Cyclophosphazene-based hybrid polymer electrolytes obtained via epoxy amine reaction for high-performance all-solid-state lithium-ion batteries

A polymer electrolyte (PE) is considered as a kind of promising candidate in lithium batteries due to its high energy density and no leakage issue compared to the liquid electrolyte. However, poly(ethylene oxide) (PEO)-based electrolytes also have some problems such as inferior mechanical strength, low ionic conductivity, poor thermal stability, and flammability. These flaws often trigger a short circuit due to the growth of lithium dendrites, restrict the potential applications of lithium-ion batteries, and cause severe safety problems. Herein, we proposed a strategy to overcome these defects. Hexa(4-aminophenoxy) cyclotriphosphazene (HAmCP) was utilized as the core, and polyethylene glycol diglycidyl ether (PEGDE) was employed as the cross-linking agent Via a facile amino-epoxy reaction. The structure and purity of the substrate were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (H-1, C-13, and P-31 NMR) characterizations. The formed network polymer electrolyte was mechanically robust and flexible owing to the hybrid cyclophosphazene core and the cross-linked structure. The PE was thermally stable under the temperature of 368 degrees C with 5% decomposition of the polymer matrix and could be stretched up to 127% elongation without break. Meanwhile, the PE also exhibited fire-retardant ability to some extent compared with the pure PEO-based polymer matrix formed Via the radical polymerization of polyethylene glycol diacrylate (PEGDA). Furthermore, the all solid -state PE possessed ionic conductivity up to 10(-4) S cm(-1) at 30 degrees C and excellent interfacial stability with a lithium anode, thus contributing to stable cycling for high-performance batteries.