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.

Waste heat energy harvesting using the Olsen cycle on 0:945Pb.Zn 1=3 Nb 2=3 /O 3 - 0:055PbTiO 3 single crystals

Abstract: This paper reports on direct thermal to electrical energy conversion by performing the Olsen (or Ericsson) cycle on [001]-poled 0:945PbZn1=3Nb2=3O3‐0:055PbTiO3 (PZN-5.5PT) single crystals. The cycle consists of two isothermal and two constant electric field processes. The energy density was found to decrease with increasing cycle frequency while the power density increased. The maximum energy density obtained was 150 J=l=cycle for temperatures between 100 and 190 C and electric field between 0 and 1:2 MV m 1 at frequency 0.034 Hz. The maximum power density reached 11:7 W l 1 at 0.1 Hz for temperatures between 100 and 190 C and electric fields between 0.2 and 1:5 MV m 1 . Moreover, the dielectric constant and saturation polarization of PZN-5.5PT are reported for the first time at 0.1 Hz for temperatures between 100 and 190 C. Finally, the experimental results agree relatively well with predictions by a recently developed temperature-dependent property model already validated with PMN-32PT. Inter-sample variability and sample durability are also discussed. (Some figures may appear in colour only in the online journal)

Modes in a pulse-modulated radio-frequency dielectric-barrier glow discharge

Abstract: This letter reports an experimental study of a pulse-modulated radio-frequency dielectric-barrier discharge in atmospheric helium. By controlling the duty cycle at a modulation frequency of 10 and 100kHz, the 13.56MHz discharge is shown to operate in three different glow modes: the continuum mode, the discrete mode, and the transition mode. By investigating plasma ignition, residual electrons during power off are found to affect different glow modes. Duty cycle dependences of power density, gas temperature, optical emission intensities at 706 and 777nm are used to capture clearly the characteristics of the three glow modes.

Hierarchical nickel nanowire@NiCo2S4 nanowhisker composite arrays with a test-tube-brush-like structure for high-performance supercapacitors

Abstract: Well-ordered, hierarchical and nanostructured composite electrodes have gained tremendous research attention for energy storage applications, because of their highly efficient electron and ion transport channels and abundant electrochemically active sites. However, it still remains a great challenge to prepare such architectures on a large scale with high active material mass loadings for making better use of the whole electrode area. Herein, needle-like NiCo2S4 nanowhiskers are radially grown on a uniform nickel nanowire array (NNA), forming a unique densely packed test-tube-brush-like nanostructure. Since these NiCo2S4 nanowhiskers are intrinsically highly electrically conductive, the hierarchical electrode structure can drastically elevate the charge transport ability in the whole electrode region; additionally, it can greatly help to release stresses at micro- and nano-scales, leading to robust mechanical flexibility and superior energy storage capability. Experimental results show that this composite array electrode exhibits an ultrahigh specific capacitance of 1523 F g−1 at a mass loading of 4.03 mg cm−2 at a current density of 1 A g−1, and a rate capability of 61.8% from 1 to 40 A g−1, together with a superior cycle stability with 92.4% capacitance retention after 20 000 cycles at a current density as high as 10 A g−1. An asymmetric supercapacitor consisting of a NNA@NiCo2S4 (NNANCS) cathode and activated carbon (AC) anode delivers a maximum energy density of 47.29 W h kg−1 at a power density of 793.5 W kg−1 and still delivers an energy density of 29.50 W h kg−1 at a maximum power density of 27.64 kW kg−1. This work may inspire new ideas for constructing high-performance electrodes for energy storage.