Multinuclear NMR Study of Lithiated Silver Vanadium Oxide

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Multinuclear NMR Study of Lithiated Silver
Vanadium Oxide

• By Christina Zayas, Aquinas High School
• Mentors
• Ms. Nicole Leifer, CUNY Doctoral Student
• Dr. Steve Greenbaum, Professor of Physics at
  Hunter College

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IntroductionGoal of Experiment

• To test the hypothesis that the Ag ions are
  reduced during the beginning stages of lithiation
  before V4 at higher lithium content.
• The ability to determine which undergoes
  reduction first will enable us to determine what
  actually happens at a microscopic level.
• Ag0 is an excellent conductor. Therefore, the
  ability to reduce Ag 2 1 to Ag 0 first will
  allow increased electric conductivity, which
  would result in longer lasting primary and
  secondary batteries.

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A Lithiated Silver Vanadium Oxide Model
LiAsF6
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What is NMR Spectroscopy?

• Nuclear Magnetic Resonance (NMR) is a phenomenon
  that occurs when the nuclei of certain atoms are
  immersed in a static magnetic field and exposed
  to a second magnetic field.
• Spectroscopy is the study of the interaction of
  electromagnetic radiation with matter.

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NMR Spectroscopy

• NMR Spectroscopy is the use of the NMR phenomenon
  to study physical, chemical, and biological
  properties of matter.
• Studies are done by analyzing spectrums that are
  produced through NMR.

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NMR and Spin

• NMR only happens with nuclei with spin.
• Spin is a fundamental property of all unpaired
  electrons, protons, and neutrons.
• In NMR, there is only a concern for the unpaired
  spin of the nuclei (no electrons)
• NMR can only be performed on isotopes whose
  natural abundance is high enough to be detected.

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What is Spin?

• Protons will have a spin that is similar to a
  magnetic moment vector, causing the proton to
  behave like a tiny magnet with a north and south
  pole.
• When the proton is placed in an external magnetic
  field, the spin vector of the particle aligns
  itself with the external field, just like a
  magnet would.

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How can NMR help to create better batteries?

• NMR spectrum is sensitive to a number of physical
  parameters that are directly related to the
  efficacy of the working cell.
• Li-ion mobility, electronic conductivity, and
  changes in the valence or electronic structures
  of the cations that are involved in the redox
  processes
• It is element-specific and may be use to directly
  examine the species that are involved in the
  working battery.

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Why do we need better batteries?

• To power things like

Pacemakers
Hearing Aids
Rechargeable Cars
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The Challenge

• To create secondary batteries that are the
  following
• Higher in energy
• Have a longer life span
• Are convenient to use
• Are durable

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Secondary Batteries
Nickel Cadmium Battery
Lead Acid Battery
Lithium Battery
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Experiment

• This graph indicates that vanadium has an
  oxidation state of 4 at this level of lithium.
• It is paramagnetic and parabroading at this
  level.
• The electron configuration is 1s22s22p63s23p64s1,
  which means that it has only one electron and it
  is paramagnetic.

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Experiment -continued

• In Figures 2 and 3, the lithium levels are
  decreased and as a result V4 does not occur.
• It is not paramagnetic.

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Conclusion

• It has been concluded so far that lithiated
  silver vanadium oxide could be useful to create
  better secondary batteries.
• Further research is needed to determine its
  usefulness under all conditions.
• This has been a delay in our lab because some of
  the machines were broken.

NMR Magnet
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Pictures of the Hunter NMR Lab