A Multifunctional Polymer Binder for High-Performance Si/C Anodes in Lithium-Ion Batteries

Conventional poly(acrylic acid) binders are unable to satisfy the rigorous criteria for silicon anodes, which impedes the progress of high-energy-density lithium-ion batteries. Therefore, it is essential to design a binder capable of withstanding the volumetric impact and low electrical conductivity of Si-based anodes. In this study, a multifunctional binder, named the PODA binder, with a 3D polymer network structure was proposed to achieve enhanced mechanical properties and improved electronic and ionic conductivity based on amide bonds, phenyl ether bonds, and π–π interactions, effectively preserving the completeness of the Si anodes. The phenyl ether group facilitated rapid Li+ and electron transport, establishing efficient conduction pathways within the binder. The PODA binder successfully maintained the structural integrity and mitigated the volumetric expansion of the silicon-carbon anode electrodes. At 2 A g–1, enabled by the binder, the Si-C anode achieved superior specific charge capacity retention of ≈65% (1303.1 to 850.1 mAh g–1) after 300 cycles. In comparison, the control Si-C anode retained only ≈8.3% (1207.9 to 100.1 mAh g–1) after 200 cycles. The strategy represents a pioneering method to construct high-performance and high-mass-loading Si-based electrodes for high-energy-density Li-ion batteries.