Why do you say that? Do SMES have better energy density?
Superconductors have the ability to transfer electrical energy extremely quickly. Which is an ideal characteristic for a battery. I don't know enough about SMESes to say whether they are a good storage solution (assuming we could eventually develop a room temperature one).
They probably don't. Just as there is a critical temperature, Tc, at which superconductors stop superconducting, there is a critical current density, Ic, at which they stop superconducting. That places a limit on the amount of energy you can store in a superconducting loop. Then there is also the consideration that Ic scales as approximately 1/Tc, so high-temperature superconductors have a lower critical current density than low-temperature ones.
Huh, this is weird. Somebody downvoted this comment and my other reply. Care to explain why or are you just going to leave me mystified?
Fine, go ahead whoever you are. I guess I'll just vote everyone's posts down today so maybe I'll catch yours.