In Situ NMR Probe for Coin Cell Batteries

This in situ nuclear magnetic resonance (NMR) probe takes NMR spectroscopy’s ability to noninvasively observe real-time chemical changes with high resolution and carries it over to real, functional battery cells. Watch now to see how the probe enables the chemical analysis of realistic battery cells by powerful high-field NMR methods for the first time.

Transcript

00:00:00 [Music] this is a coin cell battery much of the type that powers many of your household appliances now the fundamentals of this chemistry are fairly well known but if you want to squeeze every last little bit of performance from this battery the devil is in the chemical details now how do we find out about these

00:00:32 details that's where this big guy comes in this is an nmr magnet and if we were to put this coin cell in the magnet and found a way to apply an oscillating radio frequency magnetic field to the material inside the coin cell the atomic nuclei inside would just sing

00:00:52 about their chemical environments information we really really want to know if we're optimizing performance problem the metal casings of the cell metal casings are well known to block oscillating radio frequency magnetic fields so for a long time it was thought that nmr of coin cells would be an

00:01:13 extraordinarily difficult task so how do we do this well that's where this guy comes in this is our nmr probe designed to deliver oscillating magnetic fields to the inside of the coin cell i so happen to have a coin cell already loaded in the coil

00:01:37 this coil produces an oscillating radio frequency magnetic field and what we found is that if you lay the coin cell in to the coil just right oscillating magnetic fields are actually able to squeeze through the polymer gap between the two metal casing and as a result the nmr experiment works and we get the chemical information we

00:01:57 wish to see so we have loaded a coin cell into the nmr probe and we are currently running an nmr experiment on the coin self the probe base is right here it's been the probe has been inserted into the bore into a very large superconducting magnet which provides the static magnetic field for the experiment

00:02:17 this black cable is a connection to the nmr spectrometer which provides the pulses that stimulate the nuclei in the coin cell as well as record signals coming off of the coin cell for detection finally i'd like to point out that this white cable right here contains direct current leads which connect to the battery and go over to a

00:02:40 potentiostat and at the potentiostat we're able to drive the coin cell using whichever electrochemical experiment we wish to perform because conventional wisdom said that oscillating magnetic fields could not be delivered to the inside of the battery on account of metal casings researchers had developed this paradigm where

00:03:02 the battery was adapted for the nmr probes that were available and so this involved creating custom cells that used very thin wires to deliver the current it was like plastic casings and it changed the internal constituency of the battery cell so that it was really a question of whether or not

00:03:24 the chemistry and the details that were being observed actually carried over to a real functional cell the first time i began working with this probe i had loaded a test cell into the probe and when i started seeing the nmr signals that were coming through i thought something must be wrong these signals

00:03:41 have to be artifacts these are way too clean way too strong for this to actually be relaying information about the chemical environments but didn't take long to realize that sure enough the signals that we were measuring actually corresponded to the lithium environments we expected in the tests so everybody is interested in batteries that last longer deliver more power and

00:04:02 are all around cooler and that really is just the fundamental driving force for this work we are using this technology to study cutting edge next generation battery chemistries that will be used in grid storage and electric vehicles