Slurry Additive Approach Enables a Mechanically Robust Binder for Silicon–Carbon Anodes in Lithium-Ion Batteries

Silicon-carbon (Si/C) composites hold great promise as substitutes for conventional graphite anodes in high-specific-energy lithium-ion batteries (LIBs). However, their performance is hindered by silicon's substantial volume expansion during cycling, which can lead to electrode degradation. Traditional poly(acrylic acid) (PAA) binders often struggle to maintain electrode integrity under these conditions. To address this challenge, polyether modified polyurethane acrylic (PUMA) is used as physicochemical cocrosslinking polymer. PUMA offers superior mechanical properties, elasticity, and interfacial stability, enabling it to effectively accommodate silicon's volume changes and prevent electrode fracture. Through a simple preparation process, we used PUMA as a slurry additive in combination with PAA to form a functional composite binder, facilitating the construction of a stable and robust SEI film. This is conducive to alleviating the volume expansion of silicon and ensuring the cycling stability of the electrode. In Si/C450 half-cells, electrodes enhanced by our binder show a remarkable longevity, maintaining 97.26% of their capacity post 200 cycles at 0.5 C. The full cells Si/C450||NCM811 display a notable performance, achieving a capacity retention of 82.10% after 100 cycles at 0.2 C. These findings underscore the potential of our innovative binder design in enhancing the efficacy of silicon-based anodes in high-energy LIBs.