Rb intercalation enhanced the supercapacitive performance of layer-structured MoS2 as a 2D model material

Abstract

Intercalation of alkali metals has proved to be an effective approach for the enhancement of the energy storage performance in layered-2D MoS₂. However, the research so far has been limited to the Li and Na ion intercalation with K ions being recently investigated. Herein, we demonstrate, for the first time, the extraordinary capacitance performance of Rb-ion intercalation in the inter-layer of the 1T, 2H, and 3R MoS₂ polymorphs. This work elucidates the capacitance performance in terms of quantum capacitance and intercalation strength. Rb-Intercalation into MoS₂ layers stabilizes the 1T phase more than Li ions and imparts metallic behavior to the semiconducting 2H and 3R phases. Concurrently, the quantum capacitance of the three phases dramatically increases, surpassing that of graphene and doped graphene. The calculated quantum capacitance can reach as high as 2700, 3250, and 3300 F g⁻¹ for the 1T, 2H, and 3R phases, respectively, rendering the Rb ion a superior choice for boosting the energy storage performance of the MoS₂-based supercapacitor electrodes.