Coherent Single-Atom Dipole–Dipole Coupling Mediates Holistic Regulation of K+ Migration for Superior Energy Storage and Dendrite-Free Metal Deposition

Abstract

Potassium-based batteries, including potassium-ion (PIBs) and potassium metal batteries (PMBs), are gaining attention as alternatives to lithium-ion batteries (LIBs). However, potassium's large ionic radius (1.38 Å) reduces charge density, weakens solvation, and increases energy barriers for K⁺ diffusion, leading to slower reaction kinetics, thicker solid electrolyte interphase (SEI) layers, and dendrite formation. To address these challenges, a novel single-atom Fe-N₄ dipole–dipole coupling (SA.Fe) is proposed. The unique Fe-N₄ coordination and highly conductive Ketjen black (KB) substrate establish a rapid horizontal electron transfer network, enhancing electrode interface reactions. Moreover, Fe-N-C coordination generates a short-range polar electric field, improving K⁺ affinity and diffusion. This coherent single-atom coupling effectively regulates K⁺ migration, significantly enhancing reaction kinetics and lowering diffusion barriers. The SA.Fe anode delivers high reversible capacities (446.3 mAh g⁻¹) and exceptional durability (10 000 cycles at 2.0 A g⁻¹) in PIBs, alongside remarkable stability (600 cycles at 0.5 mA cm⁻²) and fast potassium metal (K metal) deposition without dendrite formation in PMBs. This study highlights the potential of coherent single-atom dipole coupling for efficient K⁺ storage and dendrite-free batteries, offering a promising pathway for next-generation potassium-based energy systems.