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 V 4+ at higher lithium content. The ability to determine which undergoes reduction first will enable us to determine what actually happens at a microscopic level. Ag 0 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 LiAsF 6

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: PacemakersHearing Aids Rechargeable Cars

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 Nickel Cadmium Battery Lead Acid Battery Lithium Battery

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 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1, which means that it has only one electron and it is paramagnetic.

Experiment -continued In Figures 2 and 3, the lithium levels are decreased and as a result V 4+ does not occur. It is not paramagnetic.

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

Pictures of the Hunter NMR Lab