Not so says Redflow at
Home - ZCell "
- Intrinsically fire retardant electrolyte - not at risk of thermal runaway
"
Also take a look at 7:34 of this
These have nothing to do with redox flow batteries. Sorry to say, you are not quite understanding the tech there.
In a ZnBr system you precipitate out metallic zinc to 'charge' the system, and you are left with a highly oxidising bromide species that can dissolve metal (clearly, it has to redissolve the zinc for the battery to work in both directions).
Discharge of the battery is redissolving the zinc back to zinc bromide. You can then take that out as 'waste', for sure, but then you have to refit metallic zinc and some bromide-containing complex into the car that can't be pumped by anything as common as a metal because it'll react with it.
I don't really want to be pumping metal-dissolving bromine oxidisers, thanks all the same.
The interview is somewhat disingenuous, IMHO, and also has nothing to do with redox flow batteries, which is usually understood to be two fluids passing either side of a membrane that will selectively pass positive ions. This is simply the situation of a salt flowing over a conductive plate and being electrolysed.
The oxidation of a metal is not an unknown way to generate a primary battery, and you can create an aluminium-air battery that has a huge potential, both literally [electrically] and also as a REx system. You cannot replate aluminium from the hydroxide but you can remove the 'eaten' plates and refresh them physically with new ones. It is just then a case of reducing the aluminium oxide/hydroxides and making new plates to fit. Potentially, that could provide you with your 200kWh mechanically rechargeable (3 minute) system.