Researchers achieved 1,270 Wh/L in an anode-free lithium metal battery

This is only relevant for those deeply involved in fundamental or early-stage battery research.

An energy density of 1270 Wh/L is indeed roughly double what is currently found in top-tier electric vehicles. However, as with many battery research avenues, it is not viable on a practical level unless a major breakthrough is discovered in addition.

Here is a list of all the issues that must be resolved before such battery technology is viable for commercial use.

It only lasts about 100 charge cycles before degrading to 80% capacity, which is not sufficient for commercial use. LiFePO4 reaches this after a minimum of 3000 cycles.

It uses silver. In addition to this likely being a deal-breaker for mass production, the paper probably downplays the mass loading of silver required to maintain that 99.6% efficiency.

Anode-free batteries have zero excess lithium. Every time you charge/discharge, you lose a tiny fraction of lithium to side reactions. The paper claims a Coulombic Efficiency of 99.6%. The fact that they hit ~82% suggests the degradation is severe and inevitable without a massive reservoir of extra lithium, which defeats the "energy density" gain.

Density suppression for 100 cycles is not proof of safety. Dendrites often grow slowly and trigger short circuits later in life (cycle 200+).

There is also the known problem with pouch cells and significant volume change ("breathing"). The paper quotes volumetric density including packaging, but does it account for the swelling that happens after 50 cycles? Often, these cells puff up like balloons, rendering them unusable in a tight battery pack.

They tested at 0.5C (2-hour charge). Fast charging (15-20 mins) typically destroys lithium metal anodes instantly by causing rapid dendrite growth. This technology is likely limited to slow-charging applications.

Finally, there is no mention of temperature effects on performance.

I don’t mean to be negative, and research like this is extremely important. But this research paper is not properly framed. It’s like an archaeologist finding a buried house and extrapolating that this could mean we found an entire city! Why can’t we just say that the archaeologist found an interesting house?

If all four of the battery breakthrough articles on that page actually worked in a product, battery performance would be far higher than it is now. It seems to be possible to trade off charging rate, Wh/L, Wh/Kg, number of cycles, and safety. Any article that doesn't give all the stats is deceptive.

It's progress. The trouble is reading about it through the hype department at the university's PR operation.

For comparison gasoline has about 9000 Wh/L of raw chemical energy, of which maybe 30-40% gets converted to useful work.

> the battery retained 81.9% of its initial capacity after 100 cycles

That's really terrible.

It's interesting, but 20% loss after 100 cycles is just not great. NMC gets that at near 1000 cycles. LFP gets that at near 5000 cycles.

Can the liquid be agitated to avoid dendrite growth?

That’s fine but it’s only for the first bunch of cycles, after that it’s way worse than standard lion batteries.