Engineering self-adaptive composite binders for micron-sized SiOx in lithium-ion battery anodes

High-capacity silicon-based anodes in lithium-ion batteries face significant challenges due to substantial volume changes and low initial Coulombic efficiency, which hinder their commercialization. While optimizing the intrinsic properties of the active material is essential, the binder plays a crucial role in enhancing the cycling stability and Coulombic efficiency of silicon-based anodes. In this study, we present a novel three-dimensional network composite binder developed through a soft-hard combination strategy. This binder features the natural elastic supramolecule guar gum (GG), rich in hydroxyl groups, which is crosslinked to a linear rigid polymer polyacrylic acid (PAA) backbone via hydrogen bonding. Leveraging its exceptional self-adaptive capability, the GG-PAA composite binder significantly improves the efficiency and durability of the anode composed of commercial micron-sized SiO_x, achieving an initial Coulombic efficiency of 75.09 % and retaining a capacity of 882.2 mAh g⁻¹ after 150 cycles at 1.0 A g⁻¹. This work offers a viable strategy for designing self-adapting binders for silicon-based anode applications.