Towards Cs-ion supercapacitors: Cs intercalation in polymorph MoS2 as a model 2D electrode material

Abstract

Intercalation of alkali metals has proved to be an effective approach for the enhancement of the energy storage performance in layered-2D materials. However, the research so far has been limited to Li and Na ion intercalation with K ions being recently investigated. Although cesium (Cs) salts are highly soluble in water, Cs⁺ intercalation has been addressed neither in batteries nor in supercapacitors so far. Herein, we demonstrate the exceptional effect of Cs⁺ intercalation in MoS₂ as a model 2D material to boost its performance as a potential supercapacitor electrode. Cs⁺ intercalation was found to stabilize the metastable 1T phase and increase the conductivity of the 2H and 3R phases. Cs⁺-Intercalated 1T MoS₂ showed higher quantum capacitance (C_Q) than doped graphene.