Researchers over at Lawrence Berkeley National Laboratory have made a new lithium-ion battery discovery that could prove a little disconcerting to a lot of folks in the energy storage field. The finding comes out of a first-of-its-kind analysis using X-ray absorption spectroscopy, and apparently it contradicts “numerous” studies aimed at improving the efficiency of lithium-ion batteries.
The good news is, the new lithium-ion battery discovery could accelerate the development of next-generation EV batteries, so let’s see what all the buzz is about.
Interpretation of x-ray absorption spectra analysis (courtesy of Berkeley Lab).
The New Lithium-Ion Battery Discovery
The new lithium-ion battery research focused on unlocking some of the mystery behind the nanoscale function of the liquid electrolyte in lithium-ion batteries. For those of you new to the battery topic, the electrolyte is the stuff that enables an electrical charge to flow from the battery to whatever device you want to electrify, so yeah, the electrolyte is pretty important.
The electrolyte commonly used in lithium-ion batteries consists of a lithium salt dissolved in a solvent, typically based on an alkyl carbonate. Here’s the deal according to study co-author Richard SayKally of Berkeley Lab:
There’s disagreement in the battery industry on the nature of the local solvation environment of lithium ions in these solutions, a critical issue because the desolvation of the ions as they move through the negative electrode is believed to limit the electrical power that can be made available.
Until now, computer modeling has predicted that the solvation structure for the lithium ion is based mainly on tetrahedral coordination (a tetrahedron is a 3-D form made of four triangular faces) (and solvation is fancyspeak for the behavior of molecules in a solvent).
The Berkeley team found something quite different, and they used a quite different method to get there.
The team developed a new device that shoots a nanoscale “liquid beam” into a vacuum chamber, where it crosses an X-ray beam. To get the X-ray beam, they checked into beamline 8.0.1 of Berkeley Lab’s Advanced Light Source facility, which produces X-ray beams for X-ray spectroscopy.
That was the easy part, relatively speaking. The next step was to get hold of a supercomputer or two over at the National Energy Research Scientific Computing Center and decipher the results of the spectroscopy.
The team found that, in contrast to the solvation number of 2 or 3 characteristic of tetrahedral coordination, the lithium ion in the electrolyte had a solvation number of 4.5.
So, in order to develop more efficient electrolytes, foundational research into next-generation lithium-ion batteries needs to get over its focus on modeling based on tetrahedral coordination.
In other words, don’t hold your breath for a new super-efficient electrolyte to hit the commercial market any time soon, but the way forward is a lot more clear now.
What About Fuel Cells?
Okay, so much for the new lithium-ion battery discovery. If you’ve been checking out the horse race between Li-ion batteries and fuel cells for domination of the electric vehicle market, the new Berkeley discovery bumps things up a notch in favor of batteries.
That’s good news for Tesla and any other auto manufacturer that has committed exclusively to battery EV technology.
On the other hand, the Saykally Group at Berkeley Lab is also responsible for a discovery that could help blow the fuel cell market wide open, at least in terms of finding a more sustainable source for hydrogen fuel.
That study, published in 2007, used a “microjet” of fluid concept similar to the methodology deployed for the new lithium-ion battery study. The Saykally team found that you can generate hydrogen gas and an electrical current, too, by forcing a fluid through nanoscale conduits.
The last time we checked, the process was patented (#8372374 for those of you keeping score at home) and is available for further research or licensing.
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