Doesn’t seem completely impossible with the estimated storage capacity, but like with all of these things, drastically changing the build up of concrete means changing the properties of the very thing used to hold your home together.
It might be cheap materials, but the effort involved also seem very high having to cut up after the hardening to create the super capacitors. Which again may affect structural integrity.
Also not a researcher, but I also believe hallucinations are simply the artifact of being able generate responses that aren’t pure reproduction of training data. Aka, the generalization we want. The problem is we have something that generalize without the ability to judge what it thinks of.
It will in my opinion never go away, but I’m sure it can be improved significantly.