Noncombustible 7 µm-thick solid polymer electrolyte for highly energy density solid state lithium batteries

Solid polymer electrolytes have attracted significant attention due to their outstanding properties. Determining how to further improve the energy density, ionic conductivity and safety of batteries is key to industrialization. Here, we prepared an ultra-thin, highly safe PEO/LiTFSI/3% NH4PF6 @PA6 polymer solid electrolyte. Compared with conventional electrolytes, this polymer electrolyte can be up to 7 µm thick, leading to lower cell impedance and higher energy density. The Li//PEO/LiTFSI/3% NH4PF6 @PA6//Li cell can cycle for more than 2000 h at 60 °C. Besides, PEO-based electrolytes with only 3 wt% addition of NH4PF6 exhibits high fire safety. The pouch cell assembled using this electrolyte does not short-circuit under bending and cutting and does not burn even in a thermal runaway test.