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Optimization of suitable electrode material flashing high electrochemical performance is the main hindrance in energy storage applications. Metal oxide-based electrode materials are promising candidate which greatly promotes the sustainable development. Herein, strontium oxide (SrO) is synthesized from sonochemical method followed by calcination. Incorporating polyaniline (PANI) and graphene (Gr) intensify the materials performance. Three asymmetric devices are designed using SrO, its composites (SrO/PANI and SrO/PANI/Gr) and activated carbon (AC) as an electrode and electrolyte-soaked separators are sandwiched in solidly packed cell assembly. Electrochemical measurements are performed to scrutinize the inherent properties. After that, Dunn’s model is applied to evaluate the capacitive and diffusion-controlled contributions. The obtained result divulges that SrO/PANI/Gr//AC exhibits more diffusive-controlled contribution and reveals a battery type behavior due to the contribution of PANI in redox reactions. Thus, this work delivers a route to synthesize metal oxides-based composites and a systematic approach to analyze the charge storage mechanism in asymmetric supercapacitors.

A series of cobalt manganese sulfide (CoMnS) grown directly on Ni foam substrate via co-electrodeposition technique to study an appropriate choice of deposition cycle numbers of cyclic voltammetry at a fixed scan rate. The binder free electrodes have been fabricated from a quick synthesis methodology by evaluating the binary metal sulfides for achieving an extremely high energy storage. By carefully selecting the synthesis methodology and ingredients, CoMnS displayed an excellent electrical conductivity and low internal resistance, which makes them a promising contender for energy storage applications. S2 electrode having 12 number of deposition cycles portrayed high electrochemical performance enactment by means of 2297 F/g specific capacitance from cyclic voltammetry (CV) at 3 mV/s, while 2291 F/g from galvanostatic charge discharge (GCD) at 10 A/g. The S2 electrode have smaller ESR value calculated from EIS analysis that elucidated high conductance. Furthermore, the hybrid supercapacitor device was formed by sandwiching activated carbon (negative electrode) with S2 electrode (positive electrode) detached thru 1 M KOH electrolyte drenched permeable membrane. The electrochemical characterizations of device resulted an outstanding specific energy of 106 Wh/kg at 5 A/g, specific power of 24,000 W/kg at 30 A/g and reveals an excellent capacitance retentivity of 94% at room temperature after 2500 GCD cycles. This study suggested that 12 cycle numbers for deposition are optimized as an appropriate mass loaded for superior electrochemical energy storage applications.

Asymmetric devices are fabricated by cramming the active material Co3O4/C composite (positive electrode) with activated carbon (negative electrode). Devices are examined under aqueous and gelled electrolyte. The theoretical model is adopted to study the charge storage mechanism in two devices. It has been observed that the capacitive and diffusion-controlled contribution of electrode material is affected by the phase change of electrolyte. Diffusive contribution is prominent in case of 1 M KOH aqueous electrolyte while more capacitive contribution has been noticed in PVA-KOH-C gelled electrolyte. By changing the phase of electrolyte, the potential window is enhanced which upsurges the energy density of device. For commercial applications, solid state device exhibits more energy storage and have high safety standards than aqueous electrolyte-based devices.

A systematic approach has been employed to statistically analyze the Faradaic and non-Faradaic mechanism on electrodes. Two strategies have been adopted for device design, i.e. symmetric and asymmetric, by using the metal oxide synthesized via sonochemical method and activated carbon electrode. Structural and electrochemical characterization have been performed to investigate the morphological and electrochemical properties of electrode material. Both devices are electrochemically examined by using cyclic voltammetry (CV) and Galvanostatic charge discharge (GCD) measurements to evaluate the electrochemical performance. CV curves are further explored to study the capacitive and diffusive contribution in both devices. The diffusive-controlled contribution at low scan rate in asymmetric device is about 65% which is suitable for supercapattery applications while the symmetric device shows 91% diffusive contribution presenting better performance for battery applications. The strategy unveils the high capacitive and diffusive contribution in asymmetric and symmetric devices, respectively. Results reveal that same material can be exploited for supercapattery and battery applications by implementing different device architectures.

The excellent solution-processability of polymers have provoked the interest for their potential applications in cost-effective electronic devices. However, these devices usually have low mobility. The study manifests an innovative approach to enhance the mobility of polymer-based field effect transistors (FETs) by incorporating graphene as an intervening layer between poly [4-(4,4-dihexadecyl-4H-cyclopenta [1,2-b:5,4b′] dithiophen-2-yl)-alt-[1,2,5] thiadiazolo [3,4-c] pyridine] (PCDTPT) channel and dielectric layer dielectric. An intentional discontinuity in the graphene layer was introduced to affirm the role of polymer as channel and graphene as carrier injector. The results divulge the enhancement in the performance of PCDTPT-graphene and PCDTPT-graphene (discontinuous) device as compare to pristine PCDTPT based FET. A significantly high mobility i.e. 13.08 cm2/V.sec is achieved for PCDTPT-graphene hybrid device which is 32 times higher than that of pristine PCDTPT based FET (0.41 cm2/V.sec). These results signify that the incorporation of atomically thin graphene layer is a novel route for fabrication of high mobility solution-processed polymer-based FETs for next generation cost effective and high performance electronic devices.

Two dimensional (2D) materials based heterostructures have gained profound interest in optoelectronics and electronic technology due to additional functionalities over the individual structures. This study demonstrates the fabrication and characterization of van der Waal heterostructure by selective coverage of graphene (Gr) with tungsten disulfide (WS2). The electrical transport measurements divulge the tweaking of charge carriers in graphene after WS2 coverage. Such architecture provides route towards the formation of heterojunction within graphene FET based on surface charge transfer between Gr/WS2 heterointerface. Furthermore, the exposure of device towards deep ultraviolet light (DUV) enhances the charge transfer mechanism and as a result more pronounced junction is observed. The photoelectrical characterization of heterostructure is also investigated by calculating detectivity (D*), external quantum efficiency (EQE) photoresponsivity (Rλ). Our results suggest that 2D heterostructures in combination with DUV irradiations are more efficient and suitable choice to selectively tune the properties of 2D material-based optoelectronic devices.