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Principles of R adioactive T racing M ethod

Principles of R adioactive T racing M ethod.

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Principles of R adioactive T racing M ethod

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  1. Principles of Radioactive Tracing Method The radioactive tracing method is based on replacing in the electrolyte some of the 32S ions by the 35S isotope (betta-emitter). Then the plates are dipped into the new electrolyte and polarized. They are extracted from the cell and the distribution of the “heavy” PbSO4 throughout the plates is analyzed. This is possible by special betta-radiation detectors. The method provides an unique tool to investigate the processes related to the electrolyte stratification effect during operation of LAB. Source: Fl. Mattera, Etude des Modes de Vieillissement des Accumulateurs au Pb Utilises dans les Systemes Photovoltaiques, PhD thesis, 29 Octobre 1999, Institut National Polytechnique de Grenoble, France.

  2. e- 35S sample b scanner polymer screen with BaFBrEu2+ F + e- (BaFBr -) Eu2+ + b Eu3+ BaFBr - + photon BaFBr + e- (Eu2+) + photon He-Ne laser, 10 mW detector Principles of Radioactive Tracing • electrolyte stratification during operation of LAB. • distribution of PbSO4 across the battery plates. • some of the 32S atoms are replaced by 35S isotope (a b-emitter). • the electrolyte contains some “heavy”H2SO4. • the distribution of 35S - traced by b-radiation detectors. Source: Fl. Mattera, Etude des Modes de Vieillissement des Accumulateurs au Pb Utilises dans les Systemes Photovoltaiques, PhD thesis, 29 Octobre 1999, Institut National Polytechnique de Grenoble, France.

  3. After the first discharge After the first recharge • the plate is dipped in the electrolyte, • discharged, • recharged again. Image of one side of a positive electrode Source:F. Mattera, D. Desmettre, J. Martin, Ph. Malbranche, J. Power Sources, 113 (2003) 400-407.

  4. Intensity scale Influence of cycle number on sulphation charged positive plate after: 2 cycles 20 cycles 20 cycles, washed 40 cycles, washed substantially higher content of PbSO4 in the bottom part of the plates than in the upper one (batteries with electrolyte stratification). Source: Fl. Mattera, Etude des Modes de Vieillissement des Accumulateurs au Pb Utilises dans les Systemes Photovoltaiques, PhD thesis, 29 Octobre 1999, Institut National Polytechnique de Grenoble, France.

  5. Softening and shedding of PAM • charged positive plate after 40 cycles. • The plate is rinsed with water. softened PbO2particles are eliminated from the surface by rinsing, some hard PAM around the grid bars, uneven PbSO4distribution. Source: Fl. Mattera, Etude des Modes de Vieillissement des Accumulateurs au Pb Utilises dans les Systemes Photovoltaiques, PhD thesis, 29 Octobre 1999, Institut National Polytechnique de Grenoble, France.

  6. Discharged positive plate: Before cycling After 40 cycles Softening and shedding of PAM more severe shedding of PAM in the bottom part of the plates Source: Fl. Mattera, Etude des Modes de Vieillissement des Accumulateurs au Pb Utilises dans les Systemes Photovoltaiques, PhD thesis, 29 Octobre 1999, Institut National Polytechnique de Grenoble, France.

  7. PAM grid Positive active mass degradation • charged positive plate after 40 cycles. • the plate is rinsed with water. Irreversible sulphation in the interface PAM/grid Source: Fl. Mattera, Etude des Modes de Vieillissement des Accumulateurs au Pb Utilises dans les Systemes Photovoltaiques, PhD thesis, 29 Octobre 1999, Institut National Polytechnique de Grenoble, France.

  8. GENERAL CONCLUSIONS: Major battery problems (solved or to be solved by: technological improvements, new materials or test/control procedures and devices) • Corrosion (open), grid expansion (solved). • Active material shedding (open). • Passivation (still a problem in some applications). • Sulphation, stratification (still a problem in some applications). • Antimony poisoning (solved). • Positive plates failure by Pb-Ca alloys (still a problem). • PCL 1 (solved). • PCL 2 (still a problem in some applications). • PCL 3 (solved). • Recombination problems, drying out (open). • TRAE (open). • Other problems??…. – you may add them as open or as solved!!!

  9. Acknowledgments • EC (specific program “Energy, Environment and Sustainable Development – Part B: Energy program”, contract No. NNE5/2002/18); • A. Kirchev, A. Gigova, M. Stoycheva, S. Vassilev and D. Pavlov for their contribution in the preparation of this course.

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