High-performance ionic liquid-based nanocomposite polymer electrolytes with anisotropic ionic conductivity prepared by coupling liquid crystal self-templating with unidirectional freezing

Abstract

We report a facile and versatile assembly technique that combines a unidirectional freezing method, a liquid crystal self-templating approach and a vacuum degassing method to prepare high-performance ionic liquid (ILs)-based nanocomposite polymer electrolytes (NCPE) with highly ordered honeycomb-like microporous poly(vinyl alcohol) (PVA) scaffolds containing self-organized halloysite nanotubes (HNTs). Regarding its conductivity property, the ILs-based NCPE exhibits significant anisotropy, and its ionic conductivity can reach 5.2 × 10⁻³ S cm⁻¹ at 30 °C in the direction parallel to the freezing, which is more than 500 times higher than that obtained the direction perpendicular to the freezing, which is 9.6 × 10⁻⁶ S cm⁻¹ at 30 °C. More importantly, as a consequence of the compact self-assembly of HNTs into structured composites, the obtained ILs-based NCPE, which presents extremely thin channel walls (60–100 nm), can exhibit a combination of very high compression modulus of 46.5 MPa and high temperature robustness, whereas the dynamic modulus can reach 10⁷ Pa at 200 °C. This material design has great potential for the development of high-performance polymer electrolytes.