Electrochemical cells for energy harvesting
a technology of electrochemical cells and capacitors, applied in the direction of electrochemical generators, aqueous electrolyte fuel cells, cell components, etc., can solve the problems of reducing the voltage of the cell (and power loss) over time, and only being used in specific conditions, so as to reduce the oxygen content.
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
Problems solved by technology
Method used
Image
Examples
example 1
[0049] Cell performance vs atmosphere and acidity of electrolyte—For this example, all positive electrodes were RuO2.˜0.5H2O on Pt foil and the negative electrodes were made from Pt foil, but the electrodes were tested under different atmospheres and using different concentrations of sulfuric acid. The results for Example 1 are shown in FIGS. 3, 4, and 5.
[0050] The RuO2.˜0.5H2O was prepared by heating as-received RuO2.2H2O (Alfa Aesar) at 150° C. for 18 hours in air. Pt foil (0.1 mm thick, Alfa Aesar) was cut into strips and cleaned in reagent-grade aqua regia. Positive electrodes were prepared by adding a drop of a 5% Nafion ionomer solution (Ion Power, Inc.) to the surface of the Pt foil, and then pressing 1 to 3 mg of the ground hydrous RuO2 on the Nafion-coated Pt foil at 1200-2000 psi for 30 s. The positive electrodes were assembled as full cells in stacked structures with a trilayer material of polypropylene-polyethylene-polypropylene (Celgard 2300) serving as the separator a...
example 2
[0057] Dependence of cells on hydrogen pressure—The cell in FIG. 5 was compositionally identical to those in FIG. 3, but it was tested in cells were evaluated under a range of low hydrogen pressures to verify that dilute hydrogen is the energy source for the devices. Cells were constructed with positive electrodes of RuO2.0.5H2O on Pt and negative electrodes of Pt black on Pt and were submerged in 0.1 M H2SO4 at 20° C. Laboratory-grade oxygen and nitrogen were mixed in a ratio of 1 to 5 (to mimic atmospheric conditions) and then 2000-8000 ppm of hydrogen gas was added to the flow. The current density was measured when the cell was under a 100 mV load and plotted vs. the hydrogen concentration in FIG. 6. The cell performance was proportional to the fixed hydrogen concentration of the atmosphere. Although there is 0.5 to 1 ppm of H2 naturally found in the atmosphere, this has a negligible effect on the 2000-8000 ppm of added H2. The linear regression of the line to 1 ppm indicates tha...
example 3
[0058] High temperature operation of cell and fuel cell mode—A cell was made using RuO2.0.5H2O on Ti as the positive electrode and TiO2 on Ti as the negative electrode in 0.1 M H2SO4 at 25° C. FIG. 7 shows a portion of the measured cell voltage as a function of time as the cells were discharged at 5 μA. Cycles 278-280 are shown in FIG. 7A and cycle 278 is expanded in FIG. 7B. The cells took 170 s to discharge and 2 h were allowed for recharging. From this data, the cell capacity was 0.2 μh / cm2, and the mean power (half of max) was 0.45 μW / cm2. The cell was run for a total of 800 h and 356 cycles.
[0059]FIG. 8 shows the measured current for the cell in FIG. 7 as it was heated from room temperature to 60° C., as it was operated in steady-state or fuel cell mode (the voltage of the cell remains constant while the current is drained, and the cell is not discharged). The cell current increased from 0.09 μA / cm2 at 22° C. to nearly 2.0 μA / cm2 at 56° C. The increase in the cell with increas...
PUM
Login to View More Abstract
Description
Claims
Application Information
Login to View More