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New Cobalt-Free Silicon EV Battery Is The Best Thing Ever (cleantechnica.com)

submitted 2 months ago* (last edited 2 months ago) by ArtikBanana@lemmy.dbzer0.com to c/technology@lemmy.world

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“This breakthrough development translates into a remarkable improvement in cell-core energy density, reaching 2,000Wh/L in batteries and approximately 1,700Wh/L in full-size EV batteries – more than double the performance of current state-of-the-art technologies,”

“Sienza’s 3D pure silicon anode has demonstrated an average gravimetric capacity of 2,941 mAh/g,” Professor Gharib said. “This means that for every gram of silicon, our batteries can store 2,941 milliampere-hours of electricity, significantly higher than the industry standard for graphite, with a gravimetric capacity of 372 mAh/g.”

Aside from completely avoiding the cobalt issue, Sienza notes that its manufacturing process does not rely on the solvent-based coating systems deployed for producing conventional lithium-ion batteries. Sienza cites one commonly used solvent in particular, N-methyl-pyrrolidone (NMP).

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[–] MagicShel@programming.dev 106 points 2 months ago* (last edited 2 months ago) (18 children)

That sounds really impressive. But describing it as "the best thing ever" really has my skepticism at full mast.

ETA: I can't find any mention of a single drawback or tradeoff to this new technology. That makes this a marketing piece rather than journalism. Nothing is ever better in every conceivable way than the current state of the art.

[–] Misspelledusernme@lemmy.world 21 points 2 months ago (5 children)

I'm doing a PhD in batteries. Not this issue specifically, but I hear a lot about different battery fields so I think I can speak on it.

The drawback is that the anode expands and contracts a lot during a cycle. This puts a lot of strain on the binder holding the film together, and on the contact between the film and the aluminum foil. This makes the battery degrade and fail after fewer cycles.

Below is an article in nature from 2020 where a group is trying to solve this issue by coating the Si platelet particles with carbon (adding complexity and mass). You can read about this issue on greater detail in the abstract and introduction. There are many articles tackling the same issue (many cited in this article), I just picked this one because it had info in the intro/abstract. Stable high-capacity and high-rate silicon-based lithium battery anodes upon two-dimensional covalent encapsulation

In addition, the expansion/contraction cycles causes the electrolyte to dry up. During the first few cycles of any battery, the electrolyte reacts with the electrodes to form passivating layers on the electrodes. When the particle contracts/expands excessively, the particle breaks apart and the passivating layer is ripped up. The passivating layer is then reformed, now on a larger area, which consumes more electrolyte. Eventually the cell fails from the lack of electrolyte.

Below is an article in nature from 2024 where a group tries to solve this issue by designing an electrolyte that creates a passivating layer that keeps its shape when the particle contracts, creating a shell. You can read more about the issue In the abstract, intro, and figures. High voltage electrolytes for lithium-ion batteries with micro-sized silicon anodes

These are solvable issues, but a lot of the solutions are either too complicated to scale up, or add too much mass/volume to make it worth it, or slow down the discharge rate. And any change anywhere, needs to be taken into account on the rest of the parts of the battery.

I don't know what Sienza Energy did. It's an MIT spin-off, so they probably know their stuff. All issues don't need to be solved for a battery to be functional, it just needs to be good enough. Any new battery factory "just" needs to find and scale-up the state-of-the-art components in the right combination. There will be a ton of drawbacks, but it will be better than the last battery factory.

[–] MagicShel@programming.dev 4 points 2 months ago (1 children)

I appreciate the information and the links. I didn't mean to imply this isn't exciting or useful technology, just that when an article is pure hype I come away thinking someone is trying to sell me something, not give me actual information.

[–] Misspelledusernme@lemmy.world 5 points 2 months ago

I feel the same way when I read these articles. They make it seem like everything is an earth shattering breakthrough when in reality, they're making a small (albeit worthwhile) contribution towards solving a problem that already has 20 other solutions with other trade-offs.

But I like it when I read about any new battery tech being scaled up do industrial scale, like the article here. That's the hard part.

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