Water-Processable Covalent-and-Supramolecular Polymeric Binders for Silicon/Carbon Anodes with High Interfacial...

Silicon/carbon (Si/C) composite anodes are among the most promising candidates for high-energy-density lithium-ion batteries but suffer from severe volume fluctuation and interfacial degradation during cycling. Herein, we report a water-processable covalent-and-supramolecular polymeric binders (CSPBs) that synergistically dissipate mechanical stress and promote Li⁺ transport to stabilize the Si/C anode interface. The CSPBs integrate poly(acrylic acid) (PAA), amine-terminated eight-arm poly(ethylene glycol) (8arm-PEG-NH₂), and benzo-21-crown-7/secondary ammonium host-guest complexes through amidation during electrode fabrication. The covalent linkages impart strong structural integrity, while the reversible supramolecular interactions act as sacrificial bonds to dissipate stress arising from Si volume expansion. Additionally, oxygen-rich PEG chains form continuous Li⁺ conduction pathways, enabling efficient ion transport. As a result, the CSPB-2-based Si/C anode delivers a high specific capacity of 582.0 mAh g^-1 after 265 cycles at 1C, with superior rate capability than the electrodes based on PAA or solely covalently cross-linked binders (CCBs). Kinetic analysis reveals an enhanced Li⁺ diffusion coefficient, confirming the improved ionic conductivity of the binder system. This work demonstrates a new strategy for integrating covalent anchoring and dynamic supramolecular adaptability within a sustainable, water-processable polymeric binder system, paving the way for the design of durable and high-performance silicon-based anodes.