Ultrathin Aramid/COF Heterolayered Membrane for Solid-State Li-Metal Batteries

Ultrathin, ultrastrong, and highly conductive solid-state polymer-based composite electrolytes have long been exploited for the next-generation lithium-based batteries. In particular, the lightweight membranes that are less than tens of microns are strongly desired, aiming to maximize the energy densities of solidstate batteries. However, building such ideal membranes are challenging when using traditional materials and fabrication technologies. Here we reported a 7.1 mu m thick heterolayered Kevlar/covalent organic framework (COF) composite membrane fabricated via a bottom-up spin layer-by-layer assembly technology that allows for precise control over the structure and thickness of the obtained membrane. Much stronger chemical/mechanical interactions between cross-linked Kevlar and conductive 2D-COF building blocks were designed, resulting in a highly strong and Li+ conductive (1.62 x 10(-4) S cm(-1) at 30 degrees C and 4.6 x 10(-4) S cm(-1) at 70 degrees C) electrolyte membrane that can prevent solid-state batteries from short-circuiting after over 500 h of cycling. All-solid- state lithium batteries using this membrane enable a significantly improved energy density.