I don't see the point of nanoelectrofuel flow batteries. I'm sure there are niche applications that I can't see. But not anywhere near what that author is describing.
Flow batteries are good because they're so cheap per mAh and W, and if you're using them for grid scale storage, size and weight doesn't matter. The energy density is greatly increased when you add nanoparticles, to the point where it competes with EV batteries. This includes the extra weight of pumps and membranes. I think the addition of pumps and membranes make it really unfit for personal vehicles, even if it increases the energy density. The article talks about military applications, but doesn't really explain what it could do better that Li-ion except for fire safety. And they'd be dependent on the fuel of this one company.
I think its major selling point is that it's cheap and very modular, so you can easily choose what capacity/power your grid scale facility should store/output, and change it after the fact. But if your building a facility, then the weight doesn't matter as much and you might as well skip the nanoparticles.
As a technology I think it's really clever. It's not a very well studied idea. They're tight lipped and I assumed it was some sort of Vanadium flow battery, but judging by the articles they're citing in their patent and their conference talk abstract I'd speculate the cathode nanoelectrofuel is a water based slurry with lithium iron phosphate nanoparticles and carbon powder. The particles discharge like they would in a conventional Li-ion battery. But then instead of charging them you pump the slurry to your big tank, replacing them with charged particles. You need the carbon to conduct the electrons from the suspended particles to the current collector plate.
The electrons can not be stored stationary floating in the vacuum of the bottle. They will immediately attach to the internal surface. The entire bottle is now negatively charged and will accumulate positive charge on the external surface until it is electrically neutral. Now you have a funny looking capacitor with extra steps.
The closest thing in existence are the magnetic bottles used for different fusion reactor designs and particle accelerators. In these, the charged particles are kept moving in a closed loop contained by electromagnets that contiously adjust to keep the system pseudo-stable. These certainly cant store energy.