Non-isocyanate poly(hydroxyurethane)-based networks as solid polymer electrolytes for lithium metal batteries

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.