Balancing interfacial adhesion, stress accommodation, and Li+ transport via ether-containing copolymer binders for high-performance SiOx anodes

Silicon suboxide (SiO x ) anodes offer high specific capacity but suffer from severe volume changes that disrupt electrode integrity and ion transport during cycling. Herein, ether-containing poly(acrylamide- co -acrylic acid- co -diethylene glycol monoethyl ether acrylate) (PAAM-DEGA) binders were developed to simultaneously enhance interfacial adhesion, stress accommodation, and Li + transport. Flexible ethylene glycol units enhanced segmental mobility, electrolyte affinity, and ionic conductivity, whereas, higher DEGA incorporation was associated with stronger interchain interactions and polymer aggregation. Consequently, among the compositions investigated, PAAM-DEGA3 (with moderate DEGA content) provided the most favorable balance among interfacial adhesion, stress accommodation, and Li + transport. The resulting SiO x electrode exhibited an initial Coulombic efficiency of 83.9% and retained 87.8% of its capacity after 50 cycles at 1.0C. Even at a SiO x loading of 2.0 mg cm −2 , it retained 80.3% after 50 cycles and delivered 1153.0 mAh g −1 at 3.0C. Electrochemical and post-cycling analyses confirmed enhanced Li + diffusion, reduced charge-transfer resistance, suppressed electrode deformation and delamination, and improved interfacial stability. Moreover, a LiFePO 4 //SiO x full cell employing PAAM-DEGA3 maintained stable cycling up to 100 cycles at 1.0C. These results establish controlled ether incorporation as an effective strategy for balancing binder properties toward high-performance SiO x anodes.