The development of high-capacity and low-cost energy storage systems are a top priority in electric vehicles and smart grids. Room temperature potassium-ion batteries (PIBs), which have the advantages of high theoretical capacity, abundant earth reserves, and low potassium costs, have recently emerged as an appealing alternative to traditional lithium-ion batteries (LIBs). In particular, finding advanced anode materials with suitable operation potential and high capacity is of significance for next-generation PIBs. In this regard, Sb-based materials have recently gained popularity as promising anode materials for batteries in terms of their suitable working potential, high density, and theoretical capacity. Among them, Sb₂Te₃ has a much higher density (6.66 g/cm³) than other Sb-based materials such as Sb₂O₃, Sb₂S₃, and Sb₂Se₃. This suggests that Sb₂Te₃ can have a high theoretical capacity. In addition, Te exhibits a higher conductivity than S or Se. Accordingly, the Sb₂Te₃ is appealing as an ideal anode for PIBs. Unfortunately, the Sb₂Se₃ has poor cycling stability and rate performances, which is primarily owing to the large volume change during alloying and dealloying.

In this study, using a simple hydrothermal strategy, we synthesized a carbon-coated Sb₂Te₃ nanocomposite (Sb₂Te₃@C). In the novel design, the Sb₂Te₃@C nanocomposite is compactly encapsulated by a uniform carbon layer, which effectively relieves structural stress leading to preventing structural pulverization and stabilize the solid electrolyte interface layer. As expected with this optimal design, the Sb₂Te₃@C nanocomposite electrode performed nicely suitable for PIBs. In addition, the effect of the alloying/dealloying process on the crystal structure of Sb₂Te₃@C was investigated using in- situ/ex-situ XRD patterns recorded at various stages of discharge and charge to clarify the alloying mechanism. Furthermore, a full cell made up of a Sb₂Te₃@C anode and a potassium Prussian blue type cathode also exhibited successful operation.