Flexible Nanocomposite Polymer Electrolyte Based on UV-Cured Polyurethane Acrylate for Lithium Metal Batteries

The inherent safety issues of commercial organic liquid electrolytes make it hard to deploy them in lithium metal batteries. By contrast, nanocomposite polymer electrolytes (NCPEs) can not only suppress the growth of lithium dendrites but also have the functions of separators to substitute the liquid electrolytes. In this work, a kind of NCPE was designed by in situ hydrolysis of tetrabutyl titanate to form in situ TiO2 nanoparticles throughout the UV curing cross-linked polyurethane acrylate network, and the addition of an ionic liquid as a plasticizer further enhanced the safety property of the NCPE due to its intrinsic excellent thermal stability. The optimized NCPE-4 sample shows a high ionic conductivity of 1.1 × 10–3 S cm–1 at 30 °C, a sufficiently stable interface compatibility between the NCPE and electrode, and a higher electrochemical stability window of 4.8 V (vs Li/Li+). More interestingly, the assembled LiFePO4/NCPE-4/Li coin cell attains a discharge capacity of 149.1 mA h g–1 after 200 cycles at 0.5 C, and even at the high rate of 3 C, the capacity still stays over 83 mA h g–1. These results demonstrate that the novel NCPE-4 could be a promising candidate for the practical applications in lithium metal batteries.