As a point of reference, Google says that somewhere between 500-2000 cycles you can expect a regular lithium battery to degrade to 80%. So this is worse, but in the ballpark. Seems reasonable for a research prototype to be a little worse than a commercial product that’s had years to become highly optimized.

But depending on cost, in my hopeful optimistic universe, that could mean bringing back replaceable batteries.

Much more stable chemistry. In stationary applications, like UPS systems and off grid electrical systems, lead acid is still the standard, due to having stable chemistry, very unlikely to catch fire, and a cost to capacity ratio that is still very good.

The degradation seems pretty bad, but if it's stable from 300 cycles onwards, you could take 75% as the actual capacity of the battery.

Boats, planes, drones, phones, bikes... Anywhere that you can maximize storage cell capacity in odd shaped volumes and spaces/designs. It's great.

Having looked at comparative data, it's not really out of the norm...

One of the fabricated battery pouch cells was even able to work after being folded and cut off. “That proves its high safety for practical application,” the researchers emphasized.

If you can cut it in half and it still works I doubt piercing it will do much.