High electrochemical performance poly(ethylene oxide)/2,4-toluene diisocyante/polyethylene glycol as electrolytes for all-solid-state lithium batteries

Polymer electrolytes are considered as the most commercially valuable solid electrolytes due to their flexibility and electrochemical stability. In this work, we prepared solid polymer electrolytes (SPEs) based on poly(ethylene oxide) (PEO) and a liner amorphous copolymer 2,4 -toluene diisocyante/polyethylene glycol (TDI/PEG). The optimal electrolyte PEO/TDI/PEG(PTP) with 20% TDI-PEG content presents a maximum conductivity of 0.17 mS cm^-1 at 60 °C in addition to a superior wide electrochemical window (reaches 5 V). Simultaneously, this SPEs also show excellent thermal stability up to 300 °C. Meanwhile, 3D-graphene foam was synthesized to modified LiFePO₄ as cathode material with improved electrochemical performance. The assembled solid-state GLFP/PTP20%/Li battery exhibits an initial reversible discharge specific capacity of 141.3 mAh·g^-1 and robust galvanostatic cycle performance with negligible capacity loss over 100 cycles. Therefore, the PEO-TDI-PEG films are highly promising polymer electrolytes for high performance all-solid-state lithium batteries.