WSe₂/MoSe₂ with a better-matched heterointerface dominating high-performance potassium/sodium storage

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, WSe₂/MoSe₂ nanosheets with a better-matched and stable heterojunction interface were uniformly embedded in carbon nanofiber frameworks (WSe₂/MoSe₂/CNFs). The ion/electron transfer kinetics were facilitated by heterointerfaces with an enlarged effective utilization range. Meanwhile, the heterointerface directed electron transfer from MoSe₂ to WSe₂ and had significant potassium adsorption capability. The ultra-high pseudocapacitance contribution originating from the heterostructure and morphological features of the WSe₂/MoSe₂ 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 WSe₂/MoSe₂/CNFs during the conversion reaction. Consequently, after 500 cycles at 5 A·g⁻¹, the WSe₂/MoSe₂/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.