Planar supercapacitor devices with nanometer electrodes

The pursuit of on-chip high-performance energy storage devices has been greatly stimulated by the rapid development of miniaturized electronic devices. We fabricated a planar supercapacitor that utilizes stacked two-dimensional exfoliated layers of graphene and molybdenum disulphide (MoS₂) as electrodes of nanometer thickness (∼6 nm). The MoS₂/graphene supercapacitor achieves a profound areal capacitance of 678 mF cm^-2 at 1 mV s^-1, which is 2726% higher than those of MoS₂ exfoliated layer based electrodes (24 mF cm^-2). The conducting interface of graphene enhances the formation of an electric double layer across both the basal plane and edges of MoS₂via diffusion between the interlayers. Moreover, in situ biasing of one of the MoS₂ electrodes induces a drastic enhancement of 539% in the electrochemical capacitance at 5 mV s^-1 and evidences diffusion dominant charging dynamics. Thus, a planar supercapacitor paves the way to control the charge dynamics for energy storage.