I don't truly understand this "problem". I understand storing the energy in batteries is currently very expensive economically and materially. However I believe there are plenty of "goods" (irrespective of if they are bulk materials, or partially processed products) which have a high processing energy per volume ratio (this does not need to be recoverable stored energy). Allow me to give an example: currently we have…
I believe aluminum is nicknamed "solid electricity" due to the ore purification process or somesuch; which dovetails well with the strategy you outline here!
Roughly the reason it's not economic is electricity nominally costs about 5 times what coal/nat gas does. And with the current carbon footprint of the grid it probably doesn't reduce CO2 emissions.
But that could change with as clean grid that has wild daily price swings. Electrowinning iron and other metals could easily soak up excess power.