While I love the ingenuity of this system, I have some trouble seeing it used as an economically viable energy storage option. According to the article, they would need about 45 m3 to store 10 kwh. At a concrete price of 200-300 $/m3, that would come to 9-13.5k USD just for the concrete. That's omitting any costs for the carbon black electrolyte, material processing, electrolyte separators and other things, so a very optimistic estimate.
Meanwhile, battery prices have fallen so much that you can buy 10 kwh of Li-Ion batteries for about $1500 ($150/kwh 2021 prices). The saving grace might be to have it do double duty as a structural element in the building, but many other posters have pointed out that there are many safety and construction problems that would have to be solved for that first.