Architecting a Robust Yarn-Like CNT Framework for Structurally Resilient ZnSe Anodes in Potassium–Ion Batteries

초록

The development of structurally stable anodes with high capacities and long cycle lives is essential for the development of potassium–ion batteries. Conversion-type anodes have attracted considerable attention in potassium–ion batteries (PIBs) due to their high theoretical capacities. However, their practical application is hindered by severe volume variation, sluggish reaction kinetics, and structural degradation during repeated potassiation and depotassiation. Herein, we report a novel yarn-like microsphere (Y-CNT/ZnSe@NC) architecture that integrates a nanoconfined active material with a conductive flexible framework. This structure was fabricated through a scalable spray-drying process followed by carbonization and selenization, enabling the uniform encapsulation of N-doped carbon-coated ZnSe nanoparticles within a three-dimensional network of carbon nanotubes (CNTs). The resulting microspheres exhibited a compact yet porous architecture that enhanced ion transport and provided a continuous electron-conductive network. The conformal CNT framework effectively mitigated the volume changes of ZnSe during cycling, suppressed nanocrystal overgrowth during heat treatment, and maintained structural integrity. Consequently, the Y-CNT/ZnSe@NC anode exhibited superior electrochemical performance, delivering a reversible capacity of 220 mA h g−1 with a Coulombic efficiency of ∼99% over 2000 cycles and excellent rate capability. In contrast, CNT-free electrodes suffer from capacity fading owing to structural degradation. In-depth analyses further confirmed the mechanical robustness and stable charge-transfer characteristics of the CNT-embedded structure. This study highlights the advantages of uniformly encapsulating active materials within a CNT network and provides a versatile platform for designing next-generation high-energy-density long-life anodes based on transition-metal chalcogenides.

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