Ultrathin Mesoporous Sandwiched Junctions with Monolayered Mesopores for Ultrahigh-Rate Sodium-Ion Storage

Rational nanostructural design for anode materials plays a crucial role in sodium-ion batteries (SIBs). Two-dimensional (2D) mesostructured composites capable of ideal diffusion kinetics and electronic conductivity are promising materials; however, difficulties remain in actual synthesis. Herein, we present a sequential monomicelle assembly strategy to synthesize uniform monolayered mesoporous TiO₂-reduced graphene oxide sandwiched junctions (meso-TiO₂/rGO sandwich), which enables superior pseudocapacitive sodium-ion storage. Such a sandwich structure has an ultrathin thickness, monolayered TiO₂ mesopores at both sides of the rGO, a high surface area, and a uniform mesopore size. The combination of ultrathin 2D morphology, excellent mesoporosity, and electrical conductivity gives rise to comprehensive electrolyte access, reduced Na⁺ diffusion lengths, and promoted charge transfer. Remarkably, the sandwich anode exhibits a high reversible capacity, great rate capability, and cycling stability. Our study exemplifies the significance of constructing hybrid materials as an effective strategy for fast electrochemical sodium-ion storage.