Holder for 14250 batteries in ICAS smoke detector

This Norwegian ICAS smoke detector shipped with a soldered-in 10-year lithium battery consisting of 3 3.6V primary cells. It's the radioactive type, and will get less sensitive to smoke over time; but they don't seem to make that kind anymore, so now I use it as a supplementary smoke detector alongside an optical one. (Each type has advantages and disadvantages, so it's good to have both.) The battery got weak after 9 years, and I figured maybe I could replace the batteries with lithium ion c