We report a novel configuration of symmetrical electric double-layer capacitors (EDLCs) comprising a plastic crystalline succinonitrile (SN) based flexible polymer gel electrolyte, incorporated with sodium trifluoromethane sulfonate (NaTf) immobilised in a host polymer poly (vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP). The cost-effective activated carbon powder possessing a specific surface area (SSA) of ? 1700 m2g-1 containing a large proportion of meso-porosity has been derived from tea waste to use as supercapacitor electrodes. The high ionic conductivity (?3.6�10-3 S cm-1 at room temperature) and good electrochemical stability render the gel polymer electrolyte film a suitable candidate for the fabrication of EDLCs. The performance of the EDLCs has been tested by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge-discharge studies. The performance of the EDLC cell is found to be promising in terms of high values of specific capacitance (?270 F g-1), specific energy (? 36 Wh kg-1), and power density (? 33 kW kg-1).

EDLC was fabricated using hybrid solid polymer electrolyte from PVA-diapers and an activated carbon powder as electrode by using solution casting method. For comparison, four types of EDLC cells were constructed and tested. It was found that an EDLC with a PVA-diapers (60:40) polymer electrolyte exhibited much higher capacitance and longer cycle-life. The electrocapacitive properties of the supercapacitor (P50HD50, P60HD40, P70HD30 and P80HD20) were done using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge discharge (GCD). Results from these analysis showed that P60HD40 cell had recorded excellent rate capability and highest Csp value of 179 F g-1 (EIS), 50 F g-1 (CV), 328 F g-1 (GCD) respectively. Futher, results from ESR (GCD) analysis showed that P60HD40 composition of PVA/H3PO4 liquid electroyte gave a lower value of 88.05 ? in the supercapacitor cell compared with another cells.

This study investigates the effect of temperature and impregnation ratio on the physicochemical properties of activated carbon prepared from desiccated coconut residue by chemical activation using potassium hydroxide. Desiccated coconut residue sample was first carbonized at three different temperatures for 1 h at 400, 500 and 600 °C, respectively. The resulting chars were impregnated with KOH at three different impregnation ratio; 1:1, 1:2 and 1:3, respectively and activated under nitrogen atmosphere for 1 h at three different temperatures based on its carbonization temperature. The BET surface area and pore volume was strongly affected by temperature in which increased in temperature caused increased in BET surface are and pore volume. The BET surface area also increased with impregnation ratio but then decreased due to pore widening of activated carbons.

The growth of Sn:ZnO nanowires on a silicon substrate using a low thermal evaporation method is reported. A horizontal quartz tube with controlled supply of O2 gas were used to fabricate the samples where Zn and Sn metal powders were previously mixed and heated at 500°C. This allows the reactant vapours to deposit onto the substrate, which placed at a certain distance from the source materials. The samples were characterized using FESEM, EDX and HRTEM measurements. Randomly oriented nanowires were formed with varying dopant concentrations from 3 to 15 at%. It was observed that from FESEM images, when the dopant concentrations were increased, a hexagonal rod with a wire extended at its end was clearly formed and the best images of nanowires were shown at the highest concentration of 15 at% measuring between 26 to 35 nm and roughly 500 nm in diameter and length respectively. The doping process played an important role in order to alter the morphological properties of Sn:ZnO nanowires. Sn:ZnO nanowires have large potential in many applications such as in selected sensor technology including gaseous sensors, liquid sensors and others.

The main objective of the present work is to develop a high conducting hybrid solid polymer electrolyte (HSPE) using polyvinyl alcohol as the host polymer and H 3PO 4 as the ionic dopant. Owing to its porous nature, the introduction of a Whatman filter paper helps to increase the electrical conductivity by acting as a support to the electrolyte system. This allows more H 3PO 4 acid to be loaded into the system and thus helps to improve the mechanical strength of the electrolytes. The highest conducting HSPE was obtained at 1�04�10 -4 S cm -1 for samples containing 70% loading of acid (P30H70-C). Such conductivity is sufficient for application in an electrical double layer capacitor (EDLC). The EDLC was fabricated using the hybrid electrolyte with its activated carbon electrodes soaked in H 3PO 4. A specific capacitance of 34 F g -1 with internal resistance of as low as 1 ? cm -2 was obtained when the cell was charged-discharged at 10 mA. The working voltage for this EDLC is 1 V with efficiency ranging between 85 and 97%. � W. S. Maney & Son Ltd. 2011.

Binderless electrodes of activated carbon monoliths (ACMs) and its composites with graphene are prepared by carbonization and activation of green monoliths consisting of self-adhesive carbon grains and 0�10�wt% KOH-treated graphene. Compared with ACMs, the optimized composite containing 6�wt% graphene exhibits more ordered micro-structures with increased crystallite height, and graphitic sp2 carbons (ID/IG�=�0.49 vs. 0.91) along with enhanced porosity; as revealed by X-ray diffraction, Raman, and N2 adsorption-desorption studies. These modifications lead to increased electrical conductivity (13 vs. 9�S�cm?1) through improved interconnections of carbon particles by graphene, and surface area�~�(800 vs. 456�m2�g?1) due to increased inter-particle spacing. Further, contrary to ACMs, the composite electrodes can offer faster delivery of energy in almost 50% less response time (5 vs. 8�s) due to reduced equivalent series resistance (1.67 vs. 2.65�?) and charge transfer resistance (0.55 vs. 1.33�?). � 2017, Springer-Verlag GmbH Germany.