Polyacrylonitrile/polyvinyl alcohol-based porous carbon nanofiber electrodes for supercapacitor applications

Porous carbon nanofibers (PCNFs) were produced from polyacrylonitrile (PAN)/polyvinyl alcohol (PVA) hybrid nanofibers with different mixing ratios and used as the free-standing, flexible, high performance electrodes for the supercapacitors. The effect of PAN/PVA ratio, PVA removing and stabilization/carbonization process on the chemical structure, and the morphology of PAN/PVA hybrid nanofibers and PCNF were investigated by Fourier transform infrared (FT-IR), field emission scanning electron microscopy (FE-SEM), and thermogravimetric analyzer (TGA). It was proved by FT-IR and FE-SEM analyses that PAN/PVA hybrid nanofibers are successfully produced and carbonized. In addition, the electrochemical performance of PCNF electrodes was analyzed by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) methods. Results showed that PCNFs exhibit higher specific capacitance and better electrochemical performance than neat carbon nanofibers (N-CNF). The specific capacitance of the EK5 PCNF (67/33 PAN/PVA wt ratio) was 157 F/g at 5 mV/s scan rate in 1 M H2SO4, while the specific capacitance of N-CNF was 96 F/g at the same conditions. Moreover, the PCNF showed excellent cyclic stability without losing performance through 2500 charge/discharge cycles at a current density of 2 A/g. As a result, free-standing, flexible, and high-performance PCNFs are excellent candidates as supercapacitor electrodes for flexible energy-storage devices

Nanofiber mat-based highly compact piezoelectric-triboelectric hybrid nanogenerators

Studies on energy generation devices for necessary energy needs have been an increasing trend all over the world as the kinds and quantities of consumer gadgets have increased. Researchers have been studying nanogenerators for the last 15 years in response to this demand. The three main reasons for these studies are increased output power, application to consumer items, and mechanical stability. Hybrid nanogenerators, on the other hand, are a method of combining at least two energy conversion mechanisms, hence reducing the need for a single conversion mechanism. In this context, while triboelectric-piezoelectric combination hybrid nanogenerators are the most popular hybrid nanogenerator class, they have several drawbacks, such as non-compact and unstable structures. As a result, for the first time, a small hybrid polymer-nanofiberbased hybrid nanogenerator concept with high output voltage and current is disclosed in this study. A hybrid nanofibrous structure was created using an electrospinning apparatus with double and triple nozzles. As a result of the periodic-compression test, the resulting nanogenerators produced a maximum voltage density of 5350 V/m2 and a current density of 5454 A/m2. By hand tapping, the resulting master unit was able to light up 119 LEDs and charge a commercial capacitor up to 0.9 V

Mechanical properties of silage covering fabrics as agrotextiles

The woven agrotextiles used in a wide variety of agricultural applications in the product cultivation and protection activities, horticulture and floriculture, aquaculture, forestry as well as animal husbandry activities have an important role to protect silages from bird/insect attacks or damages related to environmental conditions. In this study, nine different woven silage covering fabrics made of polyethylene monofilaments were designed according to desired areal porosity ratio. Afterwards, the effect of weave type and weft setting on mechanical and air permeability properties of the produced agrotextiles were investigated. The obtained results were discussed statistically. The highest values for bursting and shear strength were measured as 2.60 kN and 0.25 kN for P1 plain fabric, respectively. Twill and mat fabric structures did not burst during testing

Photovoltaic applications for textiles

Until very recently, nearly all photovoltaic devices were hard silicon semiconductor based cells and therefore they were very limited in widespread applications. Flexible polymeric semiconductors are now opening a new area in which films and fibers are becoming a potential application form. Fibers and textiles are maturing fields for photovoltaic cells with promising different applications. Photovoltaics based on textiles can positively increase the number of applications available to solar technology by delivering lightness and flexibility of photovoltaics and extending integration to other textile materials. This paper summarizes photovoltaic technology and devices including possible new uses in fibers and textiles with advanced properties

Manufacturing and Properties of Yarns Containing Metal Wires

In this work, conductive yarn manufacturing that is formed by wrapping metal wire around the cotton yarn is described. Roving material at different thicknesses and copper and stainless steel-based wires having different diameters were fed into the ring frame to produce yarns containing metal wires. Performance of the composite yarns was tested by measuring yarn count, hairiness, and tensile properties. These yarns can be used in broad application areas of smart textiles for electromagnetic shielding effectiveness, dissipation of static electric charge, or conductive textile applications

Photovoltaic properties of polymer based organic solar cells adapted for non-transparent substrates

This paper explains a semi-transparent photovoltaic device structure using polymer based materials for light harvesting. Poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C(61) butyric acid methyl ester (P3HT: PCBM) and poly(2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV:PCBM) as photoactive nano-layers were utilized and semi-transparent cells were compared with reference cells. Photoelectrical properties of developed devices were investigated. Also influencing factors of power conversion efficiency of devices were determined and possible application areas including solar harvesting textiles were discussed. (c) 2010 Elsevier Ltd. All rights reserved

A Photovoltaic Fiber Design for Smart Textiles

In this paper, the active photovoltaic fibers consisting of nano-layers of polymer-based organic compounds are presented. A flexible solar cell, including a polymer-based anode, two different nano-materials in bulk heterojunction blends as the light absorbing materials, and a semi-transparent cathode to collect the electrons, was formed by coating these materials onto flexible polypropylene (PP) fibers layer by layer, respectively, to produce electricity. Photovoltaic performances of the fibers were analyzed by measuring current versus voltage characteristics under AM1.5 conditions. The maximum value obtained as the short-circuit current density of photovoltaic fibers was 0.27 mA/cm(2). The fabrication issues and also possible smart textile applications of these photovoltaic fibers were discussed