Hybridizing Energy Conversion and Storage in a Mechanical-to-Electrochemical Process for Self-Charging Power Cell.
ABSTRACT Energy generation and energy storage are two distinct processes that are usually accomplished using two separated units designed on the basis of different physical principles, such as piezoelectric nanogenerator and Li-ion battery; the former converts mechanical energy into electricity, and the latter stores electric energy as chemical energy. Here, we introduce a fundamental mechanism that directly hybridizes the two processes into one, in which the mechanical energy is directly converted and simultaneously stored as chemical energy without going through the intermediate step of first converting into electricity. By replacing the polyethylene (PE) separator as for conventional Li battery with a piezoelectric poly(vinylidene fluoride) (PVDF) film, the piezoelectric potential from the PVDF film as created by mechanical straining acts as a charge pump to drive Li ions to migrate from the cathode to the anode accompanying charging reactions at electrodes. This new approach can be applied to fabricating a self-charging power cell (SCPC) for sustainable driving micro/nanosystems and personal electronics.
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ABSTRACT: Flexible energy-storage devices are attracting increasing attention as they show unique promising advantages, such as flexibility, shape diversity, light weight, and so on; these properties enable applications in portable, flexible, and even wearable electronic devices, including soft electronic products, roll-up displays, and wearable devices. Consequently, considerable effort has been made in recent years to fulfill the requirements of future flexible energy-storage devices, and much progress has been witnessed. This review describes the most recent advances in flexible energy-storage devices, including flexible lithium-ion batteries and flexible supercapacitors. The latest successful examples in flexible lithium-ion batteries and their technological innovations and challenges are reviewed first. This is followed by a detailed overview of the recent progress in flexible supercapacitors based on carbon materials and a number of composites and flexible micro-supercapacitors. Some of the latest achievements regarding interesting integrated energy-storage systems are also reviewed. Further research direction is also proposed to surpass existing technological bottle-necks and realize idealized flexible energy-storage devices.Advanced Materials 06/2014; 26(28). · 15.41 Impact Factor
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ABSTRACT: α-Fe2 O3 nanoparticles are uniformly coated on the surface of α-MoO3 nanorods through a two-step hydrothermal synthesis method. As the anode of a lithium-ion battery, α-Fe2 O3 @α-MoO3 core-shell nanorods exhibit extremely high lithium-storage performance. At a rate of 0.1 C (10 h per half cycle), the reversible capacity of α-Fe2 O3 @α-MoO3 core-shell nanorods is 1481 mA h g(-1) and a value of 1281 mA h g(-1) is retained after 50 cycles, which is much higher than that retained by bare α-MoO3 and α-Fe2 O3 and higher than traditional theoretical results. Such a good performance can be attributed to the synergistic effect between α-Fe2 O3 and α-MoO3 , the small size effect, one-dimensional nanostructures, short paths for lithium diffusion, and interface spaces. Our results reveal that core-shell nanocomposites have potential applications as high-performance lithium-ion batteries.Chemistry - An Asian Journal 08/2014; · 4.57 Impact Factor
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ABSTRACT: We report on the electrospinning of poly(vinylidene fluoride– hexafluoropropylene) [P(VDF–HFP)] nanofibers doped with silver nanoparticles for the preparation of a polymer based nanogenerator (PNG). It has been found that the yield of the piezoelectric phase is increased by the addition of silver nanoparticles. Furthermore, defects in the P(VDF–HFP) electrospun fibers are removed resulting in a significant enhancement in the output power of the PNG. A maximum generated PNG output voltage of 3 V with a current density of 0.9 lA cm2 is achieved.Physical Chemistry Chemical Physics 02/2014; · 4.20 Impact Factor