Dual-clay composite electrolyte with rigid-flexible interlocked architecture for safe lithium metal batteries

A mineral-dominant dual-clay solid electrolyte was developed. • Dual-clay functional division enables a rigid-flexible electrolyte architecture. • Confined DMSO and the negatively charged Mnt interlayers induce a weak-solvation-like Li + transport state. • The electrolyte delivers improved safety, interfacial kinetics, and cycling stability. Developing solid electrolytes that combine high ionic conductivity, robust mechanical stability, and fast interfacial kinetics is critical for safe lithium metal batteries, yet these requirements are rarely met simultaneously in conventional polymer- or inorganic-dominant systems. Herein, we report a mineral-dominant dual-clay composite solid electrolyte (DCCSE, >50 wt% mineral content), in which montmorillonite serves as the continuous ion-transport phase, attapulgite acts as the rigid reinforcing framework, and their functional division enables a rigid-flexible integrated electrolyte architecture. Through a one-step organic-inorganic synergistic modification strategy, Na + /Li + exchange in montmorillonite is coupled with the replacement of native interlayer water by dimethyl sulfoxide, thereby constructing a Lithium bis (trifluoromethanesulfonyl)-imide−dimethyl sulfoxide modified montmorillonite transport channel. Structural characterization and molecular dynamics simulations reveal that the negatively charged interlayer environment of montmorillonite, together with interlayer DMSO, enlarges the interlayer spacing, lowers the Li + migration barrier, and induces a weak-solvation-like transport state by suppressing TFSI − participation and reconstructing the local coordination of Li + . As a result, DCCSE delivers an ionic conductivity of 2.1 × 10 −4  S cm −1 , an activation energy of 0.48 eV, a Li + transference number of 0.64, and an electrochemical stability window of 4.5 V at 60 °C, together with significantly enhanced mechanical strength, thermal stability, and flame retardancy. Li|Li symmetric cells stably cycle for over 1700 h at 0.1 mA cm −2 , while LFP|DCCSE|Li full cells retain 94.1% of their capacity after 500 cycles at 0.5C. This work proposes a new design concept for solid electrolytes based on the synergistic functional division of dual clays and confined-solvation regulation within minerals, providing a new design paradigm for constructing low-cost, highly safe, and mechanistically tunable solid-state lithium metal battery electrolytes from natural minerals. Download: Download high-res image (279KB) Download: Download full-size image