Uranyl Peroxide Nanocage Assemblies for Solid-State Electrolytes

Hybrid nanocomposites of uranyl peroxide nanocages are assembled from the ionic interaction between anionic uranyl peroxide nanocage clusters (Li44K16[UO2(O2)(OH)]60, U60) and cationic surfactants. As a porous nanocapsule, one U60 cluster can uptake as much as ∼ 44 Li+ ions, serving as the Li+ storage and transportation center. The nanocomposites show enriched microphase-separated structures ranging from lamellar to hexagonal columnar structures depending on the geometries of introduced surfactants. The U60 enriched phases serve as nanochannels for Li+ ion transportation. The Li+ conductivity of the nanocomposites exhibits a crossover at 295 K from the Vogel–Fulcher–Tammann temperature dependence law to Arrhenius law, suggesting different Li+ conducting mechanisms across the critical temperature (Tc) phase-transition temperature of the hybrid materials. The Li+ ions diffuse through dynamic segmental motion of the nanocomposites above Tc and through a typical hopping mechanism below Tc. The design of the nanocomposites offers approaches to decouple the ionic transportation and dynamics of surfactant chains and therefore paves a way to fabricate solid-state electrolytes with both high ion conductivities and promising mechanical strengths.