I don't know enough about it but it but I understand it is...

I don't know enough about it but it but I understand it is possible to have a battery that includes multiple types of sub systems and a smart management system that detects the energy required and draws energy from the most appropriate sub system. So for lower level power it would drain the flow battery sub system, for instant high demand it would drain the boost capacitor sub system, and in the middle have an Li subsystem etc...

The management system also manages the charging of sub systems and export to the grid from solar and other energy sources and in include cost of power and efficiency as part of the algorithm that decides what energy is provided from and to the sub systems and between what sub systems.

The issue, as always, is cost and quality/reliability of the overall system.