Solid-state polymer electrolytes have become promising candidates for high-energy-density lithium metal batteries (LMBs). However, they suffer from low ionic conductivities at room temperature. In this work, two types of composite polymer electrolytes based on a double-network polymer, an ionic liquid (IL) of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyr14TFSI) or 1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl) imide (EmimTFSI), and bis(trifluoromethane)sulfonamide lithium salt (LiTFSI) were prepared by a facile one-pot method. The two types of CPEs possess good mechanical properties, excellent thermal stability, and high ionic conductivities greater than 10−4 S cm−1 at 20 °C with 26 wt% IL. The performance diversity of the CPEs was also carefully investigated through a series of electrochemical measurements. Although the CPEs containing EmimTFSI show higher ionic conductivities than those of CPEs with Pyr14TFSI, the latter ones have wider electrochemical stability windows and better resistance to the growth of lithium dendrites. Moreover, CPE with 34 wt% Pyr14TFSI leads to Li/LiFePO4 batteries with favorable rate capability and cycling stability and a columbic efficiency of 98.8% at 20 °C, which suggests that CPEs are promising for practical application in solid-state LMBs.

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Single-component moisture-cured polyurethane (SPU) possesses the merit of easy preparation and high curing efficiency but suffers from poor apparent properties, mechanical performance, and thermal stability. Herein, the authors employ isophorone diisocyanate (IPDI) and 2-isopropyl-3-hydroxyethyl-1, 3-oxazolidines (IHO) to synthesize oxazolidine (termed as IPDI-IHO) for the subsequent modification of SPU. The structure and composition of the synthesized SPU/IPDI-IHO composites are unraveled by 1 H and 13 C NMR and FTIR spectroscopies. Apart from the curing properties of SPU/IPDI-IHO, the apparent properties, mechanical performance, thermal stability, and self-healing ability are evaluated. SEM and AFM characterizations reveal that IPDI-IHO incorporation significantly decreased the number of bubbles and thus reduce the SPU-based sample surface roughness. The thermal stability of SPU is notably improved after IPDI-IHO modification. The tensile strength and elongation at break also increases from 830 to 3710 kPa and from 210% to 600%, respectively, due to IPDI-IHO inclusion, with the optimal mechanical properties achieved at the IPDI-IHO mass ratio of 8 wt%. Furthermore, the cracks intentionally cut for the SPU/IPDI-IHO sample can be self-healed at 60 °C. The ensemble of the performance enhancements suggests that the IPDI-IHO developed in this work opens up a new route to fabricate high-performance SPU and related polymeric materials.