Combined Experimental and Theoretical Insights into Energy Storage Applications of a VO₂(D)–Graphene Hybrid

Abstract

In this work, a rare VO2(D) phase plate-like structures and integrated with graphene [reduced graphene oxide (rGO)/VO2(D)] has been developed by facile hydrothermal route, explored their activity towards supercapacitor application and validated by the extensive ab initio simulations using density functional theory (DFT) study. After successful synthesis, the samples have been characterized by various techniques to know their crystal phase, surface morphology, and elemental composition. The energy storage performance of these electrode materials was studied by both symmetric and asymmetric supercapacitor devices. In a symmetric supercapacitor device, the hybrid material shows a high specific capacitance of 737 F g–1 at a scan rate of 1 mV s–1 and 244 F g–1 at a current density 1 A g–1 with an excellent cycle life of over 5000 cycles without any capacitance loss. Further, an asymmetric coin-cell supercapacitor device has been fabricated by using rGO as a negative electrode and the rGO/VO2(D) hybrid as a positive electrode. The energy storage performance was measured at a wide potential of 2 V, and the powering of a light-emitting diode has been demonstrated. The DFT simulations predict that the significant synergistic effect on enhanced capacitance can be attributed to orbital interactions and enhancement of electronic states near the Fermi level because of additional C 2p states from graphene.

Synthesis, Characterizations, and Electrochemical Performances of Highly Porous, Anhydrous Co0.5Ni0.5C2O4 for Pseudocapacitive Energy Storage Applications

“…According to the charge storage mechanism, pseudocapacitors have access to different oxidation states for redox charge transfer that can enable higher energy density compared to EDLC. , To increase higher energy density, an asymmetry cell shows better performance when the capacitor component stores electrochemical energy by electrostatic force, and the battery component enhances the electron transfer in the hybrid electrode system, which leads to better charge transfer reaction at high current rates . Many studies are being carried out on transition metal oxide-based materials such as NiO, V 2 O 5 , spinel Co 3 O 4 , Fe 2 O 3 , and mixed spinel NiCo 2 O 4 to explore electrodes for the pseudocapacitor. − However, structural instability and performance degradation issues related to transition metal oxide lead to investigation of the novel framework structure for higher surface charge storage and better structural stability. − Metal–organic frameworks (MOFs) are used as an interesting open framework structure, where materials are constructed by joining metal-containing units with organic linkers, generating an interesting three-dimensional or two-dimensional network with permanent porosity . Highly porous metal–organic framework structures, especially utilizing an oxalate linker with active participation metal ion redox, are known to show faradic pseudocapacitive characteristics. − However, most of the oxalate materials have a high open structural space to accommodate the hydration of water, and that is why, most of the transition metal oxalates contain a structural water molecule.…”

A Rational Fabrication Method for Low Switching-Temperature VO2

“…Besides the single valence vanadium oxides, such as VO, V O , VO and V O , several mixed valence states exist which can be grouped into Magneli series (V O ) between VO and V O phases and Wadsley series (V O ) between V O and VO 2 phases. Vanadium-oxides are known by their wide range of applications from catalyst to energy storage [ 1 , 2 , 3 ]; however, one of their most remarkable features is the semiconductor to metal transition (SMT), due to external stimuli, i.e., temperature or electric field. The electrical conductivity of many vanadium-oxides changes several orders of magnitude as the transition temperature is crossed.…”

An Overview of Coating Processes on Metal Substrates Based on Graphene-Related Materials for Multifarious Applications

“…Metal oxide nanoparticles templated on RGO have been explored as suitable for electrode applications in supercapacitors and LIBs . Graphene-based metal nanoparticles , and metal oxide nanoparticles hybrids such as GeO 2 , MnO 2 , CuO 2 , Mn 3 O 4 , VO 2 (D) phase, V 10 O 14 (OH) 2 , NiCo 2 O 4 , ZnCo 2 O 4 , and CoMoO 4 , and N,S co-doped carbon quantum dots (N,S-CQDs) have potential toward energy storage and energy conversion applications. High-performance electrodes have been developed by synthesizing hybrid structures using GRMs and metal oxide NPs via EPD, dip coating, and hydrothermal methods on Ni, SS, and Cu substrates.…”