It’s spot welded. Only the ending terminals of the battery are welded with 10 awg flexible copper strand wire. So two major welds. And of course the bms wires. Bms wires are welded to nickel strips.
Those bolts go through the battery like columns like a sandwhich it compresses the covers, kind of like a trampa battery. You can take the battery apart so you can service it easily. e.g. if you need to replace a bad cell you unbolt it and can easily cut the nickel strips, take bad cell out, and place new one, add more nickel strip, revolt it, good to go.
I could take it apart to show you but it’s a lot of work… and forgot to take photos when I was putting it together.