My work gave us an emergency roadside kit that came with jumper cables that had a fold-over crimp like this.
Apparently at least one person used them and ended up with severe burns on their hands. My work instructed everyone to throw the cables away and gave us some coupon as a replacement....
I still have the cables around somewhere.
Just yesterday and today I had to use my jumper cables to help start the van of the people that are installing the new heat pump. Yesterday no problems and the van started after a little bit of charging its battery. Today it did not do anything, so I brought out the trusted multi meter and it showed a lower voltage on the van battery than on mine, so indeed connection problems. Measured the resistance of the cables. The red one was fine <1 Ohm, but the black one had no connectivity until I jiggled one end a bit. Finally got the van going again, and told them to visit a garage to replace the battery. Don't want to jump start it again tomorrow.
The moral of the story, yes the same type of crimping on the big alligator clips, and a bad connection on the copper strand. The clip is steel, but the cable is non magnetic, so either real copper or copper cladded aluminum.
Problem with these clips is that you can't solder to them, at least not easily. I removed the cable from the clip and had to pry the strands out of the insulation. Stripped a larger section and crimped the clip back on. Hopefully it will work again when needed.