Without a satisfactory energy density, this battery tech will go nowhere. Every single article about this new Al-Ion battery leaves out a comparison of energy density between this new tech and typical Li-Ion. I have a strong suspicion that the reason is its energy density is terrible and no reasonable amount of improvement to the cathode could possibly bring it up to Li-Ion density while still being comparably cheap or easy to manufacture.

So what is te problem with the voltage being on the low side? Can't they just being wired (more) in series to overcome this?

You're right Joel, I've read their paper and the energy density is a meager 40 Wh/kg which is 3 to 4 times less than any Li-ion battery.
Also, they couldn"t compete with lithium's voltage because the reduction potential of the reaction Al+ + 3 e- = Al at the cathode is 1.7V against the reaction Li+ + e- = Li, which has a reduction potential of 3.04 V. This means that the maximum voltage is two times lower than lithium-ion.
Finally, they use a ionic liquid which is expensive and most are quite toxic.

With the development of a better cathode the voltage drop can be perhaps solved. The energy density from Al is not this height. So what, but look at the persons who have developed the device and from where the are originally. Only one American is in the group of 7. What is going on? This bothers my more.

A quick charging battery is only half the solution since you would also need a battery charger and connection that could handle the current and dissipate the heat. A low density battery will only be useful if it is very large and cheap. The promise of an aluminum battery has been around for years but handling the byproducts or keeping the battery from poisoning itself has been a problem. If the claim holds up, one that could be recharged this many times would be a breakthrough.

Jeeez, sounds like everything other than L-ion falls incredibly short in one or more critical areas. Why don't we just connect a row of potatoes to an electric motor...

I think that is neat. With lower cost and less chance for fire and being bendable, I can see a future for this battery.

I am thankful that none of the most regular negative, nothing-will-ever-work-and-that-is-a-stupid-idea guys is in charge of research and development anywhere!

If its cost can be made advantageous there are plenty of stationary applications for energy storage where it's advantages could far outweigh its disadvantages. You may not see one in your phone but in sheds in every town and city instead. In the Midwest for example the cornfield at the edge of every small town would provide ideal land use for distributed storage.

I think home solar off grid or grid tied systems would welcome such a battery.