What is, a Vanadium Redox Flow Battery

Did you hear about the one where we invented a battery that could power a house for years and was charged by the sun? And then quietly gave that technology away. For the same reasons (I’m sure) that we shuttered/destroyed that first mass produced electric car.
Oops! Can’t have that! This would have shut down the gas/oil/coal business, so of course they got rid of it.