Polyaniline and Polyacrylic Acid Reinforced Mechanical Strength and Conductivity at the Interface of Silicon Anodes

The poor cycling stability of silicon-based anodes in lithium-ion batteries (LIB) presents a thorny issue. We devise a strategy to regulate covalent and noncovalent interactions at the silicon-based anode interface, balancing electrode conductivity and stability. The polyaniline-poly(acrylic acid)-sodium carboxymethyl cellulose (PPC) binder is synthesized via in situ polymerization/thermal cross-linking, which utilizes the noncovalent interactions of polyaniline and the covalent interactions of O═C–O–M (Si/Cu/C) bonds to resolve the issue of asynchrony between conductivity and stability. The continuous conductive network structure formed by polyaniline, doped and gelled with 5-sulfosalicylic acid, addresses the problem of electrical connection failure in silicon-based anodes. The O═C–O–C bonds (PAA–CMC) enhance the covalent cohesion between binder molecules, preventing electrolyte swelling. The O═C–O–Si bonds enhance the covalent binding between the binder and the silicon particle interface. The covalent O═C–O–Cu bonds boost the binder–copper interface interaction, improving the interfacial stability of the entire electrode. After 1000 ultralong cycles at 1 A g–1, the nanosilicon anode with the PPC binder delivers a reversible capacity of 1130 mAh g–1. This work demonstrates a promising strategy for enhancing interfacial stability and conductivity in silicon-based anodes, offering a practical solution to improve long-term cycling performance.