From a technical standpoint, this is an incredible achievement. From a moral or rational one, though, JESUS FUCKING CHRIST THIS IS TERRIBLE.
I just don't even have the energy to list all the ways this is an insane and destabilizing thing to do. Fuck. God, I wish we had any electoral power of America's terrible foreign policy.
That blog post describes how it works in more detail. We now live in a world where any battery could be a bomb, there is no way to detect it and the equipment for making those bomb-batteries costs $15k on Ali Express.
I had a feeling that this war would start something like this. Israel has been a testing ground for advanced military technology/ideas for a while. Now that they are engaging in war it was inevitable that techniques or ideas that they have been hiding would eventually get used leading to the world being more dangerous than it was before.
Also as a side note this is why low tech is such a good idea. A small amount of dependencies usually means something is safer in the long run.
Going low-tech is what got them here. The change to bulkier devices gave Israel the opportunity to insert explosives. Using existing small devices would not have given them that opportunity.
Of course, that would mean Israel could continue spying on their cellular communication. It's a risk calculation.
I mean I dunno, even if you switch to some sort of li-on AAs (something which I think would also be good for other reasons, like making recycling potentially easier, being able to swap batteries between devices, making batteries slightly cheaper), I dunno how many people are gonna want to slice open their own batteries and run tests on what comprises them. Since the half-life on any given set of batteries is probably in the range of multiple years, or at least several months, you'd probably be able to set up an attack before any government agency or private battery replacement or analysis would start getting off the ground to sus out what you're doing.
I think the only reason this might be harder with replaceable batteries, would be that the potential for batteries to get swapped out of devices means that you're less certain to see any kind of explosion from a given device that you've modified, and you're less certain to hit the particular targets that you want, but it doesn't seem like either of those would really be a big problem for whoever would want to do this sort of terrorism in the first place, so I'm not sure that's a major deterrent.