Nevertheless, this is without doubt one of the most promising news about batteries ever published.
It was well known that an aluminum-sulfur battery could have very high performance, but previously nobody was able to make one that could be recharged without damage.
The point of this announcement is that at MIT they have discovered a molten salt electrolyte that not only allows recharge without damage, but it also allows the recharge at a very high current.
An aluminum electrode is among the best materials from the point of view of the ratio between electrical capacity and mass. It is worse than a lithium electrode only in the ratio 9/7.
However, in a lithium-ion battery, the electrode that stores lithium also contains other materials than lithium, so it is much heavier (and also much more expensive, because the other materials usually include nickel and/or cobalt). So an aluminum-sulfur battery should be both lighter and much cheaper.
This aluminum-sulfur battery will never be able to replace lithium batteries at small capacities, e.g. in a laptop or mobile phone, because it must be operated at a temperature high enough to melt the electrolyte, so it requires a thick thermal insulation, which would take too much of the device at small volumes.
On the other hand, at big capacities, such as for a car, it has extremely good chances of replacing the lithium-ion batteries.
The longevity of such a battery might be limited not by the number of recharge cycles, but by the time of operation, because the molten salt might slowly corrode whatever materials are used for making the battery. Nevertheless, there is a lot of experience with making enclosures and electrodes resistant to molten salts.
Moreover, this battery uses very low-temperature molten salts, which are heated only a little above the boiling temperature of water. Such a low temperature diminishes a lot the risks of corrosion and it allows the use of reduced thermal insulation.