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The development of potassium‐ion batteries (KIBs) relies on the exploration of stable layer‐structured oxide cathode materials and a comprehensive understanding of ion storage and diffusion behaviors. A multiphase riveting‐structured O3/P2/P3‐Na0.9[Ni0.3Mn0.55Cu0.1Ti0.05]O2 (Tri‐NMCT) is employed as cathode material for KIBs. It demonstrates an initial discharge specific capacity of 108 mA g−1 at current density of 15 mA g−1 in the voltage range of 1.5–4 V. Excellent cyclic stability is exhibited as well with a high 83% capacity retention after 600 cycles at a higher current density of 300 mA g−1. Based on the in‐situ XRD, it reveals that the P2 phase offers a more stable triangular prism site compared to the O3 phase. This stability inhibits the undesired phase transition from P3 to O3 during discharge, thereby ensuring the long‐term cyclic performance. Furthermore, Density of state (DOS) calculations and migration barrier analyses indicate a preferential migration of K+ ions to the P2 phase due to the lower Fermi level. This observation elucidates the structural preservation of the P3 phase during K+ embedding. Overall, this work sheds light on Tri‐NMCT as a promising cathode material for advanced KIBs. [ABSTRACT FROM AUTHOR]

The potassium dual-ion batteries (DIBs) have been attracting a great attention in recent years due to their promising environmental benignancy, high energy density, and long lifespan. The active materials based on conversion reaction mechanism are favorable and widely expected to alleviate the dendrite formation, red phosphorous was thus employed and fabricated into a three-dimensional porous carbon matrix anchored by P– O –C chemical bonding using vaporization–condensation–conversion process. Meanwhile, the elements modified carbon can not only guarantee the electronic conductivity and ions diffusion, but also alleviate the red phosphorous volumetric expansion and detachment. When coupled with graphite, the K-DIBs demonstrate excellent electrochemical performance with a high 213 Wh kg−1 energy density and a promising stability up to 650 cycles. This explored material will provide highly relevant insights for next-generation advanced energy storage systems. • New explored red phosphorous structure for potassium dual-ion batteries. • Inducing P– O –C chemical bonding to anchor red phosphorous for electronic conductivity and structure stability. • Excellent energy density of 213 Wh kg−1 and superior lifespan up to 650 cycles. [ABSTRACT FROM AUTHOR]