Comment by mdasen
It looks like 1-way pagers sold in the US are powered by AA or AAA batteries: https://pagersdirect.net/collections/1-way-pagers.
That's not to say that they couldn't have put a lithium AA or AAA battery into the pagers or inserted a modified AA/AAA battery that was a combination of lithium (with greater power density) and explosive.
It's also possible that they have fancier 1-way pagers than I'm aware of.
According to this post, the pagers that exploded had rechargeable batteries. They even used USB-C, so Hezbollah must be using somewhat fancy pagers: https://x.com/BabakTaghvaee1/status/1836082246538629490