WSe 2 /MoSe 2 with a better‐matched heterointerface dominating high‐performance potassium/sodium storage

Abstract Constructing a valid heterointerface with a built‐in electric field is an effective strategy for designing energy storage anodes with exceptional efficiency for potassium‐ion batteries (PIBs) and sodium‐ion batteries (SIBs). In this study, WSe 2 /MoSe 2 nanosheets with a better‐matched and stable heterojunction interface were uniformly embedded in carbon nanofiber frameworks (WSe 2 /MoSe 2 /CNFs). The ion/electron transfer kinetics were facilitated by heterointerfaces with an enlarged effective utilization range. Meanwhile, the heterointerface directed electron transfer from MoSe 2 to WSe 2 and had significant potassium adsorption capability. The ultra‐high pseudocapacitance contribution originating from the heterostructure and morphological features of the WSe 2 /MoSe 2 nanosheets contributed to enhancing high‐rate energy storage. Moreover, in situ X‐ray diffraction and ex situ X‐ray photoelectron spectroscopy revealed the potassification/depotassification behavior of the WSe 2 /MoSe 2 /CNFs during the conversion reaction. Consequently, after 500 cycles at 5 A·g −1 , the WSe 2 /MoSe 2 /CNF anode demonstrated an outstanding long‐term cycling performance of 125.6 mAh·g −1 for PIBs. While serving as a SIB electrode, it exhibited an exceptional rate capability of 243.5 mAh·g −1 at 20 A·g −1 . With the goal of developing high‐performance PIB/SIB electrode materials, the proposed strategy, based on heterointerface adaptation engineering, is promising.