Transition Metal Atom–Cluster Synergistic Modification with Tuned d‐band Center Imparts Longevous Potassium Metal Anodes

The tailored nucleation and growth of potassium metal over a current collector is essential to realize longevous potassium metal anodes. The commercial current collector lacks sufficient nucleation sites and fails to guide uniform deposition, underscoring the request for interfacial modulation maneuvers. Herein, we develop transition metal atom-cluster moiety decorated N-doped hollow carbon nanosphere to modify the Al current collector. In a Fe model system, the Fe single atoms provide high surface energy and fast charge transfer, while Fe clusters serve as local electron reservoirs. This cooperative architecture manages to tune the d-band center, accordingly promoting the potassium capture and minimizing the nucleation overpotential to merely 4 mV. Theoretical simulations and in situ microscopic/spectroscopic characterizations evidence that the synergistic modification markedly accelerates potassium plating/stripping kinetics, enabling prolonged symmetric-cell cycling (approaching 3000 h) and stabilized full-cell performance (0.022% decay rate per cycle over 2000 cycles). This strategy could be extended to other transition metals (e.g., Co, Ni, or Cu), offering a paradigm for atomic-level interfacial engineering toward reversible alkali metal batteries.