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Power density

About: Power density is a research topic. Over the lifetime, 9534 publications have been published within this topic receiving 197264 citations. The topic is also known as: volumic power & volume power density.


Papers
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Journal ArticleDOI
TL;DR: In this paper, Niobium nitride/nitrogen-doped graphene nanosheet hybrid materials are prepared by a simple hydrothermal method combined with ammonia annealing and their electrochemical performance is reported.
Abstract: Niobium nitride/nitrogen-doped graphene nanosheet hybrid materials are prepared by a simple hydrothermal method combined with ammonia annealing and their electrochemical performance is reported. It is found by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that the as-obtained niobium nitride nanoparticles are about 10-15 nm in size and homogeneously anchored on graphene. A non-aqueous lithium-ion capacitor is fabricated with an optimized mass loading of activated carbon cathode and the niobium nitride/nitrogen-doped graphene nanosheet anode, which delivers high energy densities of 122.7-98.4 W h kg(-1) at power densities of 100-2000 W kg(-1), respectively. The capacity retention is 81.7% after 1000 cycles at a current density of 500 mA g(-1). The high energy and power of this hybrid capacitor bridges the gap between conventional high specific energy lithium-ion batteries and high specific power electrochemical capacitors, which holds great potential applications in energy storage for hybrid electric vehicles.

60 citations

Journal ArticleDOI
TL;DR: In this paper, the authors numerically demonstrate near-field planar Thermo-PhotoVoltaic systems with very high efficiency and output power, at large vacuum gaps, at high temperature.
Abstract: We numerically demonstrate near-field planar ThermoPhotoVoltaic systems with very high efficiency and output power, at large vacuum gaps. Example performances include: at 1200 °K emitter temperature, output power density 2 W/cm2 with ~47% efficiency at 300 nm vacuum gap; at 2100 °K, 24 W/cm2 with ~57% efficiency at 200 nm gap; and, at 3000 °K, 115 W/cm2 with ~61% efficiency at 140 nm gap. Key to this striking performance is a novel photonic design forcing the emitter and cell single modes to cros resonantly couple and impedance-match just above the semiconductor bandgap, creating there a ‘squeezed’ narrowband near-field emission spectrum. Specifically, we employ surface-plasmon-polariton thermal emitters and silver-backed semiconductor-thin-film photovoltaic cells. The emitter planar plasmonic nature allows for high-power and stable high-temperature operation. Our simulations include modeling of free-carrier absorption in both cell electrodes and temperature dependence of the emitter properties. At high temperatures, the efficiency enhancement via resonant mode cross-coupling and matching can be extended to even higher power, by appropriately patterning the silver back electrode to enforce also an absorber effective surface-plasmon-polariton mode. Our proposed designs can therefore lead the way for mass-producible and low-cost ThermoPhotoVoltaic micro-generators and solar cells.

60 citations

Patent
09 Aug 2005
TL;DR: In this paper, a multi-engine locomotive includes at least one converter to convert mechanical energy outputted by the engines to Direct Current (DC) electrical energy, a traction motor, and a DC bus connected to the engines, converter, and traction motor.
Abstract: In one embodiment, a multi-engine locomotive includes at least one converter to convert mechanical energy outputted by the engines to Direct Current (DC) electrical energy, a traction motor, and a DC bus connected to the engines, converter, and traction motor. The engines are configured to provide a power-per-length and/or power density that is greater than the power-per-length and/or power density of a single-engine locomotive having a power rating approximately the same as the cumulative power rating of the engines in the multi-engine locomotive.

60 citations

Journal ArticleDOI
TL;DR: In this article, Li-ion capacitors (LICs) are regarded as a promising next-generation energy storage system because of their superior energy density, high power output, and prolonged cyclic life.
Abstract: Lithium-ion capacitors (LICs) are regarded as a promising next-generation energy storage system because of their superior energy density, high power output, and prolonged cyclic life. However, the ...

60 citations

Journal ArticleDOI
TL;DR: In this paper, high-power pulsed dc magnetron discharges for ionized sputtering of titanium films were investigated using a strongly unbalanced magnetron source with a planar titanium target of 100 mm diameter.
Abstract: High-power pulsed dc magnetron discharges for ionized sputtering of titanium films were investigated. The depositions were performed using a strongly unbalanced magnetron source with a planar titanium target of 100 mm diameter. The repetition frequencies were 1 and 20 kHz at 20% and 50% duty cycles and argon pressures of 0.5 and 5 Pa. Time evolutions of the discharge characteristics were measured at a target power density in a pulse up to 740 W cm−2. Time-averaged mass spectroscopy was carried out at substrate positions of 100 and 200 mm from the target. It was shown that argon ions are predominant (69–81%) in total ion fluxes onto the substrate. The Ti+ and Ar+ ion energy distributions with broadened low-energy peaks are extended to higher energies (50 eV relative to the ground potential). The ionized fraction of sputtered titanium atoms in the flux onto the substrate was in the range from 60% to 99%.

60 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023652
20221,294
2021519
2020594
2019595
2018600