Multinuclear nmr study of Lithiated Silver Vanadium Oxide By Christina Zayas, Aquinas High School

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

Introduction: Goal 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.

A Lithiated Silver Vanadium Oxide Model

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.

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.

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.

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.

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.

Why do we need better batteries?

• To power things like:

The Challenge

• To create secondary batteries that are the following:

• Higher in energy
• Have a longer life span
• Are convenient to use
• Are durable

Secondary Batteries

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.

Experiment -continued

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.

Pictures of the Hunter NMR Lab