Polar molecule-derived segmental motion in polymer solid electrolyte and integrated electrode architecture enable stable silicon anodes

Solid-state lithium-ion batteries (SSLBs) employing Si-based anode are promising high energy–density storage devices owing to enhanced safety and electrochemical stability. Nevertheless, developing solid-state electrolytes featuring easiness of forming intimate interface with electrode, high ionic conductivity, and good mechanical compatibility with Si/C still remains challenging. Herein, we report a poly(vinylene carbonate)/LiTFSI/succinonitrile (PVC/Li/SN) polymer electrolyte and construct a highly integrated Si/C-electrolyte architecture with stable interfacial affinity. Benefitting from unique polar molecule-derived segmental motion, the PVC/Li/SN electrolyte exhibits both high ionic conductivity (5.1 × 10⁻⁴ S cm⁻¹) and good mechanical compatibility, as well as wide electrochemical window, high thermal stability, and fire resistance. Moreover, the integrated architecture with infiltrated polymer electrolyte ensures sufficient and intimate interface contact with Si/C anode during the whole charging/discharging processes. In addition, the generated solid electrolyte interphase (SEI) layer consisting of multiple inorganic components and PVC chains further improves the interfacial stability and ionic conductivity. As a result, the integrated solid half-cell manifests excellent cyclic stability and rate capability, superior to the liquid electrolyte counterpart. We also assemble the integrated Li||PVC/Li/SN-30||LiFePO₄ and Li||PVC/Li/SN-30||LiNi_0.8Co_0.1Mn_0.1O₂ solid half-cells, both of which exhibit high capacity retention after 100 cycles. Moreover, the Si/C||PVC/Li/SN-30||LiFePO₄ full cell exhibits excellent cycling stability over repeated cycles. This work provides new design guideline of solid-state polymer electrolytes for matching high-capacity Si-based anode.