We report a new fabrication method for a fully stretchable supercapacitor based on single wall carbon nanotube (SWCNT)-coated electrospun rubber nanofibers as stretchable supercapacitor electrodes. The deposition conditions of SWCNT on hydrophobic rubber nanofibers are experimentally optimized to induce a uniform coating of SWCNT. For surfactant-assisted coating of SWCNT, both water contact angle and sheet resistance were lower compared to the cases with other surface treatment methods, indicating a more effective coating approach. The excellent electromechanical properties of this electrode under stretching conditions are demonstrated by the measurement of Young’s modulus and normalized sheet resistance. The superb tolerance of the electrode with respect to stretching is the result of (i) high aspect ratios of both nanofiber templates and the SWCNT conductors, (ii) the highly elastic nature of rubbery nanofibers, and (iii) the strong adherence of SWCNT-coated nanofibers on the elastic ecoflex substrate. Electrochemical and electromechanical measurements on stretchable supercapacitor devices reveal that the volumetric capacitance (15.2 F cm−3 at 0.021 A cm−3) of the unstretched state is maintained for strains of up to 40%. At this level of strain, the capacitance after 1,000 charge/discharge cycles was not significantly reduced. The high stability of our stretchable device suggests potential future applications in various types of wearable energy storage devices.
Lithium-ion polymer batteries of aluminium-laminated packaging structure have advantages in terms of thermal characteristics and safety but have a weak configuration with respect to external forces compared with other types of cells such as cylindrical and prismatic cells. Thus it is important to protect the batteries of the aluminium-laminated packaging structure under the severe conditions encountered in vehicle operation where excessive mechanical impacts and vibrations may affect the battery system. In this work, an energy storage system for a hybrid electric vehicle (HEV) has been developed using lithium-ion polymer battery cells with an aluminium-laminated packaging structure and has been tested for structural and electrical durabilities. The test results of combined accelerated vibration and charge-discharge cycling are presented to prove that the battery pack has the durability to satisfy vehicle standards. Three different types of test method have been applied to evaluate the mechanical and electrical durabilities. It was observed that the HEV battery pack satisfied the durability standards required for vehicle applications. The results imply that an aluminiumlaminated cell packaging structure can be a competitive option for physical configuration of cells for vehicle applications.
A series of hydrogen-based TiO2 photocatalysts were prepared by the simple entrapment of TiO2 nanoparticles in different hydrogel matrices using gelation processes. The hydrogels, namely, agarose, alginate, and chitosan, were used as matrices for TiO2 immobilization. Morphological differences were characterized for the three different hybrid gel photocatalysts. The rate of methylene blue (MB) photodegradation increased with increasing initial TiO2 dosage in all samples. The structural properties of the hydrogels significantly affected the diffusion of MB and altered the photocatalytic activities. Among these three different hybrid gel photocatalysts, the chitosan-based TiO2 membrane showed superior activity to the agarose- and alginate-based TiO2 hybrid gels. In addition, chitosan/TiO2 still showed excellent photocatalytic activity after being reused in three cycles, suggesting that chitosan/TiO2 is a new potential eco-friendly and a cost-effective photocatalyst for wastewater treatment.
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