Topic
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.
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TL;DR: It was found that the soluble COD (SCOD) removal efficiencies remained over 90% throughout the operational period, mainly because of methanogenic activity, which accounted for 35 to 58% of the SCOD removed at a loading rate of 1.0 g COD/L/ day.
Abstract: The upflow microbial fuel cell (UMFC) was developed to generate electricity while simultaneously treating wastewater. During a five-month period of feeding a sucrose solution as the electron donor, the UMFC continuously generated electricity with a maximum power density of 170 mW/m2. To achieve this power density, the artificial electron-mediator hexacyanoferrate was required in the cathode chamber. The power density increased with increasing chemical oxygen demand (COD) loading rates up to 2.0 g COD/ L/day after which no further increases in power density were observed, indicating the presence of limiting factors. The overarching limiting factor for the UMFC in this study was the internal resistance, which was estimated as 84 omega at the maximum power density, and restricted the power output by causing a significant decrease in operating potential. Low Coulombic efficiencies varying from 0.7 to 8.1% implied that the electron-transfer bacteria were incapable of converting all of the available organics into electricity, so the excessive substrate created niches for the growth of methanogens. We found that the soluble COD (SCOD) removal efficiencies remained over 90% throughout the operational period, mainly because of methanogenic activity, which accounted for 35 to 58% of the SCOD removed at a loading rate of 1.0 g COD/L/ day. Additionally, transport limitation due to insufficient substrate diffusion was shown by cyclic voltammetry (CV).
767 citations
TL;DR: In this article, the authors discuss the recent work at the Pacific Northwest National Laboratory (PNNL) in support of the design and development of low-cost modular solid oxide fuel cells using lower temperature, anode-supported SOFCs.
737 citations
TL;DR: The performance of a single-chamber solid oxide fuel cell was studied using a ceria-basedsolid electrolyte at temperatures below 773 kelvin, where the solid electrolyte functioned as a purely ionic conductor.
Abstract: The performance of a single-chamber solid oxide fuel cell was studied using a ceria-based solid electrolyte at temperatures below 773 kelvin. Electromotive forces of ∼900 millivolts were generated from the cell in a flowing mixture of ethane or propane and air, where the solid electrolyte functioned as a purely ionic conductor. The electrode-reaction resistance was negligibly small in the total internal resistances of the cell. The resulting peak power density reached 403 and 101 milliwatts per square centimeter at 773 and 623 kelvin, respectively.
675 citations
TL;DR: The asymmetric supercapacitor fabricated with high energy and power densities using graphene hydrogel with 3D interconnected pores as the negative electrode and vertically aligned MnO(2) nanoplates on nickel foam as the positive electrode in a neutral aqueous Na( 2)SO(4) electrolyte presents stable cycling performance with 83.4% capacitance retention after 5000 cycles.
Abstract: We have successfully fabricated an asymmetric supercapacitor with high energy and power densities using graphene hydrogel (GH) with 3D interconnected pores as the negative electrode and vertically aligned MnO2 nanoplates on nickel foam (MnO2-NF) as the positive electrode in a neutral aqueous Na2SO4 electrolyte. Because of the desirable porous structure, high specific capacitance and rate capability of GH and MnO2-NF, complementary potential window of the two electrodes, and the elimination of polymer binders and conducting additives, the asymmetric supercapacitor can be cycled reversibly in a wide potential window of 0–2.0 V and exhibits an energy density of 23.2 Wh kg–1 with a power density of 1.0 kW kg–1. Energy density of the asymmetric supercapacitor is significantly improved in comparison with those of symmetric supercapacitors based on GH (5.5 Wh kg–1) and MnO2-NF (6.7 Wh kg–1). Even at a high power density of 10.0 kW kg–1, the asymmetric supercapacitor can deliver a high energy density of 14.9 Wh k...
670 citations
TL;DR: This work constitutes the first demonstration of using VN nanowires as high energy anode, which could potentially improve the performance of energy storage devices.
Abstract: To push the energy density limit of asymmetric supercapacitors (ASCs), a new class of anode materials is needed. Vanadium nitride (VN) holds great promise as anode material for ASCs due to its large specific capacitance, high electrical conductivity, and wide operation windows in negative potential. However, its poor electrochemical stability severely limits its application in SCs. In this work, we demonstrated high energy density, stable, quasi-solid-state ASC device based on porous VN nanowire anode and VOx nanowire cathode for the first time. The VOx//VN-ASC device exhibited a stable electrochemical window of 1.8 V and excellent cycling stability with only 12.5% decrease of capacitance after 10 000 cycles. More importantly, the VOx//VN-ASC device achieved a high energy density of 0.61 mWh cm–3 at current density of 0.5 mA cm–2 and a high power density of 0.85 W cm–3 at current density of 5 mA cm–2. These values are substantially enhanced compared to most of the reported quasi/all-solid-state SC devices...
665 citations