Novel chemical route for CeO2/MWCNTs composite towards highly bendable solid-state supercapacitor device

Electrode materials having high capacitance with outstanding stability are the critical issues for the development of flexible supercapacitors (SCs), which have recently received increasing attention. To meet these demands, coating of CeO2 nanoparticles have been performed onto MWCNTs by using facile chemical bath deposition (CBD) method. The formed CeO2/MWCNTs nanocomposite exhibits excellent electrochemical specific capacitance of 1215.7 F/g with 92.3% remarkable cyclic stability at 10000 cycles. Light-weight flexible symmetric solid-state supercapacitor (FSSC) device have been engineered by sandwiching PVA-LiClO4 gel between two CeO2/MWCNTs electrodes which exhibit an excellent supercapacitive performance owing to the integration of pseudocapacitive CeO2 nanoparticles onto electrochemical double layer capacitance (EDLC) behaved MWCNTs complex web-like structure. Remarkable specific capacitance of 486.5 F/g with much higher energy density of 85.7 Wh/kg shows the inherent potential of the fabricated device. Moreover, the low internal resistance adds exceptional stability along with unperturbed behavior even under high mechanical stress which can explore its applicability towards high-performance flexible supercapacitor for advanced portable electronic devices

Vanadium oxide anchored MWCNTs nanostructure for superior symmetric electrochemical supercapacitors

Proper selection of electrode material with sensible scheme is definitely significant to dodge commercial obstacles of supercapacitors. This challenge has been addressed by engineering prototype symmetric supercapacitor (SSC) device fabricated with enhanced supercapacitive vanadium (V) oxide integrated multi-walled carbon nanotubes (MWCNTs) composite as electrode material with Li-ion associating LiClO4 electrolyte. The V2O5/MWCNTs composite with nanoscale architecture has been synthesized with inexpensive and simple chemical bath deposition (CBD) method. The cyclic voltammetry of SSC device has exhibited the involvement of electrochemically active reversible redox process in the composite. The specific capacitance of 569.7 F/g at scan rate of 2 mV/s including excellent electrochemical stability of 89.2% at 4000 CV cycles have been achieved with operating potential window of 2 V. Furthermore, the device exhibits excellent energy density of 62 Wh/kg and exceptional power density of 11.5 kW/kg. The low resistive factors have driven the device towards the potential application as glowing of red LED for 10 s

V2O5 encapsulated MWCNTs in 2D surface architecture : complete solid-state bendable highly stabilized energy efficient supercapacitor device

A simple and scalable approach has been reported for O encapsulation over interconnected multi-walled carbon nanotubes (MWCNTs) network using chemical bath deposition method. Chemically synthesized O/MWCNTs electrode exhibited excellent charge-discharge capability with extraordinary cycling retention of 93% over 4000 cycles in liquid-electrolyte. Electrochemical investigations have been performed to evaluate the origin of capacitive behavior from dual contribution of surface-controlled and diffusion-controlled charge components. Furthermore, a complete flexible solid-state, flexible symmetric supercapacitor (FSS-SSC) device was assembled with O/MWCNTs electrodes which yield remarkable values of specific power and energy densities along with enhanced cyclic stability over liquid configuration. As a practical demonstration, the constructed device was used to lit the 'VNIT' acronym assembled using 21 LED's

ZnO/CuSCN nano-heterostructure as a highly efficient field emitter: a combined experimental and theoretical investigation

We report the synthesis of two-dimensional porous ZnO nanosheets, CuSCN nanocoins, and ZnO/CuSCN nano-heterostructure thin films grown on fluorine-doped tin oxide substrates via two simple and low-cost solution chemical routes, i.e., chemical bath deposition and successive ionic layer adsorption and reaction methods. Detail characterizations regarding the structural, optoelectronic, and morphological properties have been carried out, which reveal high-quality and crystalline synthesized materials. Field emission (FE) investigations performed at room temperature with a base pressure of 1 × 10–8 mbar demonstrate superior FE performance of the ZnO/CuSCN nano-heterostructure compared to the isolated porous ZnO nanosheets and CuSCN nanocoins. For instance, the turn-on field required to draw a current density of 10 μA/cm2 is found to be 2.2, 1.1, and 0.7 V/μm for the ZnO, CuSCN, and ZnO/CuSCN nano-heterostructure, respectively. The observed significant improvement in the FE characteristics (ultralow turn-on field of 0.7 V/μm for an emission current density of 10 μA/cm2 and the achieved high current density of 2.2 mA/cm2 at a relatively low applied electric field of 1.8 V/μm) for the ZnO/CuSCN nano-heterostructure is superior to the isolated porous ZnO nanosheets, CuSCN nanocoins, and other reported semiconducting nano-heterostructures. Complementary first-principles density functional theory calculations predict a lower work function for the ZnO/CuSCN nano-heterostructure (4.58 eV), compared to the isolated ZnO (5.24 eV) and CuSCN (4.91 eV), validating the superior FE characteristics of the ZnO/CuSCN nano-heterostructure. The ZnO/CuSCN nanocomposite could provide a promising class of FE cathodes, flat panel displays, microwave tubes, and electron sources

Reciprocated electrochemical and DFT investigations of iron selenide: mechanically bendable solid-state symmetric supercapacitor

Enhanced energy storing capability with the aid of unique nanostructured morphology is beneficial to enrich the effective path for the development of energy storing capability of supercapacitors. Scheming earth abundant and low-cost transitional metal selenides (TMSs) with enhanced charge transfer capability with pronounced stability is still a challenge. Herein, state of art is presented for iron selenide with nanoflakes surface architecture synthesized with aid of simple, industry-scalable, and ionic layer controlled chemical approach namely; successive ionic layer adsorption and reaction (SILAR) method. Iron selenide electrode yields capacitance of 671.7 F/g at 2 mV/s scan rate and 434.6 F/g at 2 mA/cm2 current density through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) studies, respectively with 91.9% cyclic retention at 4000 cycles. Developed bendable solid-state supercapacitor reveals remarkable power density of 5.1 kW/kg with outstanding deformation tolerance including practical demo to run small fan, demonstrating capability for advanced energy storage applications. Complementary first-principles Density Functional Theory (DFT) approach used to achieve reciprocity with experimental supercapacitive performance through the understandings of the electronic structure

Anchoring cobalt oxide nanoparticles on to the surface multiwalled carbon nanotubes for improved supercapacitive performances

The present work explored a novel, simple and low cost ‘dipping and drying’ process followed by a successive ionic layer adsorption and reaction (SILAR) method for the synthesis of cobalt oxide anchored multiwalled carbon nanotubes (Co3O4/MWNTs). Initially, MWNTs have been coated on a stainless steel substrate by a simple ‘dip and dry’ method, on which further deposition of cobalt oxide nanoparticles was carried out by the SILAR method. Our results confirm the uniform coating of Co3O4 nanoparticles having sizes less than 15 nm on the surface of MWNTs. Later, the electrochemical performance shows that, the Co3O4/MWNTs films exhibit a maximum specific capacitance of 685 F g−1 in a 2 M KOH electrolyte at a scan rate of 5 mV s−1 with high cycle stability of 73% over 5000 cycles. Moreover, lower electrochemical equivalent series resistance (11.25 mΩ) give rise to the superior performance. These results show, the potential of Co3O4/MWNTs composite electrodes in electrochemical supercapacitors.BRS is thankful to SERB, Govt. of India through sanctioned project (Do. no: SB/S2/CMP/032/2013, dated 20/12/2013).Peer Reviewe

Electrical properties of air-stable, iodine-doped carbon-nanotube-polymer composites

We report the preparation and electrical characterization of air-stable, iodine-doped single-walled carbon nanotube (SWNT)-polymer composites, which show significant enhancement in electrical conductivity by a factor of 2-5 as compared to undoped SWNT-polymer composites. The analysis of temperature dependent conductivity data reveals that the conduction of iodine-doped SWNT composites can be well described by the thermal-fluctuation-induced tunneling model. The observed substantial conductivity enhancement in iodine-doped SWNT composites can be attributed to two factors: the higher conductivity of doped SWNTs and the smaller insulating polymer barriers between adjacent conductive SWNTs. © 2007 American Institute of Physics

MoS2 ultrathin nanoflakes for high performance supercapacitors: Room temperature chemical bath deposition (CBD)

Homogeneous ultrathin nanoflakes of MoS2 thin films have been successfully developed by simple and low cost room temperature chemical bath deposition (CBD) method which further applied as electrode material for high-performance supercapacitors. The surface morphological analysis revealed uniform growth of MoS2 nanoflakes on whole substrate surface. Structural analysis confirms the formation of rhombohedral crystal structure of MoS2. The electrochemical performances were tested by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance techniques. Different electrolytes were tested in order to find suitable electrolyte for MoS2 thin films. In addition, the effect of electrolyte concentrations on supercapacitive properties of MoS2 thin film was investigated. Thus, MoS2 ultrathin nanoflakes electrode exhibits excellent electrochemical performances with maximum specific capacitance of 576 F g−1 at 5 mV s−1 and good cycling stability of 82% over 3000 cycles.BRS and SSK would like to thank the SERB project, Govt. of India (Do. No. SB/S2/CMP/032/2013; 04/06/2013).Peer Reviewe

The electrochemical kinetics of cerium selenide nano-pebbles: The design of a device-grade symmetric configured wide-potential flexible solid-state supercapacitor

Next-generation portable flexible electronic appliances require liquid-free energy storage supercapacitor devices to eliminate leakage and to support mechanical bending that is compatible with roll-to-roll technologies. Hence, a state-of-the-art process is presented to design a solid-state, wide-potential and flexible supercapacitor through the use of nano-pebbles of cerium selenide via a simple successive ionic layer adsorption and reaction (SILAR) method that could allow an industry scalable route. We strongly believe that this is the first approach amongst physical and chemical routes not only for synthesizing cerium selenide in thin-film form but also using it for device-grade supercapacitor applications. The designed solid-state symmetric supercapacitor assembled from cerium selenide electrodes sandwiched by PVA–LiClO4 gel electrolyte attains a wide potential window of 1.8 V with capacitance of 48.8 F g−1 at 2 mV s−1 and reveals excellent power density of 4.89 kW kg−1 at an energy density of 11.63 W h kg−1. The formed device is capable of 87% capacitive retention even at a mechanical bending angle of 175°. Lighting up a strip of 21 parallel connected red LEDs clearly demonstrates the practical use of the designed symmetric solid-state supercapacitor, aiming towards the commercialization of the product in the future.The authors gratefully acknowledge DST/TMD/MES/2k16/09 project, Government of India

Nickel cobaltite as an emerging material for supercapacitors: An overview

Supercapacitor (SCs) with excellent power and reasonably high energy densities are becoming a perfect solution towards the recent demand of various energy storage applications. Present review is focused on the synthetic methods used for spinel NiCo2O4 nanomaterials with different mysterious architectures for supercapacitor application. Synthesis of different nanostructures, hetero-structures, chemical modification and incorporation with high surface area conductive nanoarchitectures are the major strategies in the development of recent high-performance NiCo2O4-based electrodes for supercapacitors. This review runs through the creativity of current science when it comes to these nano-architectured electrodes. It is organized by techniques used for synthesis including chemical methods with and without templates along with their electrochemical supercapacitive properties. Plentiful works reviewed in this review shown enhanced electrochemical performance in the spinel NiCo2O4-based electrode materials. Finally, the future research directions and the remaining challenges toward the fabrication of different nanostructured NiCo2O4-based electrode materials for next-generation SCs are discussed (224 references).The authors appreciate the award of a Humboldt Fellowship of the Alexander von Humboldt Foundation (AvH), Germany and the award of a Marie-Curie Fellowship through Beatriu de Pinos Program (BP-DGR-2013) for Catalan System of Science and Technology, Spain.Peer Reviewe