"Relatively easy != easy."
Tweaking the recipe slightly. Not too expensive. Junk existing chemistry (and probably production machinery). Very expensive.
Why is the concept of a qualified statement so difficult for people to grasp?
*As opposed to say a Hydrofloric Acid and Cream Cheese battery with an operating temperature of 200c, which I'd suggest has f**k all chance of ever moving outside my head (where it was invented 5 seconds ago).
But if I wanted to do something really clever....
I'd look for a fluid I could run through the cooling jackets of heat engines, or the tubes of a boiler, and then run directly into some kind of flow battery. Turning heat directly into electricity, without generators or alternators.
The chemistries a b**ch and the thermodynamic efficiencies seem low (but I'm not sure why).
Making that work would require very high order boffinery indeed.