Stress-relieving and interface-adaptive self-healing binder for enhanced durability of Si/graphite anodes

Silicon/graphite (Si/G) composite anodes provide a practical route to increasing the energy density of lithium-ion batteries. However, their durability is often limited by interfacial debonding and crack formation caused by severe Si volume changes and the mismatched surface chemistries of Si and graphite. Herein, an interface-adaptive, intrinsically self-healing carboxylated poly(ether-urethane) (ISCP) binder is developed for Si/G electrodes. It features a soft–hard segmented architecture enriched with multiple hydrogen bonding interactions and dynamic disulfide bonds. This segmented structure also imparts intrinsic amphiphilicity by combining polar carboxyl-rich domains with less-polar polyether regions, thereby enhancing interfacial compatibility. Consequently, the optimized ISCP-based Si/G composite electrode delivers a high initial Coulombic efficiency of ∼88% and excellent cycling stability, with capacity retentions of 96.3% and 85.4% after 300 and 500 cycles, respectively, at 0.5C. At a higher mass loading of 5.32 mg cm −2 , the electrode further delivers an initial areal capacity of 3.65 mAh cm −2 , highlighting its relevance under practical loading conditions. These findings demonstrate that integrating interfacial adaptability, intrinsic self-repair, and Li + -conducting functionality within a single thermoplastic binder is an effective strategy for suppressing mechanically driven failure and enabling durable, high-capacity Si/G anodes. • ISCP binder integrates adhesion, stress relaxation, Li + transport, and self-healing. • Soft–hard amphiphilic segments improve compatibility across Si/graphite interfaces. • Initial Coulombic efficiency (ICE) reaches 88% with stabilized SEI formation. • ISCP-55@Si/G retains 85.4% capacity after 500 cycles at 0.5C (2.5 mg cm −2 loading). • High-loading Si/G electrodes deliver 3.65 mAh cm −2 at 5.32 mg cm −2 mass loading.