Aluminum is a very interesting material: very light and having 3 free electrons. Air is the other magic material: Not necessary to have it on board!
But this Aluminum device is between a battery (that needs being electrically recharged) and a fuel cell that needs a change of material. For me, it is closer to a FC.
This is justifying the need for a lithium battery to start and manage the process.
Probably an interesting device if no permanent oxidization of aluminum: thus no contact with air. Air electrodes are a dream for a long time but technology is hard to improve (limited life time because of electrolyte percolation).