Flexible Solid Electrolytes from Two-Dimensional Metal Carbide, Polymer, and Ionic Covalent Organic Frameworks

As the demand for mobile electronic devices continues to grow, the development of all-solid-state lithium metal batteries has emerged as a promising solution to reduce the safety risks associated with conventional lithium-ion batteries. Herein, we introduce an approach to preparing a composite solid-state electrolyte by integrating two-dimensional (2D) MXenes with cationic covalent organic frameworks (cCOFs). These frameworks are based on ethidium bromide (EB-cCOF) and porphyrin (POR-cCOF), and are incorporated into the poly(ethylene oxide) (PEO)-based solid electrolytes. The synthesized MXenes and cCOFs serve as multifunctional additives, reducing the PEO crystallinity and enhancing segmental motion. We observed a synergistic effect when COFs and MXene were used in preparing electrolytes, highlighted in the observed increase in the ionic conductivity at room temperature. Additionally, the electrolyte exhibits improved thermal stability up to ≈380 °C and retains ≈9% more residual mass at 1000 °C. These results highlight the potential of hybrid solid electrolytes as promising candidates for advancing high-performance solid-state batteries.