mAh g-1 is very simple to understand. It is common notation to put a -1 exponent to indicate division.
Work to calculate the energy density comparison when that isn't even the point of the article. Everyone can look up the energey density and theoretical of a li-ion battery: 100-265 Wh/kg. There is absolutely no need to calculate anything.
Focus on the substance of the article. 60x faster charging rate as compared to Lithium-ion and make a comment regarding that. Otherwise your comments are as pointless as my reply to it.
Initially I responded with poor reading comprehension, so allow me an attempt at elucidation.
Elemental aluminum will react spontaneously, at room temperature, with water; liberating hydrogen gas. The reaction is exothermic generating a lot of heat. Both the hydrogen and heat can be used for energy. Heat for heating the home in winter and the hydrogen gas for fuel cells and accessory power.
The reaction needs nothing more than a reaction vessel to hold moderate pressure. A simple stainless vessel would work. The pressure being whatever you want to store your hydrogen at. More than likely, though, you would just go ahead and convert it to electricity with a fuel cell, in which case you don't need to store it.
Aluminum can be stored in blocks, outside. I envisage some northern resident walking outside on a brisk morning with a hack saw and removing a chunk of aluminum to throw in his 'furnace' (reaction vessel) to warm his house and charge his phone, etc. Afterwards you need to drain off the water and collect the alumina/aluminum hydroxide and toss it in the recycling bin.
Aluminum is basically free to store as energy. It requires no maintenance, no upkeep, doesn't degrade appreciably, easily transported. Hell you could build your house out of it. It's akin to wood.
Use cases: Remote residences in the winter. i.e. solar is garbage and no one is shipping you a nuclear reactor.
It's mentioned in the 2nd bullet point of the article link: 23.5MWh/m3
The benefit is you can store energy, in aluminum. It has a high energy density, you can safely store it anywhere, it requires no containment at all, etc.
Your last statement includes the answer to your own question. They are using the hydrogen, from water reacting with aluminum, to power a fuel cell.
How does your second statement have bearing on the article?
A quick search reveals no mention of CO2 Poisoning for hydrogen fuel-cells, but a majority mention of carbon monoxide poisoning. An additional search reveals catalysts that rectify this issue as early as 2005.
Work to calculate the energy density comparison when that isn't even the point of the article. Everyone can look up the energey density and theoretical of a li-ion battery: 100-265 Wh/kg. There is absolutely no need to calculate anything.
Focus on the substance of the article. 60x faster charging rate as compared to Lithium-ion and make a comment regarding that. Otherwise your comments are as pointless as my reply to it.