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Tesla researchers show path to next-gen battery cell with breakthrough energy density

Tesla’s battery research group in Canada released a new paper that shows a path to a next-generation battery cell with breakthrough energy density.

There are some hurdles to figure out, but the new research identifies the bottlenecks in points to potential solutions.

Jeff Dahn and his team in Canada have long been conducting leading battery research, and for the last four years, they have been doing it in partnership with Tesla.

They have been focused on improving on the current generation of Li-ion battery cells, but they have also been looking at the possible next generation of battery cells that don’t just offer incremental improvements but breakthrough performance.

A lot of people believe that this next-gen battery is going to be solid-state batteries, but Tesla and Dahn’s research group have suggested a different path with “anode-free lithium-metal pouch cells with a dual-salt LiDFOB/LiBF4 liquid electrolyte.”

In a research paper published last year, they described new battery cells with higher-energy density that don’t require an expensive new method of manufacturing.

It offered a clear path to producing batteries with more energy without increasing cost, but they still had to figure out the longevity.

At the time, they were only able to achieve 90 cycles, which are not enough for virtually all commercial applications — certainly not good enough for electric cars.

Now Dahn and his team published a new paper financed by Tesla and co-authored by four Tesla employees.

In the new paper, called “Diagnosing and correcting anode-free cell failure via electrolyte and morphological analysis” and published in the prestigious scientific journal Nature, they identify the problems with longevity and introduce a solution.

They wrote in the abstract:

Recently, we demonstrated long-lifetime anode-free cells using a dual-salt carbonate electrolyte. Here we characterize the degradation of anode-free cells with this lean (2.6 g Ah−1) liquid electrolyte. We observe deterioration of the pristine lithium morphology using scanning electron microscopy and X-ray tomography, and diagnose the cause as electrolyte degradation and depletion using nuclear magnetic resonance spectroscopy and ultrasonic transmission mapping. For the safety characterization tests, we measure the cell temperature during nail penetration.

They found that with their dual-salt electrolyte there’s an inactive matrix in-situ of dead lithium that forms large, dense lithium columns inside — forming an ideal lithium morphology:

The paper shows that they not only identify the bottlenecks, but it also introduces a solution by optimizing the electrolyte to improve the life of the lithium-metal anode-free cells to 200 cycles, which is a massive improvement over less than a year.

Electrek’s Take

Obviously, 200 cycles is still not good enough for commercialization, but this new paper shows that the researchers now understand how the cell deteriorates, and they are already finding solutions to fix the deterioration.

If it keeps improving at this pace, it could relatively soon be used in Tesla’s vehicles and the paper shows the potential impact:

They could greatly increase the efficiency, resulting in either more range with the same battery pack size or lower weight and lower cost for the same range, which Tesla has hinted as being the goal recently.

With that kind of improvement in energy density, you can see why Dahn’s team can see this new cell as the potential “next-generation” of batteries.

We are talking about a big enough breakthrough that it could enable electric planes. It’s exciting stuff and definitely something to keep an eye on.

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