Exploring the desired anode materials to address the issues of poor structural stability tardy redox kinetics caused by large potassium ionic radius are fatal for the realization of large-scale applications of potassium-ion batteries. In this work, the feasibility to achieve promoted K⁺ storage by constructing the model of CoS₂ enfolded in carbon was verified by the density functional theory calculations. And the results predicted a faster electron/potassium ion transport kinetics than bare CoS₂ by increasing electron carrier density and narrowing diffusion barrier. Therefore, an interfacial engineering strategy was applied and implemented to synthesize the CoS₂ nanoparticles enveloped in the S-doped carbon (CoS₂/SC) under this inspiration. The as-prepared CoS₂/SC composite exhibited a prominent rate capability and long cycling lifespan, delivering the high capacity of 375 mA h g⁻¹ at 0.2 A g⁻¹ at the 100th cycle and 273 mA h g⁻¹ at 2 A g⁻¹ over 300 cycles. The in/ex situ characterizations unraveled the converse mechanism of CoS₂/SC in K⁺ storage, showing an eventually reversible phase transformation of ${\mathrm{K}}_{\mathrm{x}}{\mathrm{C}\mathrm{o}\mathrm{S}}_2\leftrightarrow \mathrm{C}\mathrm{o}$ within the electrochemical reactions.

As anode materials for high-performance sodium-ion batteries and potassium-ion batteries, bimetallic selenides have attracted great concern due to their relatively high electrical conductivity and electrochemical activity. However, the formidable challenge in the reaction process is the large volume change, leading to the structural collapse of material, and eventually the decline in electrochemical performance. Herein, a composite of hierarchical CoSe₂–MoSe₂ tubes anchored on reduced graphene oxide nanosheets (CoSe₂–MoSe₂/rGO) is designed by an in situ hydrothermal selenization treatment. Benefiting from the synergistic effects between CoSe₂ and MoSe₂, unique hierarchical structure, and effective reduced graphene oxide coating, the CoSe₂–MoSe₂/rGO exhibited improved reaction kinetics and structural stability, and thus good electrochemical properties. A combination mechanism of intercalation and conversion of CoSe₂–MoSe₂/rGO by forming Na_xCoSe₂ and Mo₁₅Se₁₉ as intermediate states is put forward on the basis of in situ and ex situ XRD analyses.