An oriented design of a π-conjugated polymer framework for high-performance solid-state lithium batteries

Abstract

Solid polymer electrolytes (SPEs) are garnering significant interest for use in solid-state lithium metal batteries. However, a critical challenge in the rational design of electrolytes lies in ensuring interfacial compatibility, as well as navigating the trade-off between ionic conductivity and mechanical strength, which are essential for safety and cycling stability, particularly when utilizing high-energy-density electrodes. We report a π-conjugated polymer film, 4.1 μm thick, achieved through supramolecular oriented self-assembly, serving as a safe SPE host. Through π electron engineering with local delocalization, porous planar and rigid-rod molecular backbones were achieved, serving for ionic conduction and structural support, respectively. In addition to exhibiting a high ionic conductivity (7.7 × 10⁻⁴ S cm⁻¹ at 25 °C along the aligned ion pathway), the π-conjugated polymer membrane also demonstrates extraordinary tensile strength (525 MPa) and supports robust cycling of Li symmetric cells for over 2500 hours. The utilization of a π-conjugated polymer host paves the way for the mass production of SPEs, promising safer and high-performance solid-state batteries.