Solid polymer electrolytes based on polysiloxane with anion-trapping boron moieties for all-solid-state lithium metal batteries

Cross-linked solid polymer electrolytes (SPEs) based on ion-conducting poly(ethylene glycol) (PEG), flexible polysiloxane, and anion-trapping boron cross-linker (BPC) were prepared via thiol-ene click reaction for lithium metal batteries. Various thermal and electrochemical properties of SPEs were systematically investigated by varying the content of BPC. Thermally stable free-standing SPE systems could be obtained due to the cross-linked structure, while relatively high ionic conductivity of about 1.3 × 10 −4 S cm −1 at 60 °C was obtained at the same time by the flexible polysiloxane moiety. The boron moiety in BPC could increase the lithium ion transference number compared to the corresponding boron-free SPE due to the anion-trapping capability of boron atom. The formation and growth of lithium dendrites were effectively suppressed by the anion-trapping capability and mechanically stable cross-linked structure of the SPE. • Novel solid electrolytes (CSPE-Bs) based on polysiloxane and boron cross-linker is reported. • CSPE-Bs are thermally and electrochemically stable. • CSPE-B60 shows ionic conductivity of 1.3 × 10 −4 S cm −1 at 60 °C. • CSPE-B60 shows lithium ion transference number of 0.35. • Excellent cycle stability is achieved in V 2 O 5 /Li cells.