Bismuth Telluride Nanoplates Hierarchically Confined by Graphene and N‐Doped C as Conversion‐Alloying Anode Materials for Potassium‐Ion Batteries

Abstract Potassium‐ion batteries (PIBs) have broad application prospects in the field of electric energy storage systems because of its abundant K reserves, and similar “rocking chair” operating principle as lithium‐ion batteries (LIBs). Aiming to the large volume expansion and sluggish dynamic behavior of anode materials for storing large sized K‐ion, bismuth telluride (Bi 2 Te 3 ) nanoplates hierarchically encapsulated by reduced graphene oxide (rGO), and nitrogen‐doped carbon (NC) are constructed as anodes for PIBs. The resultant Bi 2 Te 3 @rGO@NC architecture features robust chemical bond of Bi─O─C, tightly physicochemical confinement effect, typical conductor property, and enhanced K‐ion adsorption ability, thereby producing superior electrochemical kinetics and outstanding morphological and structural stability. It is visually elucidated via high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) that conversion‐alloying dual‐mechanism plays a significant role in K‐ion storage, allowing 12 K‐ion transport per formular unit employing Bi as redox site. Thus, the high first reversible specific capacity of 322.70 mAh g −1 at 50 mA g −1 , great rate capability and cyclic stability can be achieved for Bi 2 Te 3 @rGO@NC. This work lays the foundation for an in‐depth understanding of conversion‐alloying mechanism in potassium‐ion storage.