Binder-induced inorganic-rich solid electrolyte interphase and physicochemical dual cross-linked network for high-performance SiOx anode

Abstract

Silicon oxide (SiO_x) is heralded as the forefront anode material for high-energy density lithium-ion batteries, owing to its exceptional specific capacity. Nevertheless, the traditional combination of polyacrylic acid binder and acetylene black conductive carbon continues to struggle with the immense stress induced by the repetitive volume expansion and contraction processes. Here we report a high ionic conductivity, sulfonyl fluoro-containing binder for SiO_x anode via free radical copolymerization reaction between perfluoro (4-methyl-3,6-dioxaoct-7-ene) sulfonyl fluoride and acrylic acid. The electrode fabrication process incorporated amino-functionalized carbon nanotubes (CNT-NH₂) as the conductive agent. A three-dimensional conductive network structure is constructed through physical and chemical double cross-linking interactions between the -COOH and -SO₂F functional groups of PAF_0.1 binder, the -NH₂ groups of CNT-NH₂, and the -OH groups on the surface of SiO_x, including hydrogen bonds and covalent bonds. In addition, the binder induces the formation of a solid electrolyte interphase (SEI) rich in inorganic components such as Li₂O, Li₂SO₃, Li₂CO₃, and LiF. Benefiting from the synergistic effects of the physically and chemically double cross-linked three-dimensional conductive network constructed by the PAF_0.1 binder and CNT-NH₂, coupled with the rich-inorganic SEI, the SiO_x anode delivers exceptional rate performance, cycle stability, and lithium-ion diffusion dynamics.