Non‐Isocyanate Poly(hydroxyurethane)‐Based Networks as Solid Polymer Electrolytes for Lithium Metal Batteries

Abstract We report here on the facile synthesis of poly(hydroxyurethane) (PHU) networks obtained via the ring‐opening of cyclic carbonates present on bio‐based carbonated soybean oil by poly(ethylene glycol) (PEG) segments of various lengths and functionalized at both ends by amines. We also explore the possibility to prepare PHU‐poly(epoxy) mixed networks by additionally incorporating PEG segments functionalized at both ends by epoxides in the reaction mixture. The accordingly obtained polymer networks possess high flexibility and a good interfacial stability. After salt loading, the solid polymer electrolyte (SPE) membranes based on PHU and PHU‐poly(epoxy) mixed networks exhibit ionic conductivities in the range of ~10 −4.5 to 10 −5 S cm −1 at 60 °C with oxidation stability >4.2 V versus Li/Li + . Further, their long‐term compatibility with lithium metal has been investigated for more than a hundred cycles in stripping and plating experiments. Those results drive the PHU‐based networks toward the development of electrolytes with a high degree of control on structure and properties, dealing with the trade‐off of mechanical and electrochemical properties usually met with PEG‐based SPEs.