You're saying that data centers are replacing batteries constantly...just imagine the labor costs on that (and the down time), not even considering the material cost.
I’m the tech doing the battery replacements. The big boy UPSes are typically a 3-5 year replacement cycle. Something like this:
(I just picked the last one on my phone so not a great picture, they’re about the size of a small refrigerator)
On rack mount and desktop style UPSes 18-36 months isn’t unreasonable. Some of the smaller UPSes, like APC 750s, go through batteries even faster. My personal theory is that they just get and stay too hot.
There is typically zero downtime while servicing any of them, every critical system has redundant power supply and battery replacements usually don’t interrupt power output anyway. It would take multiple failures to cause any sort of significant downtime, and if it would, we just do them during scheduled downtime.
Basically, thorium-229 can be excited by conventional lasers instead of gamma rays. Instead of millions of electron volts, it takes less than 10, which means it’s more reliable and more precise.