Cross-linked polymer electrolytes for highly performing lithium batteries working at ambient conditions

Ion-conducting, self-standing and tack-free poly(ethylene oxide)-based polymer electrolytes are successfully prepared via a rapid and easily up-scalable free radical polymerization, initiated by UV or thermal curing. This procedure is highly advantageous due to its easiness and rapidity in processing, high efficiency and eco-friendliness as the use of solvent is avoided. The crosslinking produced during curing allows the incorporation of a liquid solvent, RTIL or tetraglyme and LiTFSI salt, leading to a material with remarkable homogeneity and robustness. The cross-linked polymer network can efficiently hold plasticizers without leakage. Samples are thermally stable up to 375 °C under inert conditions. Excellent ionic conductivity (>0.1 mS cm–1 at 25 °C), wide electrochemical stability (> 5 V vs. Li), stable interfacial properties and dendrite nucleation/growth resistance are obtained. The lab-scale Li-polymer cells assembled with different electrode materials (e.g., LiFePO4, Li-rich NMC, LiCoPO4, TiO2) show stable charge/discharge characteristics with limited capacity fading upon very long-term reversible cycling, even at room temperature. The overall remarkable performance of the novel polymer electrolytes postulates the possibility of effective implementation in the next generation of safe and durable secondary Li-based polymer batteries working at ambient and/or sub-ambient temperatures.