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Engineering topics

Sprenkle, Vincent L

Publications and source records attributed to Sprenkle, Vincent L.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Methods and apparatuses for making cathodes for high-temperature, rechargeable batteries

The approaches for fabricating cathodes can be adapted to improve control over cathode composition and to better accommodate batteries of any shape and their assembly. For example, a first solid having an alkali metal halide, a second solid having a transition metal, and a third solid having an alkali metal aluminum halide are combined into a mixture. The mixture can be heated in a vacuum to a temperature that is greater than or equal to the melting point of the third solid. When the third solid is substantially molten liquid, the mixture is compressed into a desired cathode shape and then cooled to solidify the mixture in the desired cathode shape.

25 ENERGY STORAGE↗
DOE OSTI2013

Composite blend polymer membranes with increased proton selectivity and lifetime for vanadium redox flow batteries

Composite membranes based on sulfonated fluorinated poly(arylene ether) (SFPAE) and poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-co-HFP)) were prepared with various contents of P(VDF-co-HFP) for vanadium redox flow battery (VRFB) applications. The compatibility and interaction of SFPAE and P(VDF-co-HFP) were characterized by atomic force microscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The water uptake, mechanical properties, thermal property, proton conductivity, VO2+ permeability and cell performance of the composite membranes were investigated in detail and compared to the pristine SFPAE membrane. It was found that SFPAE had good compatibility with P(VDF-co-HFP) and the incorporation of P(VDF-co-HFP) increased the mechanical properties, thermal property, and proton selectivity of the materials effectively. An SFPAE composite membrane with 10 wt.% P(VDF-co-HFP) exhibited a 44% increase in VRFB cell lifetime as compared to a cell with a pure SFPAE membrane. Therefore, the P(VDF-co-HFP) blending approach is a facile method for producing low-cost, high-performance VRFB membranes.

composite↗
DOE OSTI2013

Fe/V Redox Flow Battery Electrolyte Investigation and Optimization

Recently invented Fe/V redox flow battery (IVBs) system has attracted more and more attentions due to its long-term cycling stability. In this paper, the factors (such as compositions, state of charge (SOC) and temperatures) influencing the stability of electrolytes in both positive and negative half-cells were investigated by an extensive matrix study. Thus an optimized electrolyte, which can be operated in the temperature ranges from -5oC to 50oC without any precipitations, was identified. The Fe/V flow cells using the optimized electrolytes and low-cost membranes exhibited satisfactory cycling performances at different temperatures. The efficiencies, capacities and energy densities of flow batteries with varying temperatures were discussed in detail.

Redox flow battery, Temperature stability, Electro↗
DOE OSTI2013

High Energy Density Na-S/NiCl2 Hybrid Battery

High temperature (250-350°C) sodium-beta alumina batteries (NBBs) are attractive energy storage devices for renewable energy integration and other grid related applications. Currently, two technologies are commercially available in NBBs, e.g., sodium-sulfur (Na-S) battery and sodium-metal halide (ZEBRA) batteries. In this study, we investigated the combination of these two chemistries with a mixed cathode. In particular, the cathode of the cell consisted of molten NaAlCl4 as a catholyte and a mixture of Ni, NaCl and Na2S as active materials. During cycling, two reversible plateaus were observed in cell voltage profiles, which matched electrochemical reactions for Na-S and Na-NiCl2 redox couples. An irreversible reaction between sulfur species and Ni was identified during initial charge at 280°C, which caused a decrease in cell capacity. The final products on discharge included Na2Sn with 1< n < 3, which differed from Na2S3 found in traditional Na-S battery. Reduction of sulfur in the mixed cathode led to an increase in overall energy density over ZEBRA batteries. Despite of the initial drop in cell capacity, the mixed cathode demonstrated relatively stable cycling with more than 95% of capacity retained over 60 cycles under 10mA/cm2. Optimization of the cathode may lead to further improvements in battery performance.

Lu, Xiaochuan↗
DOE OSTI2012

Cassettes for solid-oxide fuel cell stacks and methods of making the same

Solid-oxide fuel cell (SOFC) stack assembly designs are consistently investigated to develop an assembly that provides optimal performance, and durability, within desired cost parameters. A new design includes a repeat unit having a SOFC cassette and being characterized by a three-component construct. The three components include an oxidation-resistant, metal window frame hermetically joined to an electrolyte layer of a multi-layer, anode-supported ceramic cell and a pre-cassette including a separator plate having a plurality of vias that provide electrical contact between an anode-side collector within the pre-cassette and a cathode-side current collector of an adjacent cell. The third component is a cathode-side seal, which includes a standoff that supports a cathode channel spacing between each of the cassettes in a stack. Cassettes are formed by joining the pre-cassette and the window frame.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2012

Optimized cell configurations for stable LSCF-based solid oxide fuel cells

Lanthanum strontium cobalt iron oxides (La(1-x)SrxCoyFe1-yO3-f; (LSCF) have excellent power density (>500 mW/cm2 at 750.degree. C.). When covered with a metallization layer, LSCF cathodes have demonstrated increased durability and stability. Other modifications, such as the thickening of the cathode, the preparation of the device by utilizing a firing temperature in a designated range, and the use of a pore former paste having designated characteristics and combinations of these features provide a device with enhanced capabilities.

25 ENERGY STORAGE↗
DOE OSTI2012

Demonstration of a Highly Efficient Solid Oxide Fuel Cell Power System Using Adiabatic Steam Reforming and Anode Gas Recirculation

Solid oxide fuel cells (SOFC) are currently being developed for a wide variety of applications because of their high efficiency at multiple power levels. Applications for SOFCs encompass a large range of power levels including 1-2 kW residential combined heat and power applications, 100-250 kW sized systems for distributed generation and grid extension, and MW-scale power plants utilizing coal. This paper reports on the development of a highly efficient, small-scale SOFC power system operating on methane. The system uses adiabatic steam reforming of methane and anode gas recirculation to achieve high net electrical efficiency. The anode exit gas is recirculated and all of the heat and water required for the endothermic reforming reaction are provided by the anode gas emerging from the SOFC stack. Although the single-pass fuel utilization is only about 55%, because of the anode gas recirculation the overall fuel utilization is up to 93%. The demonstrated system achieved gross power output of 1650 to 2150 watts with a maximum net LHV efficiency of 56.7% at 1720 watts. Overall system efficiency could be further improved to over 60% with use of properly sized blowers.

01 COAL, LIGNITE, AND PEAT↗