Constructing Highly Conductive and Thermomechanical Stable Quasi-Solid Electrolytes by Self-Polymerization of Liquid Electrolytes within Porous Polyimide Nanofiber Films

摘要

Solid electrolytes are being considered as an effective solution to replace liquidones for building safer batteries, but they suffer either low ionic conductivityor large contact ohmic impedance. Here, a highly conductive and thermomechanicallystable quasi-solid electrolytes (QSE) by self-polymerization of acommercially available liquid electrolytes (1,3-dioxolane (DOL), 1,2-dimethoxyethane(DME), lithium trifluoromethane sulfonimide (LiTFSI) and LiPF_6) atroom temperature in a porous polyimide nanofiber film are reported. LiPF_6initiates the ring-opening reaction of DOL and LiTFSI promotes the selfpolymerizationto form poly-DOL (PDOL), while the plasticizer of DME solidifiesthe PDOL. On the other hand, polyimide has a great affinity with PDOL thatfacilitates to form stable QSE network. As a result, the QSE film shows a highroom-temperature ionic conductivity of 2.9 × 10~(?3) S cm~(?1), a high mechanicalstrength of 31 MPa, and high heat resistance to 160 ℃. The LiFePO_4‖QSE‖Libatteries with a high cathode loading of ≈18.7 mg cm~(?2) show great cyclingperformance and stable electrode/electrolyte interfaces at a high current rate of0.5 C with a capacity retention of 91.8 over 200 cycles at room temperature.