Fabrication and Characterization of Supercapacitors toward Self-Powered System

Ever increasing energy demand urges to impelled extensive research in the development of new eco-friendly energy harvesting and storage technologies. Energy harvesting technology exploiting renewable energy sources is an auspicious method for sustainable, autonomous, and everlasting operation of a variety of electronic devices. A new concept of an integrated self-powered system by combining an energy harvesting device with an energy storage device has been established to harvest renewable energy and simultaneously store it for sustainable operation of electronic devices. In this chapter, describes the fabrication of a self-powered system by integrating the supercapacitor with energy harvesting devices such as nanogenerator and solar cells to power portable electronic devices. Initially synthesis and electrochemical characterization of various electroactive materials for supercapacitors and further, fabrication of supercapacitor device were discussed. In conclusion, this chapter demonstrates self-powered system by the integration of energy harvesting, energy storage module with portable electronic devices. The various result validates the feasibility of using supercapacitors as efficient energy storage components in self-powered devices. The proposed self-powered technology based on energy conversion of renewable energy to electrical energy which stored in energy storage device and it will be used to operate several electronic devices as a self-powered device

Fiber-shaped electronic devices

Textile electronics embedded in clothing represent an exciting new frontier for modern healthcare and communication systems. Fundamental to the development of these textile electronics is the development of the fibers forming the cloths into electronic devices. An electronic fiber must undergo diverse scrutiny for its selection for a multifunctional textile, viz., from the material selection to the device architecture, from the wearability to mechanical stresses, and from the environmental compatibility to the end-use management. Herein, the performance requirements of fiber-shaped electronics are reviewed considering the characteristics of single electronic fibers and their assemblies in smart clothing. Broadly, this article includes i) processing strategies of electronic fibers with required properties from precursor to material, ii) the state-of-art of current fiber-shaped electronics emphasizing light-emitting devices, solar cells, sensors, nanogenerators, supercapacitors storage, and chromatic devices, iii) mechanisms involved in the operation of the above devices, iv) limitations of the current materials and device manufacturing techniques to achieve the target performance, and v) the knowledge gap that must be minimized prior to their deployment. Lessons learned from this review with regard to the challenges and prospects for developing fiber-shaped electronic components are presented as directions for future research on wearable electronics

Synthesis and characterization of DNA fenced, self-assembled SnO₂ nano-assemblies for supercapacitor applications

Self-assembled, aggregated, chain-like SnO2 nano-assemblies were synthesized at room temperature by a simple wet chemical route within an hour in the presence of DNA as a scaffold. The average size of the SnO2 particles and the chain diameter were controlled by tuning the DNA to Sn(II) molar ratio and altering the other reaction parameters. A formation and growth mechanism of the SnO2 NPs on DNA is discussed. The SnO2 chain-like assemblies were utilized as potential anode materials in an electrochemical supercapacitor. From the supercapacitor study, it was found that the SnO2 nanomaterials showed different specific capacitance (Cs) values depending on varying chain-like morphologies and the order of Cs values was: chain-like (small size) > chain-like (large size). The highest Cs of 209 F g−1 at a scan rate of 5 mV s−1 was observed for SnO2 nano-assemblies having chain-like structure with a smaller size. The long term cycling stability study of a chain-like SnO2 electrode was found to be stable and retained ca. 71% of the initial specific capacitance, even after 5000 cycles. A supercapacitor study revealed that both morphologies can be used as a potential anode material and the best efficiency was observed for small sized chain-like morphology which is due to their higher BET surface area and specific structural orientation. The proposed route, by virtue of its simplicity and being environmentally benign, might become a future promising candidate for further processing, assembly, and practical application of other oxide based nanostructure materials.publishe

Comprehensive insight into the mechanism, material selection and performance evaluation of supercapatteries

Electrochemical energy storage devices (EESs) play a crucial role for the construction of sustainable energy storage system from the point of generation to the end user due to the intermittent nature of renewable sources. Additionally, to meet the demand for next-generation electronic applications, optimizing the energy and power densities of EESs with long cycle life is the crucial factor. Great efforts have been devoted towards the search for new materials, to augment the overall performance of the EESs. Although there are a lot of ongoing researches in this field, the performance does not meet up to the level of commercialization. A further understanding of the charge storage mechanism and development of new electrode materials are highly required. The present review explains the overview of recent progress in supercapattery devices with reference to their various aspects. The different charge storage mechanisms and the multiple factors involved in the performance of the supercapattery are described in detail. Moreover, recent advancements in this supercapattery research and its electrochemical performances are reviewed. Finally, the challenges and possible future developments in this field are summarized

3D Hierarchically Assembled Porous Wrinkled-Paper-like Structure of ZnCo2O4 and Co-ZnO@C as Anode Materials for Lithium-Ion Batteries

Three dimensional (3D) hierarchically assembled porous transition metal oxide nanostructures are promising materials for next generation rechargeable Li-ion batteries (LIBs). Here, the controlled synthesis of 3D hierarchically porous ZnCo2O4 ``wrinkled-paper-like'' structure constructed from two-dimensional (2D) nanosheets (similar to 20 nm thick) through calcination of corresponding mixed metal carbonate intermediate is presented. The mixed metal hydroxy-carbonate intermediate with wrinkled-paper-like structure has been synthesized by a novel organic surfactant and organic solvent free protocol at reflux condition using an aqueous solution of corresponding metal salt and ammonium carbonate. Active-inactive nanocomposites of Co-ZnO@C with similar wrinkled-paper-like morphology with varying carbon content, have also been synthesized through carbonation of hydroxyl-carbonate intermediate followed by calcination (under reducing environment). Calcination of the carbon coated mixed metal carbonate results in phase separated uniform Co metal and ZnO particles embedded on carbon matrix. The results demonstrate that incorporation of similar to 23% carbon in the matrix significantly improves the performance as anode material in LIB by exhibiting high specific capacity and enhanced cycling performance. At a current density of 100 mAg(-1), it shows an excellent initial specific capacity of 527 mAhg(-1), which is maintained up to 50 cycles. In fact, a slight gradual increase in capacity with cycling has been observed

Elucidating the piezoelectric, ferroelectric, and dielectric performance of lead-free KNN/PVDF and its copolymer-based flexible composite films

Ecofriendly, reliable, and high-performance piezoelectric materials are drawing huge interest in resolving the environmental problems arising due to consumption of fossil fuel energy. Among the lead-free ferroelectrics, potassium sodium niobate (KNN, (K,Na)NbO3) is one of the most promising piezoelectric ceramics that can replace Pb(Zr,Ti)O3. In the present work, the piezoelectric performance of KNN incorporated in poly(vinylidene fluoride) (PVDF) and its copolymers, polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), has been compared. The films were fabricated by a solution casting method and were further polarized by a corona poling technique. The results confirmed that the nanocomposite film with 8 wt % KNN filler in PVDF-TrFE (PTK8) exhibited the highest F(β) value, maximum remnant polarization, and dielectric constant value than other nanocomposites. The relative β-phase contents in PTK8, PHK8, and PK8 composite films reached 85, 76, and 75.8%, respectively, indicating that KNN acts as the most suitable nucleating agent in PVDF-TrFE. Also, the piezoelectric voltage output of the PTK8-based nanogenerator was found to be remarkably higher (∼20 V) as compared to other nanocomposite-based piezoelectric nanogenerators. It also exhibited a maximum power density of 0.54 μW/cm2 that was significantly improved in comparison to other composites. This nanogenerator was found to be a promising power generation device promoting miniaturization of self-powered systems.</p

Fabrication and feasibility study of polymer-based triboelectric nanogenerator towards blue energy harvesting

The goal of this study was to investigate a new aspect of polymeric film modification used in triboelectric nanogenerators (TENGs). TENGs were fabricated using fluorinated ethylene propylene (FEP) and chemically etched nylon films. The FTIR spectra confirmed the retained polymeric nature of the modified nylon films, and the AFM results showed an improvement in the roughness of the film surfaces after chemical treatment. The as-fabricated floatable TENGs delivered an open-circuit voltage of 12 V when subjected to an external force, and could glow a few light-emitting diodes (LEDs) with water waves. The findings of this study will open new prospects for the future development and optimization of polymer-based TENGs for blue energy harvesting

Tuning of highly piezoelectric bismuth ferrite/PVDF-copolymer flexible films for efficient energy harvesting performance

BiFeO3 (BFO) is a popular multiferroic material exhibiting robust antiferromagnetic and ferroelectric properties and is a promising candidate for use in sensors and transducers. In this work, BFO piezoceramics were synthesized by a simple hydrothermal method and were incorporated into the copolymers PVDF-TrFE and PVDF-HFP to fabricate flexible nanocomposite films. BFO nanoparticles (NPs) act as nucleating agent inside the polymer matrix, thus improving the overall performance of the piezoelectric film. The phase purity of the synthesized BFO NPs was confirmed by XRD and the β-phase content of the fabricated film was calculated from FTIR analysis. The nanocomposite film PVDF-TrFE/BFO with 6 wt% filler loading (PTB6) showed better piezoelectric performance among others. The intrinsic functional properties of the composite film were evaluated by P-E (polarization-electric field) hysteresis loop test. Further, the nanocomposite film, after corona poling, was used for fabrication of a flexible piezoelectric nanogenerator (PNG). The poled films exhibited better piezoelectric as well as dielectric properties. The fabricated PTB6 based PNG generated a maximum of 18.5 V under a biomechanical finger tapping force. This study suggests that the proposed flexible device is a potential candidate for driving low-power electronic devices

Single-Step Synthesis of N-Doped Three-Dimensional Graphitic Foams for High-Performance Supercapacitors

We present a facile yet efficient single-step pyrolysis method to prepare bulk-scale high-performance N-doped 3D-graphitic foams with various length-scale pores. The iron precursors act as catalysts for the conversion of organic substances to a graphitic structure while simultaneously providing a rigid template that prevents the aggregation of organic components, and soluble polymers act as a carbon source for the formation of N-doped multilayer graphene under high-temperature and inert conditions. The 3D-graphitic foams possess highly interconnected networks composed of micro-, meso-, and macropores with a specific surface area of up to 1509 m2 g-1 and a high conductivity of 10 S m-1. The resulting 3D-graphitic foams exhibited specific capacitance values of 330 and 242 F g-1 with outstanding cycling stability (a 23% loss after 100 000 cycles for a symmetric cell) in a three-electrode system and in a symmetric cell, respectively, when used as active materials in a supercapacitor. This study suggests the great potential of bulk-scale fabricated N-doped 3D-graphitic foams with a large surface area and excellent conductivity, as well as controlled porosity, for applications in various fields