Rechargeable sodium-ion batteries (SIBs) have been considered as promising energy storage devices owing to the similar "rocking chair" working mechanism as lithium-ion batteries and abundant and low-cost sodium resource. However, the large ionic radius of the Na-ion (1.07 Å) brings a key scientific challenge, restricting the development of electrode materials for SIBs, and the infeasibility of graphite and silicon in reversible Na-ion storage further promotes the investigation of advanced anode materials. Currently, the key issues facing anode materials include sluggish electrochemical kinetics and a large volume expansion. Despite these challenges, substantial conceptual and experimental progress has been made in the past. Herein, we present a brief review of the recent development of intercalation, conversion, alloying, conversion-alloying, and organic anode materials for SIBs. Starting from the historical research progress of anode electrodes, the detailed Na-ion storage mechanism is analyzed. Various optimization strategies to improve the electrochemical properties of anodes are summarized, including phase state adjustment, defect introduction, molecular engineering, nanostructure design, composite construction, heterostructure synthesis, and heteroatom doping. Furthermore, the associated merits and drawbacks of each class of material are outlined, and the challenges and possible future directions for high-performance anode materials are discussed.

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 (Bi2Te3) nanoplates hierarchically encapsulated by reduced graphene oxide (rGO), and nitrogen‐doped carbon (NC) are constructed as anodes for PIBs. The resultant Bi2Te3@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 Bi2Te3@rGO@NC. This work lays the foundation for an in‐depth understanding of conversion‐alloying mechanism in potassium‐ion storage.

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