during lithiation/delithiation make the anode binder, which maintains electrode structural stability, critical for its large-scale application. Due to the internal pressure present in conventional coin cells, they cannot simulate the lower internal pressure environment of commercial pouch cells. Consequently, the practical effectiveness of silicon anode binders that perform well in coin cells is often irreproducible in commercial pouch cells. In this study, we employed commercial pouch cells to systematically investigate the impact of blended binders with different mechanical properties on the performance of silicon-based pouch cells. The results indicate that the PAH19 binder, which combines excellent mechanical fatigue resistance with a high modulus, significantly enhances the cycle life of the pouch cell and suppresses thickness expansion; after 900 cycles, the cell achieved a capacity retention of 81.7% while maintaining a thickness of 3.06 mm at full charge. This study establishes clear performance requirements for commercial silicon-based anode binders and offers valuable guidance for the future large-scale commercial application of silicon anodes.