PolySchiff based self-healing solid-state electrolytes for lithium ion battery

Abstract

Vitrimers are novel polymeric materials consisting of dynamic covalent networks that can change their topology in response to external stimuli. Here, we reported flexible solid polymer electrolyte (SPE) with room temperature self-healing properties based on imine dynamic network. The effect of cross-linking degree, the content of succinonitrile (SN) plasticizer and lithium salt on the lithium ion conductivity (σ) was carefully studied. With the addition of the lithium salt, the Tg of pure polyschiff film is apparently enhanced and the vitrimers electrolyte with lower cross-linking degree show a lower Tg. The σ shows an obviously increasing trend with the dropping cross-linking degree and higher SN content, and it reach a maximum value of 6.43 × 10−4 S/cm at 30 wt % LiTFSI at 60 °C. Importantly, the cutted vitrimers electrolyte show 74 % recovery of its original tensile strength after self-healing at room temperature. Furthermore, the electrochemical window was widened with SN addition, up to 5.1 V vs. Li/Li+. The fabricated Li||PSFSPE@0.5SN||LiFePO4 cell also demonstrates a 100mAh/g discharge capacity at 0.05C after 50th cycles, showing its possible application of imine-based polymer electrolyte. Importantly, the SPEs membranes with imine bonds can heal damages outside or inside a battery without deterioration of discharging capacity of lithium ion battery.