Solid–Liquid Metal Single-Atom Clusters for Ultrafast Kinetics in Fast-Charging Na-Ion Batteries

Na⁺ desolvation and diffusion rates are determining steps that restrict fast charging in sodium-ion batteries (SIBs). Although desolvation and diffusion rates can be improved by the optimization of the solid electrolyte interphase (SEI), no existing architecture has achieved simultaneous rapid ion transport across the bulk phase, interphase, and solvent phase while maintaining 100% initial Coulombic efficiency (ICE). Specifically, we report an atomic-level strategy derived from recyclable materials that uniformly coordinates diverse single-atom alloying reactions to enable the assembly of solid-liquid single-atom channels for rapid ion transport across multiphase systems. Single-atom channels interconnect components through intelligent self-regulation, achieving ∼100% ICE in liquid-derived SEI while minimizing the Na⁺ desolvation and diffusion barrier. Ah-level engineering application cells show 200.62 Wh kg^-1 at 5 C, as well as 92.9% capacity retention for over 500 cycles at 7 C. The cells show 8 min charging time for 100% capacity at 10 C. Solid-liquid metal single-atom clusters open the door for fast-charging SIBs at the atomic level.