It's not a new idea, they already exist.
A huge redox-flow battery is currently under construction in Switzerland https://www.swissinfo.ch/eng/climate-solutions/switzerland-b...
A huge redox-flow battery is currently under construction in Switzerland https://www.swissinfo.ch/eng/climate-solutions/switzerland-b...
1.2GWh in a few milliseconds? I'm pressing (X) to doubt.
The 'Just Have a Think' channel did a video on the Swiss battery here - https://www.youtube.com/watch?v=CPAFeTvjVzY