Zero‐Strain Structure for Efficient Potassium Storage: Nitrogen‐Enriched Carbon Dual‐Confinement CoP Composite

Abstract A new type of anode material in which small‐sized CoP nanoparticles coated with N‐doped carbon are immobilized into 1D nitrogen‐doped carbon frameworks (CoP@NC⊂NCFs) is accurately synthesized via self‐template catalysis. The hierarchical structure bears various structural advantages, including more active sites and ultrahigh electrical conductivity provided by enriched nitrogen, strong interface interaction between CoP and N‐doped carbon, and the stability of the structure. As a result, the rapid potassium ion reaction kinetics and the strong adsorption of potassium ions of CoP are realized, verified by galvanostatic intermittent titration and density function theory calculations. In addition, through the advanced in situ characterization techniques, the solid‐solution reaction mechanism of CoP and potassium ions is clarified. The zero‐strain structure of CoP further ensures structural robustness, giving CoP@NC⊂NCFs excellent potassium storage properties, especially cycle stability with a capacity of ≈206 mAh g⁻¹ at 0.1 A g⁻¹ for 1200 cycles, achieving an ultralow decay rate of 0.01%. The corresponding K‐ion full cell is also prepared, as expected, and shows stable capacity retention.