ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Impedance studies of nickel/cadmium and nickel/hydrogen cells using the cell case as a reference electrode (1990)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Impedance measurements have been made on several Ni/Cd and Ni/H2 flight-weight cells using the case as a reference electrode. For these measurements, the voltage of the case with respect to the anode or cathode is unimportant provided that it remains stable during the measurement of the impedance. In the cells measured so far, the voltage of the cell cases with respect to the individual electrodes differ from cell to cell, even at the same overall cell voltage, but they remain stable with time. The measurements can thus be used to separate the cell impedance into the contributions of each electrode, allowing improved diagnosis of cell problems.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Journal of Power Sources (ISSN 0378-7753); 29; 467-476
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Impedance studies of Ni/Cd and Ni/H cells using the cell case as reference electrode (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Many impedance studies were carried out on Ni electrodes and Ni/Cd and Ni/H batteries. In order for impedance to become a diagnostic tool, accurate and reproducible measurements must be made, and some way of separating the contributions of the individual electrodes must be found. Using the PAR and the Solartron impedance equipment, studies have found that consistent measurements can be made if the cells or electrodes are equilibrated at the voltage of interest. In the charged state, equilibration times required are short, on the order of a few hours or less, but the equilibration time required becomes progessively longer as the voltage is lowered. The cell case can be used as a reference electrode during impedance measurements. The voltage of the case with respect to the electrodes is unimportant provided that it does not change appreciably during the course of the measurement. Measurements were made with several uncycled Ni/Cd cells, one from a lot which was known to have faulty Cd electrodes and another from a lot which showed excellent cycle life and presumably had good Cd electrodes. The impedances of the Ni electrodes vs. the case were similar, while the impedance of the poor Cd electrodes vs. the case. A 50 AH Ni/H cell was also investigated. After subtraction of the ohmic resistances, the sums of the impedances of the individual electrodes were very close to the impedance of the total cell. This indicates that the method is valid for examining the characteristics of the individual electrodes in situ.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: Space Electrochemical Research and Technology Conference: Abstracts; p 29
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Impedance studies of Ni/Cd and Ni/H2 cells using the cell case as a reference electrode (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Impedance measurements have been made on several Ni/Cd and Ni/H2 flightweight cells using the case as a reference electrode. For these measurements the voltage of the case with respect to the anode or cathode is unimportant provided that it remains stable during the measurement of the impedance. In the cells measured so far, the voltages of the cell cases with respect to the individual electrodes differ from cell to cell even at the same overall cell voltage, but they remains stable with time. The measurements can thus be used to separate the cell impedance into the contributions of each electrode, allowing improved diagnosis of cell problems.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Electrochemical Research and Technology (SERT), 1989; p 197-209
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    I-BIEM, an iterative boundary integral equation method for computer solutions of current distribution problems with complex boundaries: A new algorithm. I - Theoretical (1988)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A new algorithm for an iterative computation of solutions of Laplace's or Poisson's equations in two dimensions, using Green's second identity, is presented. This algorithm converges strongly and geometrically and can be applied to curved, irregular, or moving boundaries with nonlinear and/or discontinuous boundary conditions. It has been implemented in Pascal on a number of micro- and minicomputers and applied to several geometries. Cases with known analytic solutions have been tested. Convergence to within 0.1 percent to 0.01 percent of the theoretical values are obtained in a few minutes on a microcomputer.
    Keywords: COMPUTER PROGRAMMING AND SOFTWARE
    Type: Electrochemical Society, Journal (ISSN 0013-4651); 135; 285-293
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    Impedances of nickel electrodes cycled in various KOH concentrations (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Recent tests at Hughes have shown that Ni/H2 cells cycled in 26 percent KOH have much longer lives than those cycled in other concentrations. As part of an ongoing program to try to correlate the impedances of nickel electrodes with their life and performance, impedances were measured of a number of electrodes from these tests that had been cycled in concentrations from 21 to 36 percent KOH. These had ranged from about 1000 to 40,000 cycles. After cycling ten times to reduce possible changes due to storage, impedances were measured at five voltages corresponding to low states of charge. The results were analyzed using a standard circuit model including Warburg impedance term. Lower kinetic resistances and Warburg slopes were found for several electrodes which had been cycled in 26 percent KOH even though they had been cycled for a much longer time than the others. Interpretation of the data is complicated by the fact that the cycle lives, storage times, and failure mechanisms varied. Several other circuit models have also been examined, but the best correlations with life were found with parameters obtained from the simple model.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Electrochemical Research and Technology; p 89-100
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Impedance measurements on a spiral-wound nickel/metal hydride cell cycled in a simulated Leo orbit (1993)
    In:  CASI
    Details
    Publication Date: 2016-05-14
    Description: A spiral-wound size C cell was cycled at 25 C in a low earth orbit (LEO) regime at 50 percent depth of discharge (DOD) with approximately five percent over-charge. The nominal capacity was 3.5 AH. The cell was cycled for 2000 cycles. Capacity checks and impedance measurements over the complete range of state of charge were made upon receipt and after 500, 1000, and 2000 cycles. The capacity of the cell was essentially unchanged until after the impedance measurements at 2000 cycles. Only small changes in the impedance parameters were observed, but there was somewhat more scatter in the data after 2000 cycles. When the cell was returned to LEO cycling after 2000 cycles, only 38 percent of the capacity could be obtained. It is believed that the cell failed because of an equipment failure at the end of the final impedance measurements which allowed an over-discharge.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Electrochemical Research and Technology; p 97-108
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Characterization of cobalt-dipped nickel electrodes with fibrex substrates (1995)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Nickel electrodes using fibrous substrates have poorer initial utilization of the active material than those using conventional nickel sinter substrates. Previous investigators had shown that utilization can be dramatically improved by dipping these electrodes in a cobalt solution immediately after the electrochemical impregnation, before formation and cycling is carried out. The present study looked at the gas evolution behavior of dipped and undipped electrodes, impedance curves, and the charge-discharge curves to try to understand the reasons for the improvement in utilization. Impedance measurements under open circuit conditions indicate that some of the improvement is due to a reduction in the ohmic resistance of the surface layer of the particles, in agreement with earlier work. The charge-discharge curves suggest that there may also be an additional increase in the ohmic resistance of the surface layer of the undipped electrode during charging.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: NASA-TM-106969 , E-9726 , NAS 1.15:106969
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Raman spectral observation of a new phase observed in nickel electrodes cycled to failure (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A new phase is reported in nickel electrodes from Ni/H2 boilerplate cells which were cycled to failure in electrolyte of variable KOH concentration (21 to 36 percent). Raman spectra clearly show the presence of this phase, and these spectra have been used to estimate the amounts present on these electrodes. Ten of 12 electrodes examined contain this new phase. The cycle life at higher KOH concentrations (31 and 36 percent) was greatly reduced, and nickel electrodes from these cells exhibited extensive amounts of this new phase. The presence of this new phase correlates with cell failure defined by low end of discharge voltages. It is proposed that the lowered capacity and failure of these electrodes was caused by loss of active mass and formation of a phase with reduced electrochemical activity. These results indicate that formation of the new phase is accelerated at higher KOH concentrations.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Space Electrochemical Research and Technology; p 81-87
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    Impedances of Li/SO2 cells retrieved from the Long Duration Exposure Facility (LDEF satellite) and comparison with cells stored terrestrially (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Impedances were measured on several Li/SO2 cells retrieved from the Long Duration Exposure Facility (LDEF) satellite. These cells were used to power instruments and recorders and had all been partially or fully discharged. Impedances were also measured on several cells that were stored in cold storage since manufacture. Unfortunately, none of the cells stored terrestrially had undergone any discharge, whereas all of the cells on the satellite were at least partially discharged early in the mission and then remained on orbit for about 5 years further. It has been observed by others that storage of an Li/SO2 cell after partial discharge, increases the resistance and thickness of the passive film on the Li electrode, as indicated by an increase in the time for recovery of voltage when a load is applied (voltage lag), or in some cases by an inability of a cell to sustain a normal current after such storage. Since the cells stored terrestrially were not discharged in the same manner as the LDEF cells, a direct comparison cannot be made. Thus, the effects of the space environment cannot be separated from the effects of storage after partial discharge. It is believed that the increases in impedance in the LDEF cells are largely due to the storage upon partial discharge rather than the effects of the space environment.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-TM-104526 , E-6400 , NAS 1.15:104526
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Impedances of electrochemically impregnated nickel electrodes as functions of potential, KOH concentration, and impregnation method (1989)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Impedances of fifteen electrodes form each of the four U.S. manufactures were measured at 0.200 V vs. the Hg/HgO reference electrode. This corresponds to a voltage of 1.145 for a Ni/H2 cell. Measurements were also made of a representative sample of these at 0.44 V. At the higher voltage, the impedances were small and very similar, but at the lower voltage there were major differences between manufacturers. Electrodes from the same manufacturers showed only small differences. The impedances of electrodes from two manufacturers were considerably different in 26 percent KOH from those in 31 percent KOH. These preliminary results seen to correlate with the limited data from earlier life testing of cells from these manufacturers. The impedances of cells being tested for Space Station Freedom are being followed, and more impendance measurements of electrodes are being performed as functions of manufacturer, voltage, electrolyte concentration, and cycle history in hopes of finding better correlations of impedance with life.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-TM-103283 , E-5738 , NAS 1.15:103283 , International Symposium on Electrochemical Impedance Spectroscopy; May 22, 1989 - May 26, 1989; Bombannes; France
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...