A Stable Conversion and Alloying Anode for Potassium-Ion Batteries: A Combined Strategy of Encapsulation and Confinement

Potassium-ion batteries based on conversion/alloying reactions have high potential applications in new-generation large-scale energy storage. However, their applications are hindered by inherent large-volume variations and sluggish kinetics of the conversion/alloying-type electrode materials during the repeated insertion and extraction of bulky K⁺ ions. Although some efforts have been focused on this issue, the reported potassium-ion batteries still suffer from poor cycling lifespans. Here, a superior stable antimony selenide (Sb₂Se₃) anode is reported for high-performance potassium-ion batteries through a combined strategy of conductive encapsulation and 2D confinement. The Sb₂Se₃ nanorods are uniformly coated with a conductive N-doped carbon layer and then confined between graphene nanosheets. The synergistic effects between conductive coating and confinement effectively buffer the large volumetric variation of the conversion/alloying anodes, which can maintain structural stability for superior cyclability. The as-prepared anodes exhibit a high reversible specific capacity of ≈590 mA h g⁻¹ and outstanding cycling stability over 350 cycles. In situ and ex situ characterizations reveal a high structural integration of the large-volume-change Sb₂Se₃ anodes during a reversible K storage mechanism of two-step conversion and multistep alloying processes. This work can open up a new possibility for the design of stable conversion/alloying-based anodes for high-performance potassium-ion batteries.