Gate Field Induced Extraordinary Energy Storage in MoS₂-Graphene-Based Ultramicro-Electrochemical Capacitor

Abstract

On-chip microscopic energy systems have revolutionized device design for miniaturized energy storage systems. Many atomically thin materials have provided a unique opportunity to develop highly efficient small-scale devices. We report an ultramicro-electrochemical capacitor with two-dimensional (2D) molybdenum disulphide (MoS 2 ) and graphenebased electrodes. Due to the tunable density of states, 2D MoS 2 provides electric field-induced doping and, combined with a graphene interface, leads to a high carrier mobility. The fabricated solid-state energy storage device is obtained using a gel electrolyte that provides an electrochemical capacitance of 1.8 mF/cm 2 . An extraordinary enhancement of ∼3000% in electrochemical capacitance (55 mF/cm 2 from 1.8 mF/cm 2 , measured from a cyclic voltammetry curve) is observed upon application of back-gate field of −25 V, which is more than the enhancement (18%) observed in a MoS 2 electrochemical capacitor (0.95 mF/cm 2 from 0.8 mF/cm 2 ) without graphene, whereas the galvanic charge−discharge measurements analysis shows ∼1677% enhancement under the application of −25 V back-gate voltage. Thus, the electric field-induced doping in 2D MoS 2 , in addition to a high charge carrier mobility due to the graphene, plays a crucial role in an extraordinary large energy storage in the ultramicro-electrochemical capacitor. We also evaluated the capacitance response using an AC signal superimposed with the DC bias to investigate the influence of polarization potential on the electrolyte. The study provides a benchmark development of an ultramicro-electrochemical capacitor for ultrahigh charge storage capability.

Triazine-Based Two-Dimensional Porous Covalent Organic Framework for Efficient Electrode Materials for Electrocatalytic Hydrogen Generation and Hybrid Supercapacitors

“…Conversely, supercapacitors offer ultrahigh power density and longer cycle life than metal-ion batteries. − They operate through non-Faradic processes, electrochemical double-layer capacitors (EDLC), and the Faradic processes through reversible redox reactions in pseudocapacitors . Hybrid supercapacitors, which combine the benefits of both processes, have emerged as a solution with higher energy and power density and improved cycle life. , Various electrode materials, such as graphene, activated carbon, metal oxides, metal chalcogenides, conducting polymers, and organic frameworks, have been extensively explored for supercapacitor applications. − However, designing nanostructured frameworks with high surface area, porosity, and incorporation of redox-active moieties is crucial for achieving high-performance hybrid supercapacitors.…”

Developments in conducting polymer-, metal oxide-, and carbon nanotube-based composite electrode materials for supercapacitors: a review

“…Panwar et al have reported a MoS 2 /graphene-based electrode material for ultrathin SCs. 258 They used the field effect transistor (FET) concept in their SCs. They prepared a few atomic thick layers of MoS 2 /graphene in FET-based SCs.…”

“…Panwar et al have fabricated FET-based SCs comprised of MoS 2 /graphene. 258 They compared the electrochemical performance of ultrathin SCs with that of MoS 2 and graphene electrode material-based SCs. They observed that electrochemical performance increases almost 1000 times when combining MoS 2 /graphene.…”

Substrate Versatile Roller Ball Pen Writing of Nanoporous MoS2 for Energy Storage Devices

“…Further, the avenue of the electrochemical microsupercapacitor has been explored in field-effect transistor (FET) device geometries with the use of 2D materials wherein direct pen writing can simplify the fabrication process further to make customizable energy storage devices with superior performance. 27 The emerging class of layered 2D transition metal dichalcogenides remains untraversed in this domain of direct pen writing toward electronic and energy storage devices such as supercapacitors and batteries. In addition to the direct writing of 2D materials, fabricating them in the form of porous structures is also important as the aspect of nanoporosity will certainly intend to develop a potential electrode material.…”

“…Recently, extrusion-based direct ink writing of one-dimensional (1D) nanostructures such as carbon nanotubes and a variety of materials in complex 3D structures has gained significant attention for flexible conductors, circuits, sensors and actuators, soft robotics, electronic devices, and components. , Some of this acquired knowledge and applications might be easily translated to much simpler direct pen writing to enable customizable designs in the hands of the end user. Further, the avenue of the electrochemical microsupercapacitor has been explored in field-effect transistor (FET) device geometries with the use of 2D materials wherein direct pen writing can simplify the fabrication process further to make customizable energy storage devices with superior performance . The emerging class of layered 2D transition metal dichalcogenides remains untraversed in this domain of direct pen writing toward electronic and energy storage devices such as supercapacitors and batteries.…”