Well, if you can burn it to produce energy + spent fuel
and then put back energy in the spent fuel to make new fuel again
then you have really a battery. That's how li-ion batteries work. The issue is the efficiency: how much of the energy you used to recharge the "battery" (iron) is going to be available when you discharge (burn) it
and then put back energy in the spent fuel to make new fuel again
then you have really a battery. That's how li-ion batteries work. The issue is the efficiency: how much of the energy you used to recharge the "battery" (iron) is going to be available when you discharge (burn) it