[BariumBlue]

I know we've got cuprates, superconductors formed with copper oxide, useful up to 133Kelvin, higher than Nitrogen cooling's capability of 77K.

I've read of them being used in wind turbines and particle accelerators, as well as concepts for fusion reactors.

Your comment makes it sound like they have insufficient field tolerance / current characteristics though. I don't think I've heard about Cuprates at all recently.

[throwup238]

Cuprates are also brittle ceramics so they’re difficult to shape and larger pieces and assemblies tend to run into issues with grain boundaries that interfere with superconductivity, so there’s a lot of practical issues. The classic superconductors are very low temperature but are much easier to cast.

[FredFS456]

There's a few fusion startup companies using superconducting ReBCO tape to make their magnets. From the results that they're getting, I think we've largely cracked the engineering problems of making "wire" from ReBCO and it's largely just a scaling game now. I do want to point out that they're still cooling with liquid hydrogen at ~20K for high current capacity though.

[cyberax]

I invested in a couple of fusion startups (because why the hell not?), and the word on the street is that flexible tapes/wires are still not a solved question. Nobody can make them with consistent quality in large enough batches.